Mapper 中的 resultType 使用 pojo 跟使用 java.util.Map 的区别? 5C
<select id="" resultType="pojo类">
        // sql代码 。。。
</select>

<select id="" resultType="java.util.Map">
        // sql代码 。。。
</select>

虽然我知道既然有 pojo 这个概念就不可能纯用 map 去取代它,
但我只知其然不知其所以然,我想知道:
1. 为什么不能纯使用 map?
2. 而在什么情况下,又应该使用 map ?

求大神解答,这个问题困惑我好久了,写着代码都不安心?

6个回答

map的缺点是它缺乏固定的类型,所以从调用者看,没有办法享受开发环境中字段上下文的提示,如果写错了字段名,也没有办法检查出来。map的效率也要比pojo差。
map的好处是免维护一个pojo类,修改数据库字段就行了。编写简单方便。
其实说白了,就是因为java自身的局限,和ruby、python、js甚至C#比,java是静态的语言,缺乏动态类型的支持,所以才需要map这么一个折衷的方案。

就是返回值类型不一样,使用结果都一样。java是面向对象的语言,操作pojo比操作map简单,给你两个返回值,肯定是哪个简单开发用哪个啊。

比如:查询用户列表数据,输出每个用户账号
用pojo你只需要用户列表循环获取账号属性就行;
用map你要循环列表再循环map获取账号属性。

当你觉得sql操作map简单的时候就用map(返回值简单的时候可以用,示例:只查询一个用户的用户名)

resultType通常只有在查询的时候会用到:
使用resultType进行输出映射,只有查询出来的列名和pojo(实体bean)中的属性名一致,该列才可以映射成功。
如果查询出来的列名和pojo的属性名不一致,通过定义一个resultMap对列名和pojo属性名之间作一个映射关系。

qq_28129661
qq_28129661 1、查询的结果集中的字段名称与jopo的属性名称一致时,才会映射成功
大约 2 年之前 回复
qq_28129661
qq_28129661 1、查询的结果集中的字段名称与jopo的属性名称一致时,才会映射成功
大约 2 年之前 回复
qq_31165105
欧阳-95 大佬,我说的是 java.util.Map 。。。。。。。。。。。
大约 2 年之前 回复

道理很简单

假设数据库表table有以下几个列
id title content

你在pojo实体类中有以下几个字段
id title content

这种情况下pojo中的属性名和数据库中的列名一致,这种情况下列里存在的值就可以和实体类相对应,就是可以保证正常映射。
但是:
有的时候一些公司的业务需要为我们的pojo类增加一些前缀,如
csdn_id,csdn_title,csdn_content
这个时候数据库里的列名和实体类不对应,为了让数据库里的值与pojo能正常映射,这个时候就需要为数据库里的列起一个别名,这个时候就用到了resultMap

小结:其实resulttype和resultMap都是mybatis绑定数据库的一种方式,个人更推荐resultmap
另外,通过resultMap也可已配置一对多,多对一的方式,适合多变的需求

qq_37599878
早睡早起身体好才是真的 回答的是牛头不对马嘴
一天之前 回复
sysmwx
倾世烟火为你而唱 回复qq_31165105: 这种情况不常见,一般是创建一个pojo用来接收数据库返回的数据,因为java的三个概念就是那样,如果都用map了那就体现不出封装的重要性,使用map的情况我目前只用过一次,是公司需要一些比较分散的数据,并且只有一个地方调用,如果经常调用,还是建议pojo,因为类比map更好维护
大约 2 年之前 回复
qq_31165105
欧阳-95 大佬,我说的是 java.util.Map 。。。。。。。。。。。
大约 2 年之前 回复

resultType即结果类型 看返回结果来定 各有各的用法

resultType返回值可以自己家设置自己需要的返回对象,而resultMap返回的是xml中定义的返回实体对象,一般返回的实体有扩展字段但resultMap中不包含时就用resutType

Csdn user default icon
上传中...
上传图片
插入图片
抄袭、复制答案,以达到刷声望分或其他目的的行为,在CSDN问答是严格禁止的,一经发现立刻封号。是时候展现真正的技术了!
其他相关推荐
Could not find parameter map java.util.Map 错误

错误: org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.builder.xml.IncompleteStatementException: Could not find parameter map java.util.Map 报错的地方: this.sqlSessionTxTemplate.selectOne("UserManageMapper.addUser", ht); “UserManageMapper.addUser”: <resultMap id="map" type="java.util.HashMap"> </resultMap> <select id="getUserById" parameterType="java.util.Map" resultMap="map"> select * from subscriber where provider_id=#{providerId} order by updated_on desc </select> 之前一直都很正常,现在莫名其妙的报错,而且所有的查询,更新都是报这个错误,检查了很多地方都没发现问题。 请大家帮帮忙

java.util.concurrent.ExecutionException

在eclipse 启动tomcat 报如下错误 java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException

ibatis中动态查询表返回用resultClass="java.util.HashMap" 的问题

用spring+ibatis写了一个登陆页面输入表名 然后在页面查询出表的数据, sql配置文件 </select> <select id="getTableDataByPage" resultClass="java.util.HashMap" parameterClass="java.util.HashMap"> <![CDATA[ select * from (select rownum id,t.* from $tableName$ t where rownum<= #endNum# ) b where b.id>= #startNum# ]]> </select> 第一次运行服务器输入一个表名可以查询出表的所有信息,退出返回到登陆页面重新输入一个表名查询就会出错 日志显示: Cause: java.sql.SQLException: 列名无效 com.ibatis.common.jdbc.exception.NestedSQLException: --- The error occurred in com/zf/querytest/bo/impl/tableDao.xml. --- The error occurred while applying a result map. --- Check the tableDao.getTableDataByPage-AutoResultMap. --- Check the result mapping for the 'TASKID' property. 其中TASKID为上一张表中的字段,也就是ResultMap中保留了上个表的字段信息,将sqlMapClient中的cacheModelsEnabled设置为"false"也不行 请问我要怎样修改才能在重新输入表名后查询后返回新的表的结果了,请大家帮帮忙,谢谢 [b]问题补充:[/b] 感谢lggege的关注,目前只能重新启动才能重新查询另一张表的数据

mybatis——java.util.HashMap cannot be cast to 。。。?

![图片说明](https://img-ask.csdn.net/upload/201911/15/1573808839_31171.png) ![图片说明](https://img-ask.csdn.net/upload/201911/15/1573808853_597304.png) ![图片说明](https://img-ask.csdn.net/upload/201911/15/1573808864_680131.png) 我按照网上的教程写了个mybatis的测试代码 但是在遍历的时候报错了 查了下,好像是类型转换的问题 我改了代码,可以执行,但是一时间想不到有好的遍历的方法。 想请教大神,像这种情况,有没有别的办法可以遍历呢?

Exception in thread "Thread-12" java.lang.RuntimeException: java.lang.NullPointerException

第一次着手项目,springboot+mybatis,项目搭建是跟着教程做的。项目搭建好之后项目能正常运行,但是启动后报: Exception in thread "Thread-12" java.lang.RuntimeException: java.lang.NullPointerException at com.mysql.jdbc.JDBC4Connection$1$1.run(JDBC4Connection.java:106) Caused by: java.lang.NullPointerException at com.mysql.jdbc.ConnectionImpl.abortInternal(ConnectionImpl.java:1240) at com.mysql.jdbc.JDBC4Connection$1$1.run(JDBC4Connection.java:104) 启动Console: 2019-08-05 10:29:12.921 INFO 7416 --- [ restartedMain] com.xintujiuzhang.aimanagement.App : Starting App on DESKTOP-J57CTN6 with PID 7416 (D:\JAVA\eclipse\TaxHandwritingRecognition\target\classes started by Administrator in D:\JAVA\eclipse\TaxHandwritingRecognition) 2019-08-05 10:29:12.921 INFO 7416 --- [ restartedMain] com.xintujiuzhang.aimanagement.App : No active profile set, falling back to default profiles: default 2019-08-05 10:29:12.958 INFO 7416 --- [ restartedMain] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6070b0bb: startup date [Mon Aug 05 10:29:12 CST 2019]; root of context hierarchy 2019-08-05 10:29:13.450 INFO 7416 --- [ restartedMain] o.s.b.f.xml.XmlBeanDefinitionReader : Loading XML bean definitions from class path resource [mybatis-config.xml] 2019-08-05 10:29:13.503 INFO 7416 --- [ restartedMain] o.s.b.f.s.DefaultListableBeanFactory : Overriding bean definition for bean 'sqlSessionFactory' with a different definition: replacing [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=app; factoryMethodName=sqlSessionFactoryBean; initMethodName=null; destroyMethodName=(inferred); defined in com.xintujiuzhang.aimanagement.App] with [Generic bean: class [org.mybatis.spring.SqlSessionFactoryBean]; scope=; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in class path resource [mybatis-config.xml]] 2019-08-05 10:29:13.599 WARN 7416 --- [ restartedMain] o.m.s.mapper.ClassPathMapperScanner : No MyBatis mapper was found in '[com.xintujiuzhang.aimanagement]' package. Please check your configuration. 2019-08-05 10:29:13.958 INFO 7416 --- [ restartedMain] trationDelegate$BeanPostProcessorChecker : Bean 'org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration' of type [org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration$$EnhancerBySpringCGLIB$$b535b905] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 2019-08-05 10:29:14.332 INFO 7416 --- [ restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http) 2019-08-05 10:29:14.348 INFO 7416 --- [ restartedMain] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2019-08-05 10:29:14.349 INFO 7416 --- [ restartedMain] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.28 2019-08-05 10:29:14.355 INFO 7416 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : Loaded APR based Apache Tomcat Native library [1.2.21] using APR version [1.6.5]. 2019-08-05 10:29:14.355 INFO 7416 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : APR capabilities: IPv6 [true], sendfile [true], accept filters [false], random [true]. 2019-08-05 10:29:14.355 INFO 7416 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : APR/OpenSSL configuration: useAprConnector [false], useOpenSSL [true] 2019-08-05 10:29:14.357 INFO 7416 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : OpenSSL successfully initialized [OpenSSL 1.1.1a 20 Nov 2018] 2019-08-05 10:29:14.418 INFO 7416 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2019-08-05 10:29:14.418 INFO 7416 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1462 ms 2019-08-05 10:29:14.514 INFO 7416 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/] 2019-08-05 10:29:14.517 INFO 7416 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*] 2019-08-05 10:29:14.517 INFO 7416 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2019-08-05 10:29:14.517 INFO 7416 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*] 2019-08-05 10:29:14.517 INFO 7416 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*] 2019-08-05 10:29:14.631 INFO 7416 --- [ restartedMain] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Starting... 2019-08-05 10:29:19.625 INFO 7416 --- [ restartedMain] com.zaxxer.hikari.pool.PoolBase : HikariPool-1 - Driver does not support get/set network timeout for connections. (com.mysql.jdbc.JDBC4Connection.getNetworkTimeout()I) 2019-08-05 10:29:19.629 INFO 7416 --- [ restartedMain] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Start completed. 2019-08-05 10:29:19.670 INFO 7416 --- [ restartedMain] j.LocalContainerEntityManagerFactoryBean : Building JPA container EntityManagerFactory for persistence unit 'default' 2019-08-05 10:29:19.684 INFO 7416 --- [ restartedMain] o.hibernate.jpa.internal.util.LogHelper : HHH000204: Processing PersistenceUnitInfo [ name: default ...] 2019-08-05 10:29:19.738 INFO 7416 --- [ restartedMain] org.hibernate.Version : HHH000412: Hibernate Core {5.2.10.Final} 2019-08-05 10:29:19.739 INFO 7416 --- [ restartedMain] org.hibernate.cfg.Environment : HHH000206: hibernate.properties not found 2019-08-05 10:29:19.770 INFO 7416 --- [ restartedMain] o.hibernate.annotations.common.Version : HCANN000001: Hibernate Commons Annotations {5.0.1.Final} 2019-08-05 10:29:19.874 INFO 7416 --- [ restartedMain] org.hibernate.dialect.Dialect : HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect 2019-08-05 10:29:19.897 INFO 7416 --- [ restartedMain] o.h.e.j.e.i.LobCreatorBuilderImpl : HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4 2019-08-05 10:29:20.037 INFO 7416 --- [ restartedMain] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default' 10:29:20,543 INFO App:32-org.springframework.orm.jpa.JpaTransactionManager 2019-08-05 10:29:20.796 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6070b0bb: startup date [Mon Aug 05 10:29:12 CST 2019]; root of context hierarchy 2019-08-05 10:29:20.824 WARN 7416 --- [ restartedMain] aWebConfiguration$JpaWebMvcConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning 2019-08-05 10:29:20.846 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/application/handwriting_authorization],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.ApplicationAuthorizationController.joinHWA(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.847 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/application/handwriting_information],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.ApplicationInformationController.joinHWI(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.847 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/log/background_management_login],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.BackgroundManagementLoginController.joinHWI(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.847 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/log/computer_login],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.ComputerLoginController.jumpDEM(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.847 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/authority/department_management],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.DepartmentManagementController.jumpDEM(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.848 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/authority/dictionary_management],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.DictionaryManagementController.jumpDM(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.848 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/equipment/hardware_devices],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.EquipmentManagementController.jumpDM(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.848 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/queryGetServerStatusInterface],methods=[GET]}" onto public java.util.Map<java.lang.String, java.lang.Object> com.xintujiuzhang.aimanagement.controller.GetServerStatusInterfaceController.queryGetServerStatus(java.lang.String,java.lang.String) 2019-08-05 10:29:20.848 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/queryHandwritingInterface],methods=[GET]}" onto public java.util.Map<java.lang.String, java.lang.Object> com.xintujiuzhang.aimanagement.controller.HandwritingInterfaceController.queryHandwriting(java.lang.String,java.lang.String,java.lang.Integer,java.util.Date) 2019-08-05 10:29:20.849 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/identity/identity_management],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.IdentityManagementController.jumpDM(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.849 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/queryInstallationRequest],methods=[GET]}" onto public java.util.Map<java.lang.String, java.lang.Object> com.xintujiuzhang.aimanagement.controller.InstallationRequestInterfaceController.queryInstallationRequest(java.lang.String,java.lang.String,java.lang.String) 2019-08-05 10:29:20.849 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/queryLicenseInterface],methods=[GET]}" onto public java.util.Map<java.lang.String, java.lang.Object> com.xintujiuzhang.aimanagement.controller.LicenseInterfaceController.queryLicense(java.lang.String,java.lang.String,java.lang.String,java.lang.String,java.lang.String,java.util.Date) 2019-08-05 10:29:20.851 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.MainController.main(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.851 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/login],methods=[GET]}" onto public org.springframework.web.servlet.ModelAndView com.xintujiuzhang.aimanagement.controller.MainController.login() 2019-08-05 10:29:20.851 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/login],methods=[POST]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.MainController.login(java.lang.String,java.lang.String,java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.851 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/main],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.MainController.jumpmain(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.852 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/authority/menu_management],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.MenuManagementController.jumpMM(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.852 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/log/module_browsing],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.ModuleBrowsingController.jumpTM(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.852 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/log/module_operation],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.ModuleOperationController.jumpMM(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.852 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/deletehandwriting],methods=[POST]}" onto public void com.xintujiuzhang.aimanagement.controller.NotesController.deletehandwriting(java.lang.String) 2019-08-05 10:29:20.852 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/updatehandwriting],methods=[POST]}" onto public void com.xintujiuzhang.aimanagement.controller.NotesController.updatehandwriting(com.xintujiuzhang.aimanagement.pojo.Handwriting) 2019-08-05 10:29:20.852 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/addhandwriting],methods=[POST]}" onto public void com.xintujiuzhang.aimanagement.controller.NotesController.addhandwriting(com.xintujiuzhang.aimanagement.pojo.Handwriting) 2019-08-05 10:29:20.853 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/querynotes],methods=[GET]}" onto public com.xintujiuzhang.aimanagement.pojo.Handwriting com.xintujiuzhang.aimanagement.controller.NotesController.querynotes(java.lang.String) 2019-08-05 10:29:20.853 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/authority/parameter_settings],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.parameterSettingsController.jumpPS(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.853 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/authority/role_authorization],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.RoleAuthorizationController.jumpRA(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.853 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/log/service_call],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.ServiceCallController.jumpRA(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.853 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/authority/task_management],methods=[GET]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.TaskManagementController.jumpTM(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.854 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/authority/user_management]}" onto public java.lang.String com.xintujiuzhang.aimanagement.controller.UserController.jnmpUM(java.util.Map<java.lang.String, java.lang.Object>) 2019-08-05 10:29:20.854 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/queryUserInterface],methods=[GET]}" onto public java.util.Map<java.lang.String, java.lang.Object> com.xintujiuzhang.aimanagement.controller.UserInterfaceController.queryLicense(java.lang.String,java.lang.String,java.lang.Integer,java.util.Date) 2019-08-05 10:29:20.854 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/queryVersionCheckingInterface],methods=[GET]}" onto public java.util.Map<java.lang.String, java.lang.Object> com.xintujiuzhang.aimanagement.controller.VersionCheckingInterfaceController.queryVersionChecking(java.lang.String,java.lang.String,java.lang.String,java.lang.String,java.lang.String,java.lang.Integer,java.util.Date) 2019-08-05 10:29:20.854 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/queryVersionupdateInterface],methods=[GET]}" onto public java.util.Map<java.lang.String, java.lang.Object> com.xintujiuzhang.aimanagement.controller.VersionUpdateInterfaceController.queryVersionupdate(java.lang.String,java.lang.String,java.lang.String,java.util.Date) 2019-08-05 10:29:20.857 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest) 2019-08-05 10:29:20.857 INFO 7416 --- [ restartedMain] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse) 2019-08-05 10:29:20.881 INFO 7416 --- [ restartedMain] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2019-08-05 10:29:20.881 INFO 7416 --- [ restartedMain] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2019-08-05 10:29:20.906 INFO 7416 --- [ restartedMain] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2019-08-05 10:29:21.115 INFO 7416 --- [ restartedMain] o.s.b.d.a.OptionalLiveReloadServer : LiveReload server is running on port 35729 2019-08-05 10:29:21.164 INFO 7416 --- [ restartedMain] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup 2019-08-05 10:29:21.165 INFO 7416 --- [ restartedMain] o.s.j.e.a.AnnotationMBeanExporter : Bean with name 'dataSource' has been autodetected for JMX exposure 2019-08-05 10:29:21.170 INFO 7416 --- [ restartedMain] o.s.j.e.a.AnnotationMBeanExporter : Located MBean 'dataSource': registering with JMX server as MBean [com.zaxxer.hikari:name=dataSource,type=HikariDataSource] 2019-08-05 10:29:21.196 INFO 7416 --- [ restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path '' 2019-08-05 10:29:21.198 INFO 7416 --- [ restartedMain] com.xintujiuzhang.aimanagement.App : Started App in 8.458 seconds (JVM running for 8.828) Exception in thread "Thread-12" java.lang.RuntimeException: java.lang.NullPointerException at com.mysql.jdbc.JDBC4Connection$1$1.run(JDBC4Connection.java:106) Caused by: java.lang.NullPointerException at com.mysql.jdbc.ConnectionImpl.abortInternal(ConnectionImpl.java:1240) at com.mysql.jdbc.JDBC4Connection$1$1.run(JDBC4Connection.java:104) **在执行一些方法后“Thread-12”会不断增加** **ps:“Thread-668"**

myBatis中的莫名其妙的java.lang.NullPointerException,求指教

xml: <sql id="querywheresrlnodate"> <!-- ognl访问静态方法的表达式 为@class@method(args),以下为调用Ognl.isNotEmpty()方法,还有其它方法如isNotBlank()可以使用,具体请查看Ognl类 --> <where> <if test="@Ognl@isNotEmpty(h_srlno)"> AND SRLNO = '${h_srlno}' </if> <if test="@Ognl@isNotEmpty(h_date)"> AND URGEDATE = '${h_date}' </if> </where> </sql> <select id="findBySrlnoDate" parameterType="java.util.HashMap" resultType="com.mf.cntrtmng.entity.BsnsOverdueUrge"> SELECT <include refid="selectId" /> FROM bsns_overdue_urge <include refid="querywheresrlnodate"/> </select> DAO: public BsnsOverdueUrge findBySrlnoDate(Map params) throws DataAccessException; Serviceimpl: public boolean exist(Map params) { System.out.println("=====搜索出来的"); System.out.println(params); if(bsnsOverdueUrgeDao.findBySrlnoDate(params)==null) return true; else return false; } 错误日志: =====搜索出来的 {h_srlno=JH201505281535107052, h_date=20150601} 2015-06-01 15:19:42,922 DEBUG [http-bio-8080-exec-3] (JakartaCommonsLoggingImpl.java:46) - Creating a new SqlSession 2015-06-01 15:19:42,922 DEBUG [http-bio-8080-exec-3] (JakartaCommonsLoggingImpl.java:46) - Registering transaction synchronization for SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6d41567b] 2015-06-01 15:19:42,924 DEBUG [http-bio-8080-exec-3] (JakartaCommonsLoggingImpl.java:46) - JDBC Connection [jdbc:mysql://localhost:3306/microfinance?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&autoReconnect=true, UserName=root@localhost, MySQL-AB JDBC Driver] will be managed by Spring 2015-06-01 15:19:42,925 DEBUG [http-bio-8080-exec-3] (JakartaCommonsLoggingImpl.java:46) - ooo Using Connection [jdbc:mysql://localhost:3306/microfinance?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&autoReconnect=true, UserName=root@localhost, MySQL-AB JDBC Driver] 2015-06-01 15:19:42,928 DEBUG [http-bio-8080-exec-3] (JakartaCommonsLoggingImpl.java:46) - ==> Preparing: select count(1) from (SELECT NO, SRLNO, CLNTNO, URGEID, URGENAME, URGEDATE FROM bsns_overdue_urge WHERE SRLNO = 'JH201505281535107052' AND URGEDATE = '20150601') tmp_count 2015-06-01 15:19:42,929 DEBUG [http-bio-8080-exec-3] (JakartaCommonsLoggingImpl.java:46) - ==> Parameters: 2015-06-01 15:19:42,930 DEBUG [http-bio-8080-exec-3] (JakartaCommonsLoggingImpl.java:46) - Releasing transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6d41567b] 2015-06-01 15:19:42,930 DEBUG [http-bio-8080-exec-3] (AbstractPlatformTransactionManager.java:843) - Initiating transaction rollback 2015-06-01 15:19:42,931 DEBUG [http-bio-8080-exec-3] (DataSourceTransactionManager.java:279) - Rolling back JDBC transaction on Connection [jdbc:mysql://localhost:3306/microfinance?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&autoReconnect=true, UserName=root@localhost, MySQL-AB JDBC Driver] 2015-06-01 15:19:42,932 DEBUG [http-bio-8080-exec-3] (JakartaCommonsLoggingImpl.java:46) - Transaction synchronization rolling back SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6d41567b] 2015-06-01 15:19:42,932 DEBUG [http-bio-8080-exec-3] (JakartaCommonsLoggingImpl.java:46) - Transaction synchronization closing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6d41567b] 2015-06-01 15:19:42,933 DEBUG [http-bio-8080-exec-3] (DataSourceTransactionManager.java:322) - Releasing JDBC Connection [jdbc:mysql://localhost:3306/microfinance?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&autoReconnect=true, UserName=root@localhost, MySQL-AB JDBC Driver] after transaction org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: ### Error querying database. Cause: java.lang.NullPointerException ### The error may exist in file [E:\SpringSource\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\microfinance20150203\WEB-INF\classes\com\mf\cntrtmng\entity\mapper\bsnsoverdueurge-mapper.xml] ### The error may involve com.mf.cntrtmng.dao.BsnsOverdueUrgeDao.findBySrlnoDate-Inline ### The error occurred while setting parameters ### Cause: java.lang.NullPointerException 2015-06-01 15:19:42,933 DEBUG [http-bio-8080-exec-3] (DataSourceUtils.java:332) - Returning JDBC Connection to DataSource at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:73) at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:365) at com.sun.proxy.$Proxy11.selectOne(Unknown Source) at org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:160) at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:63) at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:43) at com.sun.proxy.$Proxy114.findBySrlnoDate(Unknown Source) at com.mf.cntrtmng.service.impl.BsnsOverdueUrgeServiceImpl.exist(BsnsOverdueUrgeServiceImpl.java:128) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:319) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202) at com.sun.proxy.$Proxy115.exist(Unknown Source) at com.mf.aftrmng.controller.LoanWarnController.showUrgeInfo(LoanWarnController.java:310) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778) at javax.servlet.http.HttpServlet.service(HttpServlet.java:620) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at com.mf.interceptor.HeadInterceptor.doFilter(HeadInterceptor.java:43) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:315) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) at java.lang.Thread.run(Thread.java:662) 从日志里面打印的SQL,可以在数据库中搜索,怎么返回值变成了count(),我不是在xml中配置的返回值类型为一个对象类型么“resultType="com.mf.cntrtmng.entity.BsnsOverdueUrge"?”然后包了莫名其妙的空指针错误,求大神帮忙看看,小弟感激不尽~~

java.lang.NoClassDefFoundError问题

ssh的修改操作中,我先查询所有数据到页面中显示,然后选中一条进行编辑,根据选中的ID再到数据库中查询该条信息。通过ID查询时报如下错误: lib文件夹中有javassist-3.15.0-GA.jar 提示DAO层报错的代码行:Employee employee = (Employee)getSession().get(Employee.class,id); 严重: Exception occurred during processing request: Method "update1" failed for object com.ja.xly.actions.EmployeeAction@7ed19f51 ognl.MethodFailedException: Method "update1" failed for object com.ja.xly.actions.EmployeeAction@7ed19f51 [java.lang.NoClassDefFoundError: javassist/util/proxy/Proxy] at ognl.OgnlRuntime.callAppropriateMethod(OgnlRuntime.java:1305) at ognl.ObjectMethodAccessor.callMethod(ObjectMethodAccessor.java:68) at com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethodWithDebugInfo(XWorkMethodAccessor.java:117) at com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethod(XWorkMethodAccessor.java:108) at ognl.OgnlRuntime.callMethod(OgnlRuntime.java:1369) at ognl.ASTMethod.getValueBody(ASTMethod.java:90) at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212) at ognl.SimpleNode.getValue(SimpleNode.java:258) at ognl.Ognl.getValue(Ognl.java:494) at ognl.Ognl.getValue(Ognl.java:458) at com.opensymphony.xwork2.ognl.OgnlUtil$2.execute(OgnlUtil.java:309) at com.opensymphony.xwork2.ognl.OgnlUtil.compileAndExecute(OgnlUtil.java:340) at com.opensymphony.xwork2.ognl.OgnlUtil.getValue(OgnlUtil.java:307) at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:423) at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:287) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:250) at org.apache.struts2.interceptor.DeprecationInterceptor.intercept(DeprecationInterceptor.java:41) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265) at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:76) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at org.apache.struts2.interceptor.DateTextFieldInterceptor.intercept(DateTextFieldInterceptor.java:125) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:253) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:139) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54) at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:564) at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81) at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Unknown Source)

java.lang.ClassNotFoundException: org.junit.Test

java.lang.ClassNotFoundException: org.junit.Test at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1856) at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1705) at org.springframework.core.type.classreading.RecursiveAnnotationAttributesVisitor.visitEnd(AnnotationAttributesReadingVisitor.java:167) at org.springframework.asm.ClassReader.a(Unknown Source) at org.springframework.asm.ClassReader.accept(Unknown Source) at org.springframework.asm.ClassReader.accept(Unknown Source) at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:54) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80) at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:101) at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:237) at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.doScan(ClassPathBeanDefinitionScanner.java:242) at org.springframework.context.annotation.ComponentScanBeanDefinitionParser.parse(ComponentScanBeanDefinitionParser.java:84) at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:73) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1419) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1409) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:184) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:140) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:111) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:209) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.importBeanDefinitionResource(DefaultBeanDefinitionDocumentReader.java:239) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseDefaultElement(DefaultBeanDefinitionDocumentReader.java:196) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:181) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:140) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:111) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:209) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:180) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:131) at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:522) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:436) at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:631) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:588) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:645) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:508) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:449) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:133) at javax.servlet.GenericServlet.init(GenericServlet.java:158) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5327) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5617) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652) at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:677) at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1939) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask.run(FutureTask.java:262) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:745)

java报错java.lang.IndexOutOfBoundsException

![图片说明](https://img-ask.csdn.net/upload/201606/04/1465016132_558449.png) ![图片说明](https://img-ask.csdn.net/upload/201606/04/1465016148_409766.png) ![图片说明](https://img-ask.csdn.net/upload/201606/04/1465016141_240819.png) ![图片说明](https://img-ask.csdn.net/upload/201606/04/1465016206_139184.png) Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 at java.util.ArrayList.rangeCheck(ArrayList.java:653) at java.util.ArrayList.get(ArrayList.java:429) at RobotInterface.joke(RobotInterface.java:295) at RobotGUI.main(RobotGUI.java:47) 在mac上跑的时候没有报错,在win上跑的时候就有这样的错误了,然后发现同样的语句在我另一个相似的函数里也有但是没有这样的报错,求谈里大神给分析分析,我baidu的情况来看好像是数组超界了?

SSM 遇到的java.lang.NullPointerException问题

报错 java.lang.NullPointerException ** at com.archives.controller.sysmanage.DepartmentController.doPageData(DepartmentController.java:38) ** at com.archives.controller.sy****smanage.DepartmentController.initHome(DepartmentController.java:32) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:220) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) at javax.servlet.http.HttpServlet.service(HttpServlet.java:624) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:436) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625) at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2517) at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2506) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748) mapper.xml 文件 <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" > <mapper namespace="com.archives.dao.UserDeptDao"> <resultMap id="userdeptMap" type="com.archives.entity.UserDept"> <id column="deptid" property="deptid"></id> <result column="deptname" property="deptname"/> <result column="telephone" property="telephone"/> <result column="fax" property="fax"/> <result column="managerid" property="managerid"/> <result column="remark" property="remark"/> <association property="userInfo" javaType="com.archives.entity.UserInfo"> <id column="loginid" property="loginid"></id> <result column="loginname" property="loginname"/> <result column="loginpwd" property="loginpwd"/> <result column="realname" property="realname"/> <result column="roleid" property="roleid"/> <result column="leveid" property="leveid"/> <result column="cardid" property="cardid"/> <result column="dutyid" property="dutyid"/> <result column="deptid" property="deptid"/> <result column="joindate" property="joindate"/> <result column="telephone" property="telephone"/> <result column="enduid" property="enduid"/> <result column="address" property="address"/> <result column="sex" property="sex"/> </association> </resultMap> <select id="selectUserDeptCount" parameterType="com.archives.model.A0104Model" resultType="Integer"> select count(*) as cnt from userinfo,dept and userinfo.deptid = dept.deptid <if test="loginname != null and loginname.trim() != '' "> and userinfo.loginname = #{loginname} </if> <if test="realname != null and realname.trim() != '' "> and userinfo.realname = #{realname} </if> <if test="deptname != null and deptname.trim() != '' "> and dept.deptname = #{deptname} </if> </select> <select id="selectUserDeptList" parameterType="com.archives.model.A0104Model" resultMap="userdeptMap"> select userinfo.loginid , userinfo.loginname , userinfo.realname , dept.deptname , dept.deptid from userinfo,dept where userinfo.deptid = dept.deptid limit #{offsetindex},#{pageCount} </select> </mapper> controller.java文件 package com.archives.controller.sysmanage; import java.util.List; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import com.alibaba.fastjson.JSON; import com.archives.common.Constant; import com.archives.entity.Menu; import com.archives.entity.UserDept; import com.archives.entity.UserInfo; import com.archives.model.A0104Model; import com.archives.service.HomeService; import com.archives.service.UserDeptService; @Controller @RequestMapping("/department") public class DepartmentController { UserDeptService userdeptService; @RequestMapping("/init") public String initHome(HttpServletRequest request) { A0104Model model=new A0104Model(); model.setCurPage(1); model.setPageCount(Constant.PAGE_COUNT); 对应的错误行**doPageData(request,model);** return "department"; } private void doPageData(HttpServletRequest request, A0104Model model) { // TODO Auto-generated method stub int cnt = userdeptService.selectUserDeptCount(model); int totalPage = 0; if(cnt%Constant.PAGE_COUNT == 0) { totalPage = cnt/Constant.PAGE_COUNT; }else { totalPage = cnt/Constant.PAGE_COUNT + 1; } model.setTotalPage(totalPage); model.setOffsetindex((model.getCurPage() - 1) * Constant.PAGE_COUNT); model.setPageCount(Constant.PAGE_COUNT); 对应的错误行**List<UserDept> userdeptduiyList=userdeptService.selectUserDeptList(model);** request.setAttribute("userdeptList", userdeptList); request.setAttribute("model", model); } } model.java文件 package com.archives.model; public class A0104Model { private String loginname; private String realname; private String deptname; public String getLoginname() { return loginname; } public void setLoginname(String loginname) { this.loginname = loginname; } public String getRealname() { return realname; } public void setRealname(String realname) { this.realname = realname; } public String getDeptname() { return deptname; } public void setDeptname(String deptname) { this.deptname = deptname; } public int getCurPage() { return curPage; } public void setCurPage(int curPage) { this.curPage = curPage; } public int getTotalPage() { return totalPage; } public void setTotalPage(int totalPage) { this.totalPage = totalPage; } public int getOffsetindex() { return offsetindex; } public void setOffsetindex(int offsetindex) { this.offsetindex = offsetindex; } public int getPageCount() { return pageCount; } public void setPageCount(int pageCount) { this.pageCount = pageCount; } private int curPage; private int totalPage; private int offsetindex; private int pageCount; } Dao package com.archives.dao; import java.util.List; import com.archives.entity.UserDept; import com.archives.model.A0104Model; public interface UserDeptDao { UserDeptDao getUserDeptByName(String loginname); int selectUserDeptCount(A0104Model model); List<UserDept> selectUserDeptList(A0104Model model); } service package com.archives.service; import java.util.List; import com.archives.entity.UserDept; import com.archives.model.A0104Model; public interface UserDeptService { int selectUserDeptCount(A0104Model model); List<UserDept> selectUserDeptList(A0104Model model); } serviceImpl package com.archives.service; import java.util.List; import com.archives.dao.UserDeptDao; import com.archives.entity.UserDept; import com.archives.model.A0104Model; public class UserDeptServiceImpl implements UserDeptService { UserDeptDao userdeptDao; @Override public int selectUserDeptCount(A0104Model model) { // TODO Auto-generated method stub int cnt=userdeptDao.selectUserDeptCount(model); return cnt; } @Override public List<UserDept> selectUserDeptList(A0104Model model) { // TODO Auto-generated method stub List<UserDept> userdeptList =userdeptDao.selectUserDeptList(model); return userdeptList; } } UserDept.java package com.archives.entity; public class UserDept { private int deptid; private String deptname; private String telephone; private String fax; private String managerid; private String remark; public String getTelephone() { return telephone; } public void setTelephone(String telephone) { this.telephone = telephone; } public String getFax() { return fax; } public void setFax(String fax) { this.fax = fax; } public String getManagerid() { return managerid; } public void setManagerid(String managerid) { this.managerid = managerid; } public String getRemark() { return remark; } public void setRemark(String remark) { this.remark = remark; } public int getDeptid() { return deptid; } public void setDeptid(int deptid) { this.deptid = deptid; } public String getDeptname() { return deptname; } public void setDeptname(String deptname) { this.deptname = deptname; } public String getLoginid() { return loginid; } public void setLoginid(String loginid) { this.loginid = loginid; } public String getLoginname() { return loginname; } public void setLoginname(String loginname) { this.loginname = loginname; } public String getRealname() { return realname; } public void setRealname(String realname) { this.realname = realname; } private String loginid; private String loginname; private String realname; }

java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat].StandardHost[localhost].TomcatEmbeddedContext[]]

idea中springboot内置tomcat起不起来 pom.xml: <?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.2.1.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.aipuer</groupId> <artifactId>spring-boot</artifactId> <version>0.0.1-SNAPSHOT</version> <name>spring-boot</name> <description>Demo project for Spring Boot</description> <properties> <java.version>11</java.version> </properties> <dependencies> <!-- springBoot 的启动器 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!-- springBoot 的启动器 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> <!-- Mybatis 启动器 --> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.1.1</version> </dependency> <!-- mysql 数据库驱动 --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <!-- druid 数据库连接池 --> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.0.9</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <version>1.5.9.RELEASE</version> </plugin> </plugins> </build> </project> 错误代码: 2019-12-03 10:08:21.181 INFO 7936 --- [ main] com.aipuer.springboot.Application : Starting Application on PC-20191121IKBV with PID 7936 (E:\java\develop\javacode\spring-boot\target\classes started by Administrator in E:\java\develop\javacode\spring-boot) 2019-12-03 10:08:21.183 INFO 7936 --- [ main] com.aipuer.springboot.Application : No active profile set, falling back to default profiles: default 2019-12-03 10:08:21.554 WARN 7936 --- [ main] o.m.s.mapper.ClassPathMapperScanner : No MyBatis mapper was found in '[com.aipuer.springboot]' package. Please check your configuration. 2019-12-03 10:08:21.839 INFO 7936 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http) 2019-12-03 10:08:21.844 INFO 7936 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2019-12-03 10:08:21.844 INFO 7936 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.27] 2019-12-03 10:08:21.888 ERROR 7936 --- [ main] org.apache.catalina.core.ContainerBase : A child container failed during start java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [NonLoginAuthenticator[StandardEngine[Tomcat].StandardHost[localhost].TomcatEmbeddedContext[]]] at java.base/java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[na:na] at java.base/java.util.concurrent.FutureTask.get(FutureTask.java:191) ~[na:na] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:916) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[na:na] at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:140) ~[na:na] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.startup.Tomcat.start(Tomcat.java:459) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:107) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.<init>(TomcatWebServer.java:88) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:438) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:191) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:180) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:153) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:544) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at com.aipuer.springboot.Application.main(Application.java:10) ~[classes/:na] Caused by: org.apache.catalina.LifecycleException: Failed to start component [NonLoginAuthenticator[StandardEngine[Tomcat].StandardHost[localhost].TomcatEmbeddedContext[]]] at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardPipeline.startInternal(StandardPipeline.java:176) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5063) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[na:na] at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:140) ~[na:na] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909) ~[tomcat-embed-core-9.0.27.jar:9.0.27] ... 29 common frames omitted Caused by: java.lang.NoSuchMethodError: 'java.lang.String javax.servlet.ServletContext.getVirtualServerName()' at org.apache.catalina.authenticator.AuthenticatorBase.startInternal(AuthenticatorBase.java:1220) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] ... 39 common frames omitted 2019-12-03 10:08:21.889 ERROR 7936 --- [ main] org.apache.catalina.core.ContainerBase : A child container failed during start java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: A child container failed during start at java.base/java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[na:na] at java.base/java.util.concurrent.FutureTask.get(FutureTask.java:191) ~[na:na] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:916) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.startup.Tomcat.start(Tomcat.java:459) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:107) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.<init>(TomcatWebServer.java:88) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:438) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:191) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:180) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:153) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:544) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) ~[spring-boot-2.2.1.RELEASE.jar:2.2.1.RELEASE] at com.aipuer.springboot.Application.main(Application.java:10) ~[classes/:na] Caused by: org.apache.catalina.LifecycleException: A child container failed during start at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:928) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:841) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[na:na] at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:140) ~[na:na] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909) ~[tomcat-embed-core-9.0.27.jar:9.0.27] ... 21 common frames omitted Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [NonLoginAuthenticator[StandardEngine[Tomcat].StandardHost[localhost].TomcatEmbeddedContext[]]] at java.base/java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[na:na] at java.base/java.util.concurrent.FutureTask.get(FutureTask.java:191) ~[na:na] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:916) ~[tomcat-embed-core-9.0.27.jar:9.0.27] ... 29 common frames omitted Caused by: org.apache.catalina.LifecycleException: Failed to start component [NonLoginAuthenticator[StandardEngine[Tomcat].StandardHost[localhost].TomcatEmbeddedContext[]]] at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardPipeline.startInternal(StandardPipeline.java:176) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5063) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1384) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1374) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) ~[na:na] at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:140) ~[na:na] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:909) ~[tomcat-embed-core-9.0.27.jar:9.0.27] ... 29 common frames omitted Caused by: java.lang.NoSuchMethodError: 'java.lang.String javax.servlet.ServletContext.getVirtualServerName()' at org.apache.catalina.authenticator.AuthenticatorBase.startInternal(AuthenticatorBase.java:1220) ~[tomcat-embed-core-9.0.27.jar:9.0.27] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183) ~[tomcat-embed-core-9.0.27.jar:9.0.27] ... 39 common frames omitted 2019-12-03 10:08:21.889 INFO 7936 --- [ main] o.apache.catalina.core.StandardService : Stopping service [Tomcat] 2019-12-03 10:08:21.900 WARN 7936 --- [ main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat 2019-12-03 10:08:21.906 INFO 7936 --- [ main] ConditionEvaluationReportLoggingListener : Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled. 2019-12-03 10:08:21.909 ERROR 7936 --- [ main] o.s.b.d.LoggingFailureAnalysisReporter : *************************** APPLICATION FAILED TO START *************************** Description: An attempt was made to call a method that does not exist. The attempt was made from the following location: org.apache.catalina.authenticator.AuthenticatorBase.startInternal(AuthenticatorBase.java:1220) The following method did not exist: 'java.lang.String javax.servlet.ServletContext.getVirtualServerName()' The method's class, javax.servlet.ServletContext, is available from the following locations: jar:file:/E:/java/develop/javacode/spring-boot/lib/javaee.jar!/javax/servlet/ServletContext.class jar:file:/E:/maven/maven_repository/org/apache/tomcat/embed/tomcat-embed-core/9.0.27/tomcat-embed-core-9.0.27.jar!/javax/servlet/ServletContext.class It was loaded from the following location: file:/E:/java/develop/javacode/spring-boot/lib/javaee.jar Action: Correct the classpath of your application so that it contains a single, compatible version of javax.servlet.ServletContext Disconnected from the target VM, address: '127.0.0.1:52758', transport: 'socket' Process finished with exit code 1

运行hive出现的错误Exception in thread "main" java.lang.ClassNotFoundException: org.apache.hive.beeline.HiveSchemaTool

``` [root@bigdata113 bin]# ./schematool -dbType mysql -initSchema Exception in thread "main" java.lang.ClassNotFoundException: org.apache.hive.beeline.HiveSchemaTool at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:348) at org.apache.hadoop.util.RunJar.run(RunJar.java:214) at org.apache.hadoop.util.RunJar.main(RunJar.java:136) ``` 求怎么jie'ju

java.lang.NoSuchMethodError异常

严重: Servlet.service() for servlet [springMVC] in context with path [/gameManage] threw exception [Filter execution threw an exception] with root cause java.lang.NoSuchMethodError: org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.isAsyncDispatch(Ljavax/servlet/http/HttpServletRequest;)Z at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:208) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:61) at org.apache.shiro.web.servlet.AdviceFilter.executeChain(AdviceFilter.java:108) at org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:137) at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125) at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:66) at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449) at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365) at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90) at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83) at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:380) at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362) at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:395) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:250) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) 请问一下这个异常是什么原因导致的呢?

在用ssm做项目是碰到java.lang.NullPointerException请问怎么解决

严重: Servlet.service() for servlet [springMVC] in context with path [/goods2] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause java.lang.NullPointerException at com.echeng.service.imp.GoodsServiceImp.getlist(GoodsServiceImp.java:17) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:302) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99) at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208) at com.sun.proxy.$Proxy15.getlist(Unknown Source) at com.echeng.controller.GoodsController.getlist(GoodsController.java:19) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:222) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:814) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:737) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:969) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:860) at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:845) at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:745) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)

java web java.lang.NullPointerException

严重: Servlet.service() for servlet [selectServlet] in context with path [/Exercise] threw exception java.lang.NullPointerException at DB.DataBaseConnection.selectOperation1(DataBaseConnection.java:45) at Servlet.Select.doPost(Select.java:69) at javax.servlet.http.HttpServlet.service(HttpServlet.java:646) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1074) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:619) 代码: public class DataBaseConnection { static String driverString="com.mysql.jdbc.Driver"; static String urlString="jdbc:mysql://localhost:3306/book"; static String username="root"; static String password="123"; public static Connection getConnection() { Connection connection; try { Class.forName(driverString); } catch (ClassNotFoundException e) { e.printStackTrace(); return null; // TODO: handle exception } try { connection=DriverManager.getConnection(urlString, username, password); } catch (SQLException e) { e.printStackTrace(); return null; // TODO: handle exception } return connection; } public static ResultSet selectOperation1(String Content,String SelectWay) { Connection connection=getConnection(); Statement statement=null; try { statement=connection.createStatement();//这一行报错。。 String sqlString="select * from bookinfo where 1=1"; if(Content!=""&&SelectWay!="") { sqlString+="and"+SelectWay+"='"+Content+"'"; } ResultSet rs=statement.executeQuery(sqlString); return rs; } catch (SQLException e) { e.printStackTrace(); return null; // TODO: handle exception } }

Error parsing SQL Mapper Configuration. Cause: java.io.IOException:

mybatis启动一直报错Error parsing SQL Mapper Configuration. Cause: java.io.IOException: 找不到映射。![图片说明](https://img-ask.csdn.net/upload/202006/22/1592829139_577961.jpg) 结构 然后pom.xml 文件中也写了![图片说明](https://img-ask.csdn.net/upload/202006/22/1592829276_55338.png)![图片说明](https://img-ask.csdn.net/upload/202006/22/1592829280_303075.png)

Exception in thread "main" java.lang.NoClassDefFoundError,有导入对应jar包,但显示无法找到对应类?

**spring项目,main函数中调用ApplicationContext类** ``` import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml"); TextEditor te = (TextEditor) context.getBean("textEditor"); te.spellCheck(); } } ``` **也有导入相应jar包** ![图片说明](https://img-ask.csdn.net/upload/201902/12/1549956155_70845.png) **但是运行后会提示** ![图片说明](https://img-ask.csdn.net/upload/201902/12/1549956248_826403.png) **且报错如下** ``` Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/context/ApplicationContext at java.lang.Class.getDeclaredMethods0(Native Method) at java.lang.Class.privateGetDeclaredMethods(Class.java:2701) at java.lang.Class.privateGetMethodRecursive(Class.java:3048) at java.lang.Class.getMethod0(Class.java:3018) at java.lang.Class.getMethod(Class.java:1784) at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:544) at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:526) Caused by: java.lang.ClassNotFoundException: org.springframework.context.ApplicationContext at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ... 7 more ``` **请问应如何解决呢?**

java.lang.NumberFormatException: For input string

直接在浏览器访问tolist.do,这是一个列出数据库帖子的请求,测试可以查询获取到pList中,但是执行controller中的model.addAttribute("pList", pList);这句就会报错,注释掉就没有报错。 求大神解答,万分感谢!!! 报错信息: ![图片说明](https://img-ask.csdn.net/upload/201707/17/1500298791_20553.png) 还有debug信息: ``` DEBUG [http-bio-8080-exec-3] - Rendering view [org.springframework.web.servlet.view.InternalResourceView: unnamed; URL [index.jsp]] in DispatcherServlet with name 'springmvc' DEBUG [http-bio-8080-exec-3] - Added model object 'pList' of type [java.util.ArrayList] to request in view with name 'null' DEBUG [http-bio-8080-exec-3] - Forwarding to resource [index.jsp] in InternalResourceView 'null' 七月 17, 2017 9:36:36 下午 org.apache.catalina.core.ApplicationDispatcher invoke 严重: Servlet.service() for servlet jsp threw exception java.lang.NumberFormatException: For input string: "title" at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) at java.lang.Integer.parseInt(Integer.java:580) ``` mapper.xml ``` <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="cn.edu.mapper.PostMapper"> <resultMap type="post" id="postResult"> <id property="id" column="pid"></id> </resultMap> <insert id="insert" parameterType="post" useGeneratedKeys="true" keyProperty="id"> insert into t_post values(null,#{title},#{author},#{content},now()) </insert> <select id="findAll" resultMap="postResult"> select * from t_post </select> <select id="findById" parameterType="Integer" resultMap="postResult"> select * from t_post where pid = #{id} </select> <select id="findByTitle" parameterType="String" resultMap="postResult"> select * from t_post where title = #{title} </select> </mapper> ``` service ``` package cn.edu.service; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import cn.edu.mapper.CommentMapper; import cn.edu.mapper.PostMapper; import cn.edu.pojo.Comment; import cn.edu.pojo.Post; import cn.edu.pojo.PostComment; @Service public class PostServiceImpl implements PostService { @Autowired private PostMapper postMapperImpl; @Override public String insert(Post post) { Integer id = postMapperImpl.insert(post); String msg = "1"; System.out.println(id); if(id == null){ msg = "0"; } return msg; } @Override public List<Post> findAllPosts() { return postMapperImpl.findAll(); } } ``` controller ``` package cn.edu.controller; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import cn.edu.pojo.Comment; import cn.edu.pojo.Post; import cn.edu.service.PostService; @Controller public class PostController { @Autowired private PostService postServiceImpl; @RequestMapping("tolist") public String toList(Model model){ List<Post> pList = postServiceImpl.findAllPosts(); model.addAttribute("pList", pList); return "forward:index.jsp"; } } ```

Cause: java.lang.NoSuchMethodException: spring_cache.springtest.dao.Employee.<init>()?

![图片说明](https://img-ask.csdn.net/upload/201810/06/1538800958_237033.jpg) 以下是pojo ``` package spring_cache.springtest.pojo; public class Employee { private Integer id; private String lastName; private String email; //性别 1男 0女 private Integer gender; private Integer dId; public Employee() { } public Employee(Integer id, String lastName, String email, Integer gender, Integer dId) { super(); this.id = id; this.lastName = lastName; this.email = email; this.gender = gender; this.dId = dId; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public Integer getGender() { return gender; } public void setGender(Integer gender) { this.gender = gender; } public Integer getdId() { return dId; } public void setdId(Integer dId) { this.dId = dId; } @Override public String toString() { return "Employee [id=" + id + ", lastName=" + lastName + ", email=" + email + ", gender=" + gender + ", dId=" + dId + "]"; } } ``` mapper文件 ``` package spring_cache.springtest.dao; import org.apache.ibatis.annotations.*; /** * @author Dell */ @Mapper public interface Employee { @Select("SELECT * FROM employee WHERE id=#{id}") public Employee getEmployeeById(Integer id); @Update("update Employee set lastName=#{lastName},email=#{email},gender=#{gender},d_id=#{dId} where id=#{id}") public Employee updateEmp(Employee emp); @Delete("delete from Employee where id=#{id}") public void deleteEmp(Employee emp); @Insert("insert into Employee(lastName,email,gender,d_id) values(#{lastName},#{email},#{gender},#{dId})") public void InsertEmp(Employee emp); } ``` 配置文件 ``` spring.datasource.url=jdbc:mysql://localhost:3306/spring_cache spring.datasource.username=root spring.datasource.password=123 ``` 测试类 ``` package spring_cache.springtest; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.test.context.junit4.SpringRunner; import spring_cache.springtest.dao.Employee; @RunWith(SpringRunner.class) @SpringBootTest public class SpringtestApplicationTests { @Autowired Employee employee; @Test public void contextLoads() { Employee employeeById = employee.getEmployeeById(1); System.out.println(employeeById); } } ``` 错误信息 ``` Caused by: org.apache.ibatis.reflection.ReflectionException: Error instantiating interface spring_cache.springtest.dao.Employee with invalid types () or values (). Cause: java.lang.NoSuchMethodException: spring_cache.springtest.dao.Employee.<init>() ```

MySQL 8.0.19安装教程(windows 64位)

话不多说直接开干 目录 1-先去官网下载点击的MySQL的下载​ 2-配置初始化的my.ini文件的文件 3-初始化MySQL 4-安装MySQL服务 + 启动MySQL 服务 5-连接MySQL + 修改密码 先去官网下载点击的MySQL的下载 下载完成后解压 解压完是这个样子 配置初始化的my.ini文件的文件 ...

Python+OpenCV计算机视觉

Python+OpenCV计算机视觉系统全面的介绍。

Vue.js 2.0之全家桶系列视频课程

基于新的Vue.js 2.3版本, 目前新全的Vue.js教学视频,让你少走弯路,直达技术前沿! 1. 包含Vue.js全家桶(vue.js、vue-router、axios、vuex、vue-cli、webpack、ElementUI等) 2. 采用笔记+代码案例的形式讲解,通俗易懂

navicat(内含激活码)

navicat支持mysql的可视化操作,内涵激活码,不用再忍受弹框的痛苦。

HTML期末大作业

这是我自己做的HTML期末大作业,花了很多时间,稍加修改就可以作为自己的作业了,而且也可以作为学习参考

150讲轻松搞定Python网络爬虫

【为什么学爬虫?】 &nbsp; &nbsp; &nbsp; &nbsp;1、爬虫入手容易,但是深入较难,如何写出高效率的爬虫,如何写出灵活性高可扩展的爬虫都是一项技术活。另外在爬虫过程中,经常容易遇到被反爬虫,比如字体反爬、IP识别、验证码等,如何层层攻克难点拿到想要的数据,这门课程,你都能学到! &nbsp; &nbsp; &nbsp; &nbsp;2、如果是作为一个其他行业的开发者,比如app开发,web开发,学习爬虫能让你加强对技术的认知,能够开发出更加安全的软件和网站 【课程设计】 一个完整的爬虫程序,无论大小,总体来说可以分成三个步骤,分别是: 网络请求:模拟浏览器的行为从网上抓取数据。 数据解析:将请求下来的数据进行过滤,提取我们想要的数据。 数据存储:将提取到的数据存储到硬盘或者内存中。比如用mysql数据库或者redis等。 那么本课程也是按照这几个步骤循序渐进的进行讲解,带领学生完整的掌握每个步骤的技术。另外,因为爬虫的多样性,在爬取的过程中可能会发生被反爬、效率低下等。因此我们又增加了两个章节用来提高爬虫程序的灵活性,分别是: 爬虫进阶:包括IP代理,多线程爬虫,图形验证码识别、JS加密解密、动态网页爬虫、字体反爬识别等。 Scrapy和分布式爬虫:Scrapy框架、Scrapy-redis组件、分布式爬虫等。 通过爬虫进阶的知识点我们能应付大量的反爬网站,而Scrapy框架作为一个专业的爬虫框架,使用他可以快速提高我们编写爬虫程序的效率和速度。另外如果一台机器不能满足你的需求,我们可以用分布式爬虫让多台机器帮助你快速爬取数据。 &nbsp; 从基础爬虫到商业化应用爬虫,本套课程满足您的所有需求! 【课程服务】 专属付费社群+每周三讨论会+1v1答疑

三个项目玩转深度学习(附1G源码)

从事大数据与人工智能开发与实践约十年,钱老师亲自见证了大数据行业的发展与人工智能的从冷到热。事实证明,计算机技术的发展,算力突破,海量数据,机器人技术等,开启了第四次工业革命的序章。深度学习图像分类一直是人工智能的经典任务,是智慧零售、安防、无人驾驶等机器视觉应用领域的核心技术之一,掌握图像分类技术是机器视觉学习的重中之重。针对现有线上学习的特点与实际需求,我们开发了人工智能案例实战系列课程。打造:以项目案例实践为驱动的课程学习方式,覆盖了智能零售,智慧交通等常见领域,通过基础学习、项目案例实践、社群答疑,三维立体的方式,打造最好的学习效果。

基于STM32的电子时钟设计

时钟功能 还有闹钟功能,温湿度功能,整点报时功能 你值得拥有

学生成绩管理系统(PHP + MYSQL)

做的是数据库课程设计,使用的php + MySQL,本来是黄金搭配也就没啥说的,推荐使用wamp服务器,里面有详细的使用说明,带有界面的啊!呵呵 不行的话,可以给我留言!

面试了一个 31 岁程序员,让我有所触动,30岁以上的程序员该何去何从?

最近面试了一个31岁8年经验的程序猿,让我有点感慨,大龄程序猿该何去何从。

程序员的兼职技能课

获取讲师答疑方式: 在付费视频第一节(触摸命令_ALL)片头有二维码及加群流程介绍 限时福利 原价99元,今日仅需39元!购课添加小助手(微信号:itxy41)按提示还可领取价值800元的编程大礼包! 讲师介绍: 苏奕嘉&nbsp;前阿里UC项目工程师 脚本开发平台官方认证满级(六级)开发者。 我将如何教会你通过【定制脚本】赚到你人生的第一桶金? 零基础程序定制脚本开发课程,是完全针对零脚本开发经验的小白而设计,课程内容共分为3大阶段: ①前期将带你掌握Q开发语言和界面交互开发能力; ②中期通过实战来制作有具体需求的定制脚本; ③后期将解锁脚本的更高阶玩法,打通任督二脉; ④应用定制脚本合法赚取额外收入的完整经验分享,带你通过程序定制脚本开发这项副业,赚取到你的第一桶金!

实用主义学Python(小白也容易上手的Python实用案例)

原价169,限时立减100元! 系统掌握Python核心语法16点,轻松应对工作中80%以上的Python使用场景! 69元=72讲+源码+社群答疑+讲师社群分享会&nbsp; 【哪些人适合学习这门课程?】 1)大学生,平时只学习了Python理论,并未接触Python实战问题; 2)对Python实用技能掌握薄弱的人,自动化、爬虫、数据分析能让你快速提高工作效率; 3)想学习新技术,如:人工智能、机器学习、深度学习等,这门课程是你的必修课程; 4)想修炼更好的编程内功,优秀的工程师肯定不能只会一门语言,Python语言功能强大、使用高效、简单易学。 【超实用技能】 从零开始 自动生成工作周报 职场升级 豆瓣电影数据爬取 实用案例 奥运冠军数据分析 自动化办公:通过Python自动化分析Excel数据并自动操作Word文档,最终获得一份基于Excel表格的数据分析报告。 豆瓣电影爬虫:通过Python自动爬取豆瓣电影信息并将电影图片保存到本地。 奥运会数据分析实战 简介:通过Python分析120年间奥运会的数据,从不同角度入手分析,从而得出一些有趣的结论。 【超人气老师】 二两 中国人工智能协会高级会员 生成对抗神经网络研究者 《深入浅出生成对抗网络:原理剖析与TensorFlow实现》一书作者 阿里云大学云学院导师 前大型游戏公司后端工程师 【超丰富实用案例】 0)图片背景去除案例 1)自动生成工作周报案例 2)豆瓣电影数据爬取案例 3)奥运会数据分析案例 4)自动处理邮件案例 5)github信息爬取/更新提醒案例 6)B站百大UP信息爬取与分析案例 7)构建自己的论文网站案例

Java8零基础入门视频教程

这门课程基于主流的java8平台,由浅入深的详细讲解了java SE的开发技术,可以使java方向的入门学员,快速扎实的掌握java开发技术!

Python数据挖掘简易入门

&nbsp; &nbsp; &nbsp; &nbsp; 本课程为Python数据挖掘方向的入门课程,课程主要以真实数据为基础,详细介绍数据挖掘入门的流程和使用Python实现pandas与numpy在数据挖掘方向的运用,并深入学习如何运用scikit-learn调用常用的数据挖掘算法解决数据挖掘问题,为进一步深入学习数据挖掘打下扎实的基础。

零基础学C#编程—C#从小白到大咖

本课程从初学者角度出发,提供了C#从入门到成为程序开发高手所需要掌握的各方面知识和技术。 【课程特点】 1 由浅入深,编排合理; 2 视频讲解,精彩详尽; 3 丰富实例,轻松易学; 4 每章总结配有难点解析文档。 15大章节,228课时,1756分钟与你一同进步!

MySQL数据库面试题(2020最新版)

文章目录数据库基础知识为什么要使用数据库什么是SQL?什么是MySQL?数据库三大范式是什么mysql有关权限的表都有哪几个MySQL的binlog有有几种录入格式?分别有什么区别?数据类型mysql有哪些数据类型引擎MySQL存储引擎MyISAM与InnoDB区别MyISAM索引与InnoDB索引的区别?InnoDB引擎的4大特性存储引擎选择索引什么是索引?索引有哪些优缺点?索引使用场景(重点)...

多功能数字钟.zip

利用数字电子计数知识设计并制作的数字电子钟(含multisim仿真),该数字钟具有显示星期、24小时制时间、闹铃、整点报时、时间校准功能

极简JAVA学习营第四期(报名以后加助教微信:eduxy-1)

想学好JAVA必须要报两万的培训班吗? Java大神勿入 如果你: 零基础想学JAVA却不知道从何入手 看了一堆书和视频却还是连JAVA的环境都搭建不起来 囊中羞涩面对两万起的JAVA培训班不忍直视 在职没有每天大块的时间专门学习JAVA 那么恭喜你找到组织了,在这里有: 1. 一群志同道合立志学好JAVA的同学一起学习讨论JAVA 2. 灵活机动的学习时间完成特定学习任务+每日编程实战练习 3. 热心助人的助教和讲师及时帮你解决问题,不按时完成作业小心助教老师的家访哦 上一张图看看前辈的感悟: &nbsp; &nbsp; 大家一定迫不及待想知道什么是极简JAVA学习营了吧,下面就来给大家说道说道: 什么是极简JAVA学习营? 1. 针对Java小白或者初级Java学习者; 2. 利用9天时间,每天1个小时时间; 3.通过 每日作业 / 组队PK / 助教答疑 / 实战编程 / 项目答辩 / 社群讨论 / 趣味知识抢答等方式让学员爱上学习编程 , 最终实现能独立开发一个基于控制台的‘库存管理系统’ 的学习模式 极简JAVA学习营是怎么学习的? &nbsp; 如何报名? 只要购买了极简JAVA一:JAVA入门就算报名成功! &nbsp;本期为第四期极简JAVA学习营,我们来看看往期学员的学习状态: 作业看这里~ &nbsp; 助教的作业报告是不是很专业 不交作业打屁屁 助教答疑是不是很用心 &nbsp; 有奖抢答大家玩的很嗨啊 &nbsp; &nbsp; 项目答辩终于开始啦 &nbsp; 优秀者的获奖感言 &nbsp; 这是答辩项目的效果 &nbsp; &nbsp; 这么细致的服务,这么好的氛围,这样的学习效果,需要多少钱呢? 不要1999,不要199,不要99,只要9.9 是的你没听错,只要9.9以上所有就都属于你了 如果你: 1、&nbsp;想学JAVA没有基础 2、&nbsp;想学JAVA没有整块的时间 3、&nbsp;想学JAVA没有足够的预算 还等什么?赶紧报名吧,抓紧抢位,本期只招300人,错过只有等时间待定的下一期了 &nbsp; 报名请加小助手微信:eduxy-1 &nbsp; &nbsp;

Python可以这样学(第一季:Python内功修炼)

董付国系列教材《Python程序设计基础》、《Python程序设计(第2版)》、《Python可以这样学》配套视频,讲解Python 3.5.x和3.6.x语法、内置对象用法、选择与循环以及函数设计与使用、lambda表达式用法、字符串与正则表达式应用、面向对象编程、文本文件与二进制文件操作、目录操作与系统运维、异常处理结构。

Java基础知识面试题(2020最新版)

文章目录Java概述何为编程什么是Javajdk1.5之后的三大版本JVM、JRE和JDK的关系什么是跨平台性?原理是什么Java语言有哪些特点什么是字节码?采用字节码的最大好处是什么什么是Java程序的主类?应用程序和小程序的主类有何不同?Java应用程序与小程序之间有那些差别?Java和C++的区别Oracle JDK 和 OpenJDK 的对比基础语法数据类型Java有哪些数据类型switc...

机器学习实战系列套餐(必备基础+经典算法+案例实战)

机器学习实战系列套餐以实战为出发点,帮助同学们快速掌握机器学习领域必备经典算法原理并结合Python工具包进行实战应用。建议学习顺序:1.Python必备工具包:掌握实战工具 2.机器学习算法与实战应用:数学原理与应用方法都是必备技能 3.数据挖掘实战:通过真实数据集进行项目实战。按照下列课程顺序学习即可! 课程风格通俗易懂,用最接地气的方式带领大家轻松进军机器学习!提供所有课程代码,PPT与实战数据,有任何问题欢迎随时与我讨论。

Java面试题大全(2020版)

发现网上很多Java面试题都没有答案,所以花了很长时间搜集整理出来了这套Java面试题大全,希望对大家有帮助哈~ 本套Java面试题大全,全的不能再全,哈哈~ 一、Java 基础 1. JDK 和 JRE 有什么区别? JDK:Java Development Kit 的简称,java 开发工具包,提供了 java 的开发环境和运行环境。 JRE:Java Runtime Environ...

程序员垃圾简历长什么样?

已经连续五年参加大厂校招、社招的技术面试工作,简历看的不下于万份 这篇文章会用实例告诉你,什么是差的程序员简历! 疫情快要结束了,各个公司也都开始春招了,作为即将红遍大江南北的新晋UP主,那当然要为小伙伴们做点事(手动狗头)。 就在公众号里公开征简历,义务帮大家看,并一一点评。《启舰:春招在即,义务帮大家看看简历吧》 一石激起千层浪,三天收到两百多封简历。 花光了两个星期的所有空闲时...

深度学习原理+项目实战+算法详解+主流框架(套餐)

深度学习系列课程从深度学习基础知识点开始讲解一步步进入神经网络的世界再到卷积和递归神经网络,详解各大经典网络架构。实战部分选择当下最火爆深度学习框架PyTorch与Tensorflow/Keras,全程实战演示框架核心使用与建模方法。项目实战部分选择计算机视觉与自然语言处理领域经典项目,从零开始详解算法原理,debug模式逐行代码解读。适合准备就业和转行的同学们加入学习! 建议按照下列课程顺序来进行学习 (1)掌握深度学习必备经典网络架构 (2)深度框架实战方法 (3)计算机视觉与自然语言处理项目实战。(按照课程排列顺序即可)

HoloLens2开发入门教程

本课程为HoloLens2开发入门教程,讲解部署开发环境,安装VS2019,Unity版本,Windows SDK,创建Unity项目,讲解如何使用MRTK,编辑器模拟手势交互,打包VS工程并编译部署应用到HoloLens上等。

几率大的Redis面试题(含答案)

本文的面试题如下: Redis 持久化机制 缓存雪崩、缓存穿透、缓存预热、缓存更新、缓存降级等问题 热点数据和冷数据是什么 Memcache与Redis的区别都有哪些? 单线程的redis为什么这么快 redis的数据类型,以及每种数据类型的使用场景,Redis 内部结构 redis的过期策略以及内存淘汰机制【~】 Redis 为什么是单线程的,优点 如何解决redis的并发竞争key问题 Red...

MFC一站式终极全套课程包

该套餐共包含从C小白到C++到MFC的全部课程,整套学下来绝对成为一名C++大牛!!!

【数据结构与算法综合实验】欢乐连连看(C++ & MFC)案例

这是武汉理工大学计算机学院数据结构与算法综合实验课程的第三次项目:欢乐连连看(C++ & MFC)迭代开发代码。运行环境:VS2017。已经实现功能:开始游戏、消子、判断胜负、提示、重排、计时、帮助。

YOLOv3目标检测实战:训练自己的数据集

YOLOv3是一种基于深度学习的端到端实时目标检测方法,以速度快见长。本课程将手把手地教大家使用labelImg标注和使用YOLOv3训练自己的数据集。课程分为三个小项目:足球目标检测(单目标检测)、梅西目标检测(单目标检测)、足球和梅西同时目标检测(两目标检测)。 本课程的YOLOv3使用Darknet,在Ubuntu系统上做项目演示。包括:安装Darknet、给自己的数据集打标签、整理自己的数据集、修改配置文件、训练自己的数据集、测试训练出的网络模型、性能统计(mAP计算和画出PR曲线)和先验框聚类。 Darknet是使用C语言实现的轻型开源深度学习框架,依赖少,可移植性好,值得深入探究。 除本课程《YOLOv3目标检测实战:训练自己的数据集》外,本人推出了有关YOLOv3目标检测的系列课程,请持续关注该系列的其它课程视频,包括: 《YOLOv3目标检测实战:交通标志识别》 《YOLOv3目标检测:原理与源码解析》 《YOLOv3目标检测:网络模型改进方法》 敬请关注并选择学习!

u-boot-2015.07.tar.bz2

uboot-2015-07最新代码,喜欢的朋友请拿去

相关热词 c# 按行txt c#怎么扫条形码 c#打包html c# 实现刷新数据 c# 两个自定义控件重叠 c#浮点类型计算 c#.net 中文乱码 c# 时间排序 c# 必备书籍 c#异步网络通信
立即提问