spring boot + jpa访问数据库时报这个错,调用CrudRepository保存的时候 1C

java.lang.NullPointerException: null
at com.yd.cn.controller.SampleController.hello(SampleController.java:26) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_102]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_102]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_102]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_102]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:817) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:731) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:968) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:859) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) ~[servlet-api.jar:na]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:844) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[servlet-api.jar:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-websocket.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11]
at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:237) ~[spring-boot-actuator-1.3.3.RELEASE.jar:1.3.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11]
at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:112) ~[spring-boot-actuator-1.3.3.RELEASE.jar:1.3.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11]
at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:103) ~[spring-boot-actuator-1.3.3.RELEASE.jar:1.3.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[catalina.jar:8.5.11]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [catalina.jar:8.5.11]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:474) [catalina.jar:8.5.11]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [catalina.jar:8.5.11]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [catalina.jar:8.5.11]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [catalina.jar:8.5.11]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) [catalina.jar:8.5.11]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783) [tomcat-coyote.jar:8.5.11]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-coyote.jar:8.5.11]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:798) [tomcat-coyote.jar:8.5.11]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1434) [tomcat-coyote.jar:8.5.11]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-coyote.jar:8.5.11]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_102]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_102]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.5.11]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_102]
图片说明![图片说明](https://img-ask.csdn.net/upload/201708/22/1503380520_871584.png)图片说明

wugyl
wugyl 同样问题楼主如何解决的
7 个月之前 回复

3个回答

错误就是在第一行,,没有指向,没有你的代码,具体不知道是什么错误.你可以去百度搜一下第一行,结合你自己的代码,可以找出答案的

ava.lang.NullPointerException: null
at com.yd.cn.controller.SampleController.hello(SampleController.java:26) ~[classes/:na]

你这里空指针,是不是有对象没有实例化

SampleController.java:26

这个类的地26行,自己打断点很快就出来了

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
spring boot + jpa访问数据库时报这个错,调用CrudRepository保存的时候
java.lang.NullPointerException: null at com.yd.cn.controller.SampleController.hello(SampleController.java:26) ~[classes/:na] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_102] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_102] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_102] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_102] at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:817) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:731) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:968) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:859) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) ~[servlet-api.jar:na] at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:844) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[servlet-api.jar:na] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) ~[catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11] at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-websocket.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11] at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:237) ~[spring-boot-actuator-1.3.3.RELEASE.jar:1.3.3.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11] at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:112) ~[spring-boot-actuator-1.3.3.RELEASE.jar:1.3.3.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11] at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11] at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11] at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11] at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11] at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:103) ~[spring-boot-actuator-1.3.3.RELEASE.jar:1.3.3.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[catalina.jar:8.5.11] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[catalina.jar:8.5.11] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[catalina.jar:8.5.11] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [catalina.jar:8.5.11] at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:474) [catalina.jar:8.5.11] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [catalina.jar:8.5.11] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [catalina.jar:8.5.11] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [catalina.jar:8.5.11] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) [catalina.jar:8.5.11] at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783) [tomcat-coyote.jar:8.5.11] at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-coyote.jar:8.5.11] at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:798) [tomcat-coyote.jar:8.5.11] at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1434) [tomcat-coyote.jar:8.5.11] at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-coyote.jar:8.5.11] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_102] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_102] at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.5.11] at java.lang.Thread.run(Thread.java:745) [na:1.8.0_102] ![图片说明](https://img-ask.csdn.net/upload/201708/22/1503380371_349769.png)![![图片说明](https://img-ask.csdn.net/upload/201708/22/1503380520_871584.png)图片说明](https://img-ask.csdn.net/upload/201708/22/1503380462_232925.png)
spring boot jpa 多表联查
spring boot JPA 中多表联查怎么搞?关联查A表和B表中的字段,怎么返回结果集?
spring boot jpa 动态参数传表名,执行时自动添加单引号
spring boot jpa 动态参数传表名,执行时自动添加单引号怎么办
Spring Boot 使用JPA连接MySQL数据库报错 is not mapped
小白向各位大侠求助: 创建Spring Boot 工程时,使用JPA连接MySQL数据库,查询时报错,报错信息如下: ``` 2018-06-04 06:34:44.959 ERROR 6116 --- [nio-8080-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.InvalidDataAccessApiUsageException: org.hibernate.hql.internal.ast.QuerySyntaxException: Person is not mapped [select t from Person t]; nested exception is java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: Person is not mapped [select t from Person t]] with root cause org.hibernate.hql.internal.ast.QuerySyntaxException: Person is not mapped at org.hibernate.hql.internal.ast.util.SessionFactoryHelper.requireClassPersister(SessionFactoryHelper.java:169) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.ast.tree.FromElementFactory.addFromElement(FromElementFactory.java:91) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.ast.tree.FromClause.addFromElement(FromClause.java:79) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.ast.HqlSqlWalker.createFromElement(HqlSqlWalker.java:326) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3706) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3595) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:720) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:576) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:313) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:261) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:266) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:189) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:141) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:115) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:77) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:153) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:553) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:662) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:23) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131] at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:350) ~[spring-orm-5.0.6.RELEASE.jar:5.0.6.RELEASE] at com.sun.proxy.$Proxy76.createQuery(Unknown Source) ~[na:na] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131] at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:304) ~[spring-orm-5.0.6.RELEASE.jar:5.0.6.RELEASE] at com.sun.proxy.$Proxy76.createQuery(Unknown Source) ~[na:na] at com.neuqsoft.demo.repository.impl.PersonDaoImpl.findAll(PersonDaoImpl.java:52) ~[classes/:na] at com.neuqsoft.demo.repository.impl.PersonDaoImpl$$FastClassBySpringCGLIB$$7895840c.invoke(<generated>) ~[classes/:na] at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746) ~[spring-aop-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688) ~[spring-aop-5.0.6.RELEASE.jar:5.0.6.RELEASE] at com.neuqsoft.demo.repository.impl.PersonDaoImpl$$EnhancerBySpringCGLIB$$182f86eb.findAll(<generated>) ~[classes/:na] at com.neuqsoft.demo.service.PersonService.findAll(PersonService.java:50) ~[classes/:na] at com.neuqsoft.demo.controller.PersonController.getPseronList(PersonController.java:59) ~[classes/:na] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131] at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131] at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.31.jar:8.5.31] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496) [tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790) [tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1468) [tomcat-embed-core-8.5.31.jar:8.5.31] at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.31.jar:8.5.31] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_131] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_131] at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.31.jar:8.5.31] at java.lang.Thread.run(Thread.java:748) [na:1.8.0_131] ``` 实体文件: ``` @Entity @Table(name = "person") public class Person { @Id @GeneratedValue(strategy = GenerationType.AUTO) private String id; @Column(name="name") private String name; @Column(name="sex") private String sex; @Column(name="tel") private String tel; @Column(name="address") private String address; @Column(name="age") private String age; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public String getTel() { return tel; } public void setTel(String tel) { this.tel = tel; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } public String getAge() { return age; } public void setAge(String age) { this.age = age; } } ``` 数据库表: ![图片说明](https://img-ask.csdn.net/upload/201806/04/1528064584_339931.jpg) DAO文件: ``` package com.neuqsoft.demo.repository.impl; import java.util.List; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Repository; import com.neuqsoft.demo.entity.Person; import com.neuqsoft.demo.repository.PersonDao; @Repository public class PersonDaoImpl implements PersonDao { @Autowired @PersistenceContext private EntityManager entityManager; @Override public List<Person> findAll() { return this.entityManager.createQuery("select t from Person t").getResultList(); } } ``` 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 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.neuqsoft</groupId> <artifactId>DemoJPAForSpringBoot</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <name>DemoJPAForSpringBoot</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.2.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <!-- custom renw --> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.1.0</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> ``` application.properties: ``` #mysql #datasource spring.datasource.driver-class-name=com.mysql.jdbc.Driver spring.datasource.url=jdbc:mysql://localhost:3306/forspringboot?useSSL=false spring.datasource.username=root spring.datasource.password=1qaz!QAZ spring.jpa.show-sql= true ```
Spring Data JPA 中的findOne方法如何使用string类型作参数
## 先上图 ![图片说明](https://img-ask.csdn.net/upload/202001/20/1579504915_6319.png) 我在使用SpringBoot 实战这本书学习时,手写其中的案例。 却发现Spring Data JPA中的findOne方法不能接收一个username这个String类型的参数。(ReaderRepository是一个JPA的接口) 求大神指定解决方法。
Spring boot + Spring Data JPA + Hibernate缓存问题
如题,项目框架为Spring boot + Spring Data JPA + Hibernate,hibernate中有Query.list()和query.iterator()方法,其中query.iterator()方法去查询时会用到缓存,返回的参数类型是Iterator,如果使用Spring Data JPA+hibernate如何实现查询一个list使用到缓存呢,JPA中的PagingAndSortingRepository接口中的findAll()方法返回的Iterator类型好像和query.iterator()的效果不一样,哪个哥们可以解答下,万分感激!
Spring Boot Jpa 多表关联查询问题
jpa单表分页查询很简单一个自带的findall方法就搞定。那么类似下面的多表关联分页查询该如何解决呢? SELECT t.id,t.co_name,e.experiment_code,e.experiment_name FROM tb_component t, tb_component_flow tf, tb_experiment_apply e WHERE t.id = tf.component_id AND tf.experiment_apply_id = e.id AND e.experiment_name LIKE '%实验%' _***跪求大佬们在线指点。**
play-spring-jpa 连接数据库出错
persistence.xml中配置 <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd" version="2.0"> <persistence-unit name="default" transaction-type="JTA"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <jta-data-source>DefaultDS</jta-data-source> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/> <property name="hibernate.hbm2ddl.auto" value="update"/> </properties> </persistence-unit> </persistence> 报错内容 play.api.UnexpectedException: Unexpected exception[UnsatisfiedDependencyExceptio n: Error creating bean with name 'application' defined in file [D:\play-spring-d ata-jpa\target\scala-2.10\classes\controllers\Application.class]: Unsatisfied de pendency expressed through constructor argument with index 0 of type [models.Per sonRepository]: : Error creating bean with name 'personRepository': Cannot creat e inner bean '(inner bean)' of type [org.springframework.orm.jpa.SharedEntityMan agerCreator] while setting bean property 'entityManager'; nested exception is or g.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#1': Cannot resolve reference to bean 'entityManagerFactory' w hile setting constructor argument; nested exception is org.springframework.beans .factory.BeanCreationException: Error creating bean with name 'entityManagerFact ory' defined in class Global$SpringDataJpaConfiguration: Instantiation of bean f ailed; nested exception is org.springframework.beans.factory.BeanDefinitionStore Exception: Factory method [public javax.persistence.EntityManagerFactory Global$ SpringDataJpaConfiguration.entityManagerFactory()] threw exception; nested excep tion is javax.persistence.PersistenceException: [PersistenceUnit: default] Unabl e to build EntityManagerFactory; nested exception is org.springframework.beans.f actory.BeanCreationException: Error creating bean with name 'personRepository': Cannot create inner bean '(inner bean)' of type [org.springframework.orm.jpa.Sha redEntityManagerCreator] while setting bean property 'entityManager'; nested exc eption is org.springframework.beans.factory.BeanCreationException: Error creatin g bean with name '(inner bean)#1': Cannot resolve reference to bean 'entityManag erFactory' while setting constructor argument; nested exception is org.springfra mework.beans.factory.BeanCreationException: Error creating bean with name 'entit yManagerFactory' defined in class Global$SpringDataJpaConfiguration: Instantiati on of bean failed; nested exception is org.springframework.beans.factory.BeanDef initionStoreException: Factory method [public javax.persistence.EntityManagerFac tory Global$SpringDataJpaConfiguration.entityManagerFactory()] threw exception; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: de fault] Unable to build EntityManagerFactory] at play.core.ReloadableApplication$$anonfun$get$1$$anonfun$apply$1$$anon fun$1.apply(ApplicationProvider.scala:148) ~[play_2.10.jar:2.2.3] at play.core.ReloadableApplication$$anonfun$get$1$$anonfun$apply$1$$anon fun$1.apply(ApplicationProvider.scala:112) ~[play_2.10.jar:2.2.3] at scala.Option.map(Option.scala:145) ~[scala-library.jar:na] at play.core.ReloadableApplication$$anonfun$get$1$$anonfun$apply$1.apply (ApplicationProvider.scala:112) ~[play_2.10.jar:2.2.3] at play.core.ReloadableApplication$$anonfun$get$1$$anonfun$apply$1.apply (ApplicationProvider.scala:110) ~[play_2.10.jar:2.2.3] at scala.util.Success.flatMap(Try.scala:200) ~[scala-library.jar:na] Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Err or creating bean with name 'application' defined in file [D:\play-spring-data-jp a\target\scala-2.10\classes\controllers\Application.class]: Unsatisfied dependen cy expressed through constructor argument with index 0 of type [models.PersonRep ository]: : Error creating bean with name 'personRepository': Cannot create inne r bean '(inner bean)' of type [org.springframework.orm.jpa.SharedEntityManagerCr eator] while setting bean property 'entityManager'; nested exception is org.spri ngframework.beans.factory.BeanCreationException: Error creating bean with name ' (inner bean)#1': Cannot resolve reference to bean 'entityManagerFactory' while s etting constructor argument; nested exception is org.springframework.beans.facto ry.BeanCreationException: Error creating bean with name 'entityManagerFactory' d efined in class Global$SpringDataJpaConfiguration: Instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanDefinitionStoreExcept ion: Factory method [public javax.persistence.EntityManagerFactory Global$Spring DataJpaConfiguration.entityManagerFactory()] threw exception; nested exception i s javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to b uild EntityManagerFactory; nested exception is org.springframework.beans.factory .BeanCreationException: Error creating bean with name 'personRepository': Cannot create inner bean '(inner bean)' of type [org.springframework.orm.jpa.SharedEnt ityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#1': Cannot resolve reference to bean 'entityManagerFact ory' while setting constructor argument; nested exception is org.springframework .beans.factory.BeanCreationException: Error creating bean with name 'entityManag erFactory' defined in class Global$SpringDataJpaConfiguration: Instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanDefinitio nStoreException: Factory method [public javax.persistence.EntityManagerFactory G lobal$SpringDataJpaConfiguration.entityManagerFactory()] threw exception; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build EntityManagerFactory at org.springframework.beans.factory.support.ConstructorResolver.createA rgumentArray(ConstructorResolver.java:730) ~[spring-beans.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.ConstructorResolver.autowir eConstructor(ConstructorResolver.java:196) ~[spring-beans.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1045) ~[spri ng-beans.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:949) ~[spring -beans.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.doCreateBean(AbstractAutowireCapableBeanFactory.java:487) ~[spring-beans .jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.createBean(AbstractAutowireCapableBeanFactory.java:458) ~[spring-beans.j ar:3.2.3.RELEASE] Caused by: org.springframework.beans.factory.BeanCreationException: Error creati ng bean with name 'personRepository': Cannot create inner bean '(inner bean)' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bea n property 'entityManager'; nested exception is org.springframework.beans.factor y.BeanCreationException: Error creating bean with name '(inner bean)#1': Cannot resolve reference to bean 'entityManagerFactory' while setting constructor argum ent; nested exception is org.springframework.beans.factory.BeanCreationException : Error creating bean with name 'entityManagerFactory' defined in class Global$S pringDataJpaConfiguration: Instantiation of bean failed; nested exception is org .springframework.beans.factory.BeanDefinitionStoreException: Factory method [pub lic javax.persistence.EntityManagerFactory Global$SpringDataJpaConfiguration.ent ityManagerFactory()] threw exception; nested exception is javax.persistence.Pers istenceException: [PersistenceUnit: default] Unable to build EntityManagerFactor y at org.springframework.beans.factory.support.BeanDefinitionValueResolver .resolveInnerBean(BeanDefinitionValueResolver.java:282) ~[spring-beans.jar:3.2.3 .RELEASE] at org.springframework.beans.factory.support.BeanDefinitionValueResolver .resolveValueIfNecessary(BeanDefinitionValueResolver.java:126) ~[spring-beans.ja r:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1387) ~[spri ng-beans.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.populateBean(AbstractAutowireCapableBeanFactory.java:1128) ~[spring-bean s.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) ~[spring-beans .jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.createBean(AbstractAutowireCapableBeanFactory.java:458) ~[spring-beans.j ar:3.2.3.RELEASE] Caused by: org.springframework.beans.factory.BeanCreationException: Error creati ng bean with name '(inner bean)#1': Cannot resolve reference to bean 'entityMana gerFactory' while setting constructor argument; nested exception is org.springfr amework.beans.factory.BeanCreationException: Error creating bean with name 'enti tyManagerFactory' defined in class Global$SpringDataJpaConfiguration: Instantiat ion of bean failed; nested exception is org.springframework.beans.factory.BeanDe finitionStoreException: Factory method [public javax.persistence.EntityManagerFa ctory Global$SpringDataJpaConfiguration.entityManagerFactory()] threw exception; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: d efault] Unable to build EntityManagerFactory at org.springframework.beans.factory.support.BeanDefinitionValueResolver .resolveReference(BeanDefinitionValueResolver.java:329) ~[spring-beans.jar:3.2.3 .RELEASE] at org.springframework.beans.factory.support.BeanDefinitionValueResolver .resolveValueIfNecessary(BeanDefinitionValueResolver.java:107) ~[spring-beans.ja r:3.2.3.RELEASE] at org.springframework.beans.factory.support.ConstructorResolver.resolve ConstructorArguments(ConstructorResolver.java:615) ~[spring-beans.jar:3.2.3.RELE ASE] at org.springframework.beans.factory.support.ConstructorResolver.instant iateUsingFactoryMethod(ConstructorResolver.java:441) ~[spring-beans.jar:3.2.3.RE LEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:10 25) ~[spring-beans.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:921) ~[spring -beans.jar:3.2.3.RELEASE] Caused by: org.springframework.beans.factory.BeanCreationException: Error creati ng bean with name 'entityManagerFactory' defined in class Global$SpringDataJpaCo nfiguration: Instantiation of bean failed; nested exception is org.springframewo rk.beans.factory.BeanDefinitionStoreException: Factory method [public javax.pers istence.EntityManagerFactory Global$SpringDataJpaConfiguration.entityManagerFact ory()] threw exception; nested exception is javax.persistence.PersistenceExcepti on: [PersistenceUnit: default] Unable to build EntityManagerFactory at org.springframework.beans.factory.support.ConstructorResolver.instant iateUsingFactoryMethod(ConstructorResolver.java:581) ~[spring-beans.jar:3.2.3.RE LEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:10 25) ~[spring-beans.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:921) ~[spring -beans.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.doCreateBean(AbstractAutowireCapableBeanFactory.java:487) ~[spring-beans .jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.createBean(AbstractAutowireCapableBeanFactory.java:458) ~[spring-beans.j ar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory$1.getOb ject(AbstractBeanFactory.java:295) ~[spring-beans.jar:3.2.3.RELEASE] Caused by: org.springframework.beans.factory.BeanDefinitionStoreException: Facto ry method [public javax.persistence.EntityManagerFactory Global$SpringDataJpaCon figuration.entityManagerFactory()] threw exception; nested exception is javax.pe rsistence.PersistenceException: [PersistenceUnit: default] Unable to build Entit yManagerFactory at org.springframework.beans.factory.support.SimpleInstantiationStrategy .instantiate(SimpleInstantiationStrategy.java:181) ~[spring-beans.jar:3.2.3.RELE ASE] at org.springframework.beans.factory.support.ConstructorResolver.instant iateUsingFactoryMethod(ConstructorResolver.java:570) ~[spring-beans.jar:3.2.3.RE LEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:10 25) ~[spring-beans.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:921) ~[spring -beans.jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.doCreateBean(AbstractAutowireCapableBeanFactory.java:487) ~[spring-beans .jar:3.2.3.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBean Factory.createBean(AbstractAutowireCapableBeanFactory.java:458) ~[spring-beans.j ar:3.2.3.RELEASE] Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Un able to build EntityManagerFactory at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Con figuration.java:915) ~[hibernate-entitymanager-3.6.10.Final.jar:3.6.10.Final] at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(Hib ernatePersistence.java:57) ~[hibernate-entitymanager-3.6.10.Final.jar:3.6.10.Fin al] at javax.persistence.Persistence.createEntityManagerFactory(Persistence. java:63) ~[hibernate-jpa-2.0-api.jar:1.0.1.Final] at javax.persistence.Persistence.createEntityManagerFactory(Persistence. java:47) ~[hibernate-jpa-2.0-api.jar:1.0.1.Final] at Global$SpringDataJpaConfiguration.entityManagerFactory(Global.java:76 ) ~[na:na] at Global$SpringDataJpaConfiguration$$EnhancerByCGLIB$$715a97cd.CGLIB$en tityManagerFactory$0(<generated>) ~[na:na] Caused by: org.hibernate.HibernateException: The chosen transaction strategy req uires access to the JTA TransactionManager at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java: 390) ~[hibernate-core-3.6.10.Final.jar:3.6.10.Final] at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.jav a:1872) ~[hibernate-core-3.6.10.Final.jar:3.6.10.Final] at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Con figuration.java:906) ~[hibernate-entitymanager-3.6.10.Final.jar:3.6.10.Final] at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(Hib ernatePersistence.java:57) ~[hibernate-entitymanager-3.6.10.Final.jar:3.6.10.Fin al] at javax.persistence.Persistence.createEntityManagerFactory(Persistence. java:63) ~[hibernate-jpa-2.0-api.jar:1.0.1.Final] at javax.persistence.Persistence.createEntityManagerFactory(Persistence. java:47) ~[hibernate-jpa-2.0-api.jar:1.0.1.Final]
spring boot jpa 原生SQL
在使用jpa进行持久层操作时,使用原生SQL, @Modifying @Query(nativeQuery=true,value="UPDATE table SET name=?1 where id=?2") void modify(String name ,String id); ``` 我想知道,如果修改字段较多,该怎么写?
spring data jpa 拦截
spring boot项目,数据层spring data jpa 现在想在数据层把个人信息的敏感字段加密?因为项目过大,如何事项在查询语句执行之前增加拦截,将查询参数进行加密,及获取数据后将查询数据进行解密。
spring data jpa 第一行代码我save了某一个表的数据,看到数据库数据变了。
spring data jpa 第一行代码我save了某一个表的数据,看到数据库数据变了。 我第二行去查询这个表的数据,得到的却是没保存数据之前的数据。 再刷新页面就得到了现在数据库的数据是咋回事呢
Spring Data jpa+Mongodb查询全部数据出错
代码: List<Comment> comments = commentDao.findAll(); findAll为继承自MongoRepository的方法 报错: Caused by: com.mongodb.MongoQueryException: Query failed with error code 2 and error message 'Field 'locale' is invalid in: { locale: "comment" }' on server localhost:27017 at com.mongodb.operation.FindOperation$1.call(FindOperation.java:735) at com.mongodb.operation.FindOperation$1.call(FindOperation.java:725) at com.mongodb.operation.OperationHelper.withReadConnectionSource(OperationHelper.java:463) at com.mongodb.operation.FindOperation.execute(FindOperation.java:725) at com.mongodb.operation.FindOperation.execute(FindOperation.java:89) at com.mongodb.client.internal.MongoClientDelegate$DelegateOperationExecutor.execute(MongoClientDelegate.java:189) at com.mongodb.client.internal.MongoIterableImpl.execute(MongoIterableImpl.java:143) at com.mongodb.client.internal.MongoIterableImpl.iterator(MongoIterableImpl.java:92) at org.springframework.data.mongodb.core.MongoTemplate.executeFindMultiInternal(MongoTemplate.java:2793) ... 86 more 试过换工程、换数据库、换表、换版本,依旧没有解决,而且几乎搜不到这个错误。
Spring data jpa ExampleMatcher
spring data jpa如何用ExampleMatcher写一个不等于查询条件
spring boot jpa 懒加载无效
代码如下,实体类未作任何特殊处理,只是主表关联子表,查询主表时自动将子表查询出来,懒加载配置没起作用。 @OneToOne(cascade = CascadeType.ALL,fetch = FetchType.LAZY ) @PrimaryKeyJoinColumn private BatchLogAmount batchLogAmount;
使用 spring data jpa
使用spring data jpa 报错Page 1 of 0 containing UNKNOWN instances 如果是 自己添加数据可以查询出来 而数据库以前存在的数据查询不到 大神救急!!!
spring data jpa如何自定义insert sql?批量保存数据
框架spring data jpa + hibernate 例如我想一个inset插入多条数据 ``` INSERT INTO tableName (column1,column) VALUES (value1,value2),(value3,value4),(value5,value6); ``` 插入的条数是不固定的, 将整句sql作为参数,用spring data jpa 的@Query注解进行插入是无法解析出来sql的。 请问我还有什么办法能插入整句sql? 在spring data jpa框架中 save()方法确实可以插入n条数据的集合,但是底层原理依然是一个一个的保存, 并且前后会访问2n次数据库。所以这个方法不考虑。
mybatis和jpa都是需要实体操作数据库的吗?
现在需要写个系统,但是公司要求用存储过程,直接拿参数请求存储过程 hibernate可以实现 mybatis和jpa可以吗? 还有一个问题是,数据库表正在使用,直接添加表的字段会不会对程序造成影响?
spring Data Jpa 项目发布linux sql大写 报错问题
spring Data Jpa 项目 本地windows开发 正常 发布到linux之后报找不到表错误 原因是hibernate将表名大写了 请问这个怎么解决 已找到问题 不是hibernate的 是mysql没设置不区分大小写 在my.ini或者my.cnf 下设置lower_case_table_names=1 就好了
spring data jpa怎么配置?
spring data jpa怎么配置? spring data jpa怎么配置? spring data jpa怎么配置? spring data jpa怎么配置?
Java学习的正确打开方式
在博主认为,对于入门级学习java的最佳学习方法莫过于视频+博客+书籍+总结,前三者博主将淋漓尽致地挥毫于这篇博客文章中,至于总结在于个人,实际上越到后面你会发现学习的最好方式就是阅读参考官方文档其次就是国内的书籍,博客次之,这又是一个层次了,这里暂时不提后面再谈。博主将为各位入门java保驾护航,各位只管冲鸭!!!上天是公平的,只要不辜负时间,时间自然不会辜负你。 何谓学习?博主所理解的学习,它是一个过程,是一个不断累积、不断沉淀、不断总结、善于传达自己的个人见解以及乐于分享的过程。
程序员必须掌握的核心算法有哪些?
由于我之前一直强调数据结构以及算法学习的重要性,所以就有一些读者经常问我,数据结构与算法应该要学习到哪个程度呢?,说实话,这个问题我不知道要怎么回答你,主要取决于你想学习到哪些程度,不过针对这个问题,我稍微总结一下我学过的算法知识点,以及我觉得值得学习的算法。这些算法与数据结构的学习大多数是零散的,并没有一本把他们全部覆盖的书籍。下面是我觉得值得学习的一些算法以及数据结构,当然,我也会整理一些看过...
有哪些让程序员受益终生的建议
从业五年多,辗转两个大厂,出过书,创过业,从技术小白成长为基层管理,联合几个业内大牛回答下这个问题,希望能帮到大家,记得帮我点赞哦。 敲黑板!!!读了这篇文章,你将知道如何才能进大厂,如何实现财务自由,如何在工作中游刃有余,这篇文章很长,但绝对是精品,记得帮我点赞哦!!!! 一腔肺腑之言,能看进去多少,就看你自己了!!! 目录: 在校生篇: 为什么要尽量进大厂? 如何选择语言及方...
大学四年自学走来,这些私藏的实用工具/学习网站我贡献出来了
大学四年,看课本是不可能一直看课本的了,对于学习,特别是自学,善于搜索网上的一些资源来辅助,还是非常有必要的,下面我就把这几年私藏的各种资源,网站贡献出来给你们。主要有:电子书搜索、实用工具、在线视频学习网站、非视频学习网站、软件下载、面试/求职必备网站。 注意:文中提到的所有资源,文末我都给你整理好了,你们只管拿去,如果觉得不错,转发、分享就是最大的支持了。 一、电子书搜索 对于大部分程序员...
linux系列之常用运维命令整理笔录
本博客记录工作中需要的linux运维命令,大学时候开始接触linux,会一些基本操作,可是都没有整理起来,加上是做开发,不做运维,有些命令忘记了,所以现在整理成博客,当然vi,文件操作等就不介绍了,慢慢积累一些其它拓展的命令,博客不定时更新 free -m 其中:m表示兆,也可以用g,注意都要小写 Men:表示物理内存统计 total:表示物理内存总数(total=used+free) use...
比特币原理详解
一、什么是比特币 比特币是一种电子货币,是一种基于密码学的货币,在2008年11月1日由中本聪发表比特币白皮书,文中提出了一种去中心化的电子记账系统,我们平时的电子现金是银行来记账,因为银行的背后是国家信用。去中心化电子记账系统是参与者共同记账。比特币可以防止主权危机、信用风险。其好处不多做赘述,这一层面介绍的文章很多,本文主要从更深层的技术原理角度进行介绍。 二、问题引入 假设现有4个人...
程序员接私活怎样防止做完了不给钱?
首先跟大家说明一点,我们做 IT 类的外包开发,是非标品开发,所以很有可能在开发过程中会有这样那样的需求修改,而这种需求修改很容易造成扯皮,进而影响到费用支付,甚至出现做完了项目收不到钱的情况。 那么,怎么保证自己的薪酬安全呢? 我们在开工前,一定要做好一些证据方面的准备(也就是“讨薪”的理论依据),这其中最重要的就是需求文档和验收标准。一定要让需求方提供这两个文档资料作为开发的基础。之后开发...
网页实现一个简单的音乐播放器(大佬别看。(⊙﹏⊙))
今天闲着无事,就想写点东西。然后听了下歌,就打算写个播放器。 于是乎用h5 audio的加上js简单的播放器完工了。 演示地点演示 html代码如下` music 这个年纪 七月的风 音乐 ` 然后就是css`*{ margin: 0; padding: 0; text-decoration: none; list-...
Python十大装B语法
Python 是一种代表简单思想的语言,其语法相对简单,很容易上手。不过,如果就此小视 Python 语法的精妙和深邃,那就大错特错了。本文精心筛选了最能展现 Python 语法之精妙的十个知识点,并附上详细的实例代码。如能在实战中融会贯通、灵活使用,必将使代码更为精炼、高效,同时也会极大提升代码B格,使之看上去更老练,读起来更优雅。
数据库优化 - SQL优化
以实际SQL入手,带你一步一步走上SQL优化之路!
2019年11月中国大陆编程语言排行榜
2019年11月2日,我统计了某招聘网站,获得有效程序员招聘数据9万条。针对招聘信息,提取编程语言关键字,并统计如下: 编程语言比例 rank pl_ percentage 1 java 33.62% 2 cpp 16.42% 3 c_sharp 12.82% 4 javascript 12.31% 5 python 7.93% 6 go 7.25% 7 p...
通俗易懂地给女朋友讲:线程池的内部原理
餐盘在灯光的照耀下格外晶莹洁白,女朋友拿起红酒杯轻轻地抿了一小口,对我说:“经常听你说线程池,到底线程池到底是个什么原理?”
《奇巧淫技》系列-python!!每天早上八点自动发送天气预报邮件到QQ邮箱
将代码部署服务器,每日早上定时获取到天气数据,并发送到邮箱。 也可以说是一个小型人工智障。 知识可以运用在不同地方,不一定非是天气预报。
经典算法(5)杨辉三角
杨辉三角 是经典算法,这篇博客对它的算法思想进行了讲解,并有完整的代码实现。
英特尔不为人知的 B 面
从 PC 时代至今,众人只知在 CPU、GPU、XPU、制程、工艺等战场中,英特尔在与同行硬件芯片制造商们的竞争中杀出重围,且在不断的成长进化中,成为全球知名的半导体公司。殊不知,在「刚硬」的背后,英特尔「柔性」的软件早已经做到了全方位的支持与支撑,并持续发挥独特的生态价值,推动产业合作共赢。 而对于这一不知人知的 B 面,很多人将其称之为英特尔隐形的翅膀,虽低调,但是影响力却不容小觑。 那么,在...
腾讯算法面试题:64匹马8个跑道需要多少轮才能选出最快的四匹?
昨天,有网友私信我,说去阿里面试,彻底的被打击到了。问了为什么网上大量使用ThreadLocal的源码都会加上private static?他被难住了,因为他从来都没有考虑过这个问题。无独有偶,今天笔者又发现有网友吐槽了一道腾讯的面试题,我们一起来看看。 腾讯算法面试题:64匹马8个跑道需要多少轮才能选出最快的四匹? 在互联网职场论坛,一名程序员发帖求助到。二面腾讯,其中一个算法题:64匹...
面试官:你连RESTful都不知道我怎么敢要你?
干货,2019 RESTful最贱实践
为啥国人偏爱Mybatis,而老外喜欢Hibernate/JPA呢?
关于SQL和ORM的争论,永远都不会终止,我也一直在思考这个问题。昨天又跟群里的小伙伴进行了一番讨论,感触还是有一些,于是就有了今天这篇文。 声明:本文不会下关于Mybatis和JPA两个持久层框架哪个更好这样的结论。只是摆事实,讲道理,所以,请各位看官勿喷。 一、事件起因 关于Mybatis和JPA孰优孰劣的问题,争论已经很多年了。一直也没有结论,毕竟每个人的喜好和习惯是大不相同的。我也看...
白话阿里巴巴Java开发手册高级篇
不久前,阿里巴巴发布了《阿里巴巴Java开发手册》,总结了阿里巴巴内部实际项目开发过程中开发人员应该遵守的研发流程规范,这些流程规范在一定程度上能够保证最终的项目交付质量,通过在时间中总结模式,并推广给广大开发人员,来避免研发人员在实践中容易犯的错误,确保最终在大规模协作的项目中达成既定目标。 无独有偶,笔者去年在公司里负责升级和制定研发流程、设计模板、设计标准、代码标准等规范,并在实际工作中进行...
SQL-小白最佳入门sql查询一
不要偷偷的查询我的个人资料,即使你再喜欢我,也不要这样,真的不好;
redis分布式锁,面试官请随便问,我都会
文章有点长并且绕,先来个图片缓冲下! 前言 现在的业务场景越来越复杂,使用的架构也就越来越复杂,分布式、高并发已经是业务要求的常态。像腾讯系的不少服务,还有CDN优化、异地多备份等处理。 说到分布式,就必然涉及到分布式锁的概念,如何保证不同机器不同线程的分布式锁同步呢? 实现要点 互斥性,同一时刻,智能有一个客户端持有锁。 防止死锁发生,如果持有锁的客户端崩溃没有主动释放锁,也要保证锁可以正常释...
项目中的if else太多了,该怎么重构?
介绍 最近跟着公司的大佬开发了一款IM系统,类似QQ和微信哈,就是聊天软件。我们有一部分业务逻辑是这样的 if (msgType = "文本") { // dosomething } else if(msgType = "图片") { // doshomething } else if(msgType = "视频") { // doshomething } else { // doshom...
Nginx 原理和架构
Nginx 是一个免费的,开源的,高性能的 HTTP 服务器和反向代理,以及 IMAP / POP3 代理服务器。Nginx 以其高性能,稳定性,丰富的功能,简单的配置和低资源消耗而闻名。 Nginx 的整体架构 Nginx 里有一个 master 进程和多个 worker 进程。master 进程并不处理网络请求,主要负责调度工作进程:加载配置、启动工作进程及非停升级。worker 进程负责处...
Python 编程开发 实用经验和技巧
Python是一门很灵活的语言,也有很多实用的方法,有时候实现一个功能可以用多种方法实现,我这里总结了一些常用的方法和技巧,包括小数保留指定位小数、判断变量的数据类型、类方法@classmethod、制表符中文对齐、遍历字典、datetime.timedelta的使用等,会持续更新......
YouTube排名第一的励志英文演讲《Dream(梦想)》
Idon’t know what that dream is that you have, I don't care how disappointing it might have been as you've been working toward that dream,but that dream that you’re holding in your mind, that it’s po...
“狗屁不通文章生成器”登顶GitHub热榜,分分钟写出万字形式主义大作
一、垃圾文字生成器介绍 最近在浏览GitHub的时候,发现了这样一个骨骼清奇的雷人项目,而且热度还特别高。 项目中文名:狗屁不通文章生成器 项目英文名:BullshitGenerator 根据作者的介绍,他是偶尔需要一些中文文字用于GUI开发时测试文本渲染,因此开发了这个废话生成器。但由于生成的废话实在是太过富于哲理,所以最近已经被小伙伴们给玩坏了。 他的文风可能是这样的: 你发现,...
程序员:我终于知道post和get的区别
是一个老生常谈的话题,然而随着不断的学习,对于以前的认识有很多误区,所以还是需要不断地总结的,学而时习之,不亦说乎
《程序人生》系列-这个程序员只用了20行代码就拿了冠军
你知道的越多,你不知道的越多 点赞再看,养成习惯GitHub上已经开源https://github.com/JavaFamily,有一线大厂面试点脑图,欢迎Star和完善 前言 这一期不算《吊打面试官》系列的,所有没前言我直接开始。 絮叨 本来应该是没有这期的,看过我上期的小伙伴应该是知道的嘛,双十一比较忙嘛,要值班又要去帮忙拍摄年会的视频素材,还得搞个程序员一天的Vlog,还要写BU...
加快推动区块链技术和产业创新发展,2019可信区块链峰会在京召开
11月8日,由中国信息通信研究院、中国通信标准化协会、中国互联网协会、可信区块链推进计划联合主办,科技行者协办的2019可信区块链峰会将在北京悠唐皇冠假日酒店开幕。   区块链技术被认为是继蒸汽机、电力、互联网之后,下一代颠覆性的核心技术。如果说蒸汽机释放了人类的生产力,电力解决了人类基本的生活需求,互联网彻底改变了信息传递的方式,区块链作为构造信任的技术有重要的价值。   1...
Java世界最常用的工具类库
Apache Commons Apache Commons有很多子项目 Google Guava 参考博客
程序员把地府后台管理系统做出来了,还有3.0版本!12月7号最新消息:已在开发中有github地址
第一幕:缘起 听说阎王爷要做个生死簿后台管理系统,我们派去了一个程序员…… 996程序员做的梦: 第一场:团队招募 为了应对地府管理危机,阎王打算找“人”开发一套地府后台管理系统,于是就在地府总经办群中发了项目需求。 话说还是中国电信的信号好,地府都是满格,哈哈!!! 经常会有外行朋友问:看某网站做的不错,功能也简单,你帮忙做一下? 而这次,面对这样的需求,这个程序员...
相关热词 c# 图片上传 c# gdi 占用内存 c#中遍历字典 c#控制台模拟dos c# 斜率 最小二乘法 c#进程延迟 c# mysql完整项目 c# grid 总行数 c# web浏览器插件 c# xml 生成xsd
立即提问