错误详情： ```### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ### The error may involve defaultParameterMap ### The error occurred while setting parameters ### SQL: insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '吕试听'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '吕试听') - ?, ?,?, ?,?,?,?) insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '3'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '3') - ?, ?,?, ?,?,?,?) ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ] - (28462 ms) - 2019-6-3 22:35:45[DEBUG](JakartaCommonsLoggingImpl.java:46) Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@23103ebd] - (28463 ms) - 2019-6-3 22:35:45[DEBUG](DataSourceUtils.java:327) Returning JDBC Connection to DataSource - (28468 ms) - 2019-6-3 22:35:45[DEBUG](AbstractHandlerExceptionResolver.java:132) Resolving exception from handler [public java.lang.String com.dms.controller.monthlyinfo.CourseInfoController.courseInfoSave(com.dms.pojo.Course,javax.servlet.http.HttpSession,javax.servlet.http.HttpServletRequest,java.lang.String)]: org.springframework.jdbc.BadSqlGrammarException: ### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ### The error may involve defaultParameterMap ### The error occurred while setting parameters ### SQL: insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '吕试听'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '吕试听') - ?, ?,?, ?,?,?,?) insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '3'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '3') - ?, ?,?, ?,?,?,?) ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ; bad SQL grammar []; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 - (28483 ms) - 2019-6-3 22:35:45[DEBUG](AbstractHandlerExceptionResolver.java:132) Resolving exception from handler [public java.lang.String com.dms.controller.monthlyinfo.CourseInfoController.courseInfoSave(com.dms.pojo.Course,javax.servlet.http.HttpSession,javax.servlet.http.HttpServletRequest,java.lang.String)]: org.springframework.jdbc.BadSqlGrammarException: ### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ### The error may involve defaultParameterMap ### The error occurred while setting parameters ### SQL: insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '吕试听'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '吕试听') - ?, ?,?, ?,?,?,?) insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '3'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '3') - ?, ?,?, ?,?,?,?) ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ; bad SQL grammar []; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 - (28484 ms) - 2019-6-3 22:35:45[DEBUG](AbstractHandlerExceptionResolver.java:132) Resolving exception from handler [public java.lang.String com.dms.controller.monthlyinfo.CourseInfoController.courseInfoSave(com.dms.pojo.Course,javax.servlet.http.HttpSession,javax.servlet.http.HttpServletRequest,java.lang.String)]: org.springframework.jdbc.BadSqlGrammarException: ### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ### The error may involve defaultParameterMap ### The error occurred while setting parameters ### SQL: insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '吕试听'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '吕试听') - ?, ?,?, ?,?,?,?) insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '3'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '3') - ?, ?,?, ?,?,?,?) ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ; bad SQL grammar []; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 - (28507 ms) - 2019-6-3 22:35:45[DEBUG](AbstractHandlerExceptionResolver.java:132) Resolving exception from handler [public java.lang.String com.dms.controller.monthlyinfo.CourseInfoController.courseInfoSave(com.dms.pojo.Course,javax.servlet.http.HttpSession,javax.servlet.http.HttpServletRequest,java.lang.String)]: org.springframework.jdbc.BadSqlGrammarException: ### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ### The error may involve defaultParameterMap ### The error occurred while setting parameters ### SQL: insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '吕试听'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '吕试听') - ?, ?,?, ?,?,?,?) insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '3'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '3') - ?, ?,?, ?,?,?,?) ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ; bad SQL grammar []; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 - (28507 ms) - 2019-6-3 22:35:45[DEBUG](AbstractHandlerExceptionResolver.java:132) Resolving exception from handler [public java.lang.String com.dms.controller.monthlyinfo.CourseInfoController.courseInfoSave(com.dms.pojo.Course,javax.servlet.http.HttpSession,javax.servlet.http.HttpServletRequest,java.lang.String)]: org.springframework.jdbc.BadSqlGrammarException: ### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ### The error may involve defaultParameterMap ### The error occurred while setting parameters ### SQL: insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '吕试听'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '吕试听') - ?, ?,?, ?,?,?,?) insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '3'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '3') - ?, ?,?, ?,?,?,?) ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ; bad SQL grammar []; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 - (28513 ms) - 2019-6-3 22:35:45[DEBUG](AbstractHandlerExceptionResolver.java:132) Resolving exception from handler [public java.lang.String com.dms.controller.monthlyinfo.CourseInfoController.courseInfoSave(com.dms.pojo.Course,javax.servlet.http.HttpSession,javax.servlet.http.HttpServletRequest,java.lang.String)]: org.springframework.jdbc.BadSqlGrammarException: ### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ### The error may involve defaultParameterMap ### The error occurred while setting parameters ### SQL: insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '吕试听'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '吕试听') - ?, ?,?, ?,?,?,?) insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '3'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '3') - ?, ?,?, ?,?,?,?) ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ; bad SQL grammar []; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 - (28514 ms) - 2019-6-3 22:35:45[DEBUG](FrameworkServlet.java:976) Could not complete request org.springframework.jdbc.BadSqlGrammarException: ### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ### The error may involve defaultParameterMap ### The error occurred while setting parameters ### SQL: insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '吕试听'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '吕试听') - ?, ?,?, ?,?,?,?) insert into expense_info(cId,sId,expenseDate,expenseWeek,expenseSchoolTime,expenseCoach,createdName,expenseSurplusClassHour,expenseCoursesContent,expenseTeachResult,createdBy,creationDate,modifyBy,modifyDate) values( (select max(id) from course_info), (select s.id from student_info s where s.studentName = '3'), ?,?,?,?,? (select studentClassHourNum from student_info where studentName = '3') - ?, ?,?, ?,?,?,?) ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 ; bad SQL grammar []; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 at org.springframework.jdbc.support.SQLErrorCodeSQLExceptionTranslator.doTranslate(SQLErrorCodeSQLExceptionTranslator.java:237) at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:72) at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:71) at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:364) at com.sun.proxy.$Proxy9.insert(Unknown Source) at org.mybatis.spring.SqlSessionTemplate.insert(SqlSessionTemplate.java:236) at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:46) at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:43) at com.sun.proxy.$Proxy11.addExpenseInfo(Unknown Source) at com.dms.service.course.impl.CourseServiceImpl.addExpenseInfo(CourseServiceImpl.java:52) at com.dms.controller.monthlyinfo.CourseInfoController.courseInfoSave(CourseInfoController.java:375) 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.invoke(InvocableHandlerMethod.java:215) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:743) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:672) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:82) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:919) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:851) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:953) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:855) at javax.servlet.http.HttpServlet.service(HttpServlet.java:660) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:829) at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:106) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:200) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748) Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(select studentClassHourNum from student_info where studentName = '???è?????') -' at line 6 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at com.mysql.jdbc.Util.handleNewInstance(Util.java:353) at com.mysql.jdbc.Util.getInstance(Util.java:336) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1031) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:957) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2938) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1601) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1710) at com.mysql.jdbc.Connection.execSQL(Connection.java:2436) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1402) at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:977) at org.apache.commons.dbcp.DelegatingPreparedStatement.execute(DelegatingPreparedStatement.java:169) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:55) at com.sun.proxy.$Proxy25.execute(Unknown Source) at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:41) at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:66) at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:45) at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:100) at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:75) at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:148) at org.apache.ibatis.session.defaults.DefaultSqlSession.insert(DefaultSqlSession.java:137) 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.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:354) ... 50 more 1. ``` 这种写法如何取到值？？

今天跑单元测试遇到一个问题。 用反射调用私有方法，私有方法里面涉及调用数据库 mapper没有注入进去的 报了空指针 类似https://www.jianshu.com/p/4b3f55e76637 这个文章的情况 但是我对他解释的原因不是很认同 因为把private改为public后 就没有报空指针 个人猜测是因为Spring 无法得知私有方法的细节，也就无法注入，请大佬讲一下深入一点的原理 ，或者源码 代码类似于 ``` Class AImpl{ @Autowried private Amapper amapper priavte void f(){ amapper.select(); } } Class Test{ @Autowried private AImpl aImpl; public void test(){ Method method = AImpl.class.getDeclaredMethod("f",null); method.setAccessible(true); method.invoke(aImpl,null); } } ```

用过JDK动态代理的人都熟悉下面的代码： interface Subject{void doSomething();} class RealSubject implements Subjuect{ public int var = 10; public void doSomething(){System.out.println("RealSubject.doSomething");} } public class SubjectProxyHandler implements InvocationHandler{ private Object proxiedObject; public Object createProxy(Object target) { //该函数传入被代理对象,返回代理对象 this.proxiedObject = target; return Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), this); } public Object invoke(Object proxy, Method method, Object[] args) { //直接调用被对象对象的方法，下面两行随便哪个都能正常执行 return method.invoke(proxiedObject, args); return method.invoke(getJdkDynamicProxiedObject(proxy),args)) result= System.out.println("事物结束"); return result; } //下面的函数传入代理对象，返回被代理对象 private static Object getJdkDynamicProxiedObject(Object proxy) { Field h = proxy.getClass().getSuperclass().getDeclaredField("h"); h.setAccessible(true); AopProxy aopProxy = (AopProxy) h.get(proxy); Field advised = aopProxy.getClass().getDeclaredField("advised"); advised.setAccessible(true); Object target = ((AdvisedSupport)advised.get(aopProxy)).getTargetSource().getTarget(); return target; } } 以上忽略了main函数创建实际对象、代理对象等过程，以上代码没有问题能够正常执行，问题是： 1）Proxy.newProxyInstance传入被代理对象（即实际对象）的类、接口和InvocationHandler的实现，返回代理对象，但是却不需要传入被代理对象本身，也就是说创建代理对象的时候不需要被代理对象本身的，各位猜猜看代理对象的var的值是多少呢？ 2）接着上面问题，建代理对象的时候不需要被代理对象本身的，但是getJdkDynamicProxiedObject却能够传入代理对象，返回被代理对象，这是如何做到的呢？ 我就不悬赏了，因为我身边JAVA做了快十年的这帮人竟然都说不清，爱好技术的大牛们，挑战本身就是悬赏了

com/sinosoft/mall/freightTransport/ui/action/FreightTransportAction$1at com.sinosoft.mall.freightTransport.ui.action.FreightTransportAction.sortByName(FreightTransportAction.java:932)at com.sinosoft.mall.freightTransport.ui.action.FreightTransportAction.getParameter(FreightTransportAction.java:1048)at com.sinosoft.mall.freightTransport.ui.action.FreightTransportAction.paySend1(FreightTransportAction.java:836)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)at java.lang.reflect.Method.invoke(Method.java:597)at com.sinosoft.sysframework.web.control.BaseProcessAction.execute(BaseProcessAction.java:60)at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:305)at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:191)at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:301)at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)at com.sinosoft.admin.common.systemconfig.SessionFilter.doFilter(SessionFilter.java:64)at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)at com.sinosoft.admin.common.systemconfig.LanguageFilter.doFilter(LanguageFilter.java:53)at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.wrapRun(WebAppServletContext.java:3730)at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3696)at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:120)at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2273)at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2179)at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1490)at weblogic.work.ExecuteThread.execute(ExecuteThread.java:256)at weblogic.work.ExecuteThread.run(ExecuteThread.java:221)11111111

package com.charming.sensor; import android.app.Activity; import android.content.Context; import android.graphics.Color; import android.hardware.Sensor; import android.hardware.SensorEvent; import android.hardware.SensorEventListener; import android.hardware.SensorManager; import android.os.Bundle; import android.view.View; import android.widget.TextView; public class MainActivity extends Activity implements SensorEventListener { private TextView valueView; private View top, left, right, bottom; private SensorManager sensorManager; private Sensor accelerometer; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); init(); } private void init() { valueView = (TextView) findViewById(R.id.values); top = findViewById(R.id.top); bottom = findViewById(R.id.bottom); left = findViewById(R.id.left); right = findViewById(R.id.right); sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE); accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER); } @Override protected void onResume() { super.onResume(); sensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_UI); } @Override protected void onPause() { super.onPause(); sensorManager.unregisterListener(this); } @Override public void onSensorChanged(SensorEvent event) { float[] values = event.values; float x = values[0] / 10; float y = values[1] / 10; int scaleFactor; if (x > 0) { scaleFactor = (int) Math.min(x * 255, 255); right.setBackgroundColor(Color.argb(scaleFactor, 255, 0, 0)); left.setBackgroundColor(Color.TRANSPARENT); } else { scaleFactor = (int) Math.min(x * 255, 255); left.setBackgroundColor(Color.argb(scaleFactor, 255, 0, 0)); right.setBackgroundColor(Color.TRANSPARENT); } if (y > 0) { scaleFactor = (int) Math.min(x * 255, 255); top.setBackgroundColor(Color.argb(scaleFactor, 255, 0, 0)); bottom.setBackgroundColor(Color.TRANSPARENT); } else { scaleFactor = (int) Math.min(x * 255, 255); bottom.setBackgroundColor(Color.argb(scaleFactor, 255, 0, 0)); top.setBackgroundColor(Color.TRANSPARENT); } valueView.setText("x:" + x + " " + "y:" + y); } @Override public void onAccuracyChanged(Sensor sensor, int accuracy) { } } 布局文件 <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.charming.sensor.MainActivity"> <TableLayout android:layout_width="match_parent" android:layout_height="match_parent" android:stretchColumns="0, 1, 2"> <TableRow android:layout_weight="1"> <view android:id="@+id/top" android:layout_column="1" /> </TableRow> <TableRow android:layout_weight="1"> <view android:id="@+id/left" android:layout_column="0" /> <view android:id="@+id/right" android:layout_column="2" /> </TableRow> <TableRow android:layout_weight="1"> <view android:id="@+id/bottom" android:layout_column="1" /> </TableRow> </TableLayout> <TextView android:id="@+id/values" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true" /> </RelativeLayout> log E/AndroidRuntime: FATAL EXCEPTION: main Process: com.charming.myapplication, PID: 7837 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.charming.myapplication/com.charming.myapplication.MainActivity}: android.view.InflateException: Binary XML file line #16: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: android.view.InflateException: Binary XML file line #16: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference at android.view.LayoutInflater.inflate(LayoutInflater.java:539) at android.view.LayoutInflater.inflate(LayoutInflater.java:423) at android.view.LayoutInflater.inflate(LayoutInflater.java:374) at com.android.internal.policy.PhoneWindow.setContentView(PhoneWindow.java:393) at android.app.Activity.setContentView(Activity.java:2166) at com.charming.myapplication.MainActivity.onCreate(MainActivity.java:24) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  at android.app.ActivityThread.-wrap11(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:148)  at android.app.ActivityThread.main(ActivityThread.java:5417)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:738) at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704) at android.view.LayoutInflater.rInflate(LayoutInflater.java:835) at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798) at android.view.LayoutInflater.rInflate(LayoutInflater.java:838) at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798) at android.view.LayoutInflater.rInflate(LayoutInflater.java:838) at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798) at android.view.LayoutInflater.inflate(LayoutInflater.java:515) at android.view.LayoutInflater.inflate(LayoutInflater.java:423)  at android.view.LayoutInflater.inflate(LayoutInflater.java:374)  at com.android.internal.policy.PhoneWindow.setContentView(PhoneWindow.java:393)  at android.app.Activity.setContentView(Activity.java:2166)  at com.charming.myapplication.MainActivity.onCreate(MainActivity.java:24)  at android.app.Activity.performCreate(Activity.java:6237)  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  at android.app.ActivityThread.-wrap11(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:148)  at android.app.ActivityThread.main(ActivityThread.java:5417)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

做项目在做一个用户首次登陆输入手机号码，发送随机密码的功能模块，首次点击完全没问题，系统会发送短信（中国移动的短信机的原理是连接它的数据库，插入一条数据即可）问题就出在连接数据库的问题上，再次发送，则后台报错ResultSet is from UPDATE. No Data.。 报错信息如下 ``` 严重: Exception occurred during processing request: ResultSet is from UPDATE. No Data. java.sql.SQLException: ResultSet is from UPDATE. No Data. at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:982) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:927) at com.mysql.jdbc.ResultSetImpl.next(ResultSetImpl.java:7152) at com.mysql.jdbc.ConnectionImpl.loadServerVariables(ConnectionImpl.java:3867) at com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3404) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2385) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2154) at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:792) at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at com.mysql.jdbc.Util.handleNewInstance(Util.java:411) at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305) at java.sql.DriverManager.getConnection(DriverManager.java:582) at java.sql.DriverManager.getConnection(DriverManager.java:185) at DAO.dbconnection2.<init>(dbconnection2.java:16) at action.testsendaction.execute(testsendaction.java:38) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) ``` dbconnection2.java 是创建连接，代码如下： ``` package DAO; import java.sql.Connection; import java.sql.DriverManager; public class dbconnection2 { private static final String DRIVER = "com.mysql.jdbc.Driver"; private static final String URL = "jdbc:mysql://*******:3306/mas?useUnicode=true&characterEncoding=gb2312"; private static final String USER = "ywz"; private static final String PASSWORD = "yw690"; private Connection con; public dbconnection2() throws Exception{ Class.forName(DRIVER); this.con = DriverManager.getConnection(URL, USER, PASSWORD); } public Connection getConnection() { return this.con; } public void closecon() throws Exception { if(this.con != null) { try { this.con.close(); } catch(Exception e) { throw e; } } } } ``` action代码： ``` public class testsendaction extends ActionSupport{ private String list; public String getList() { return list; } public void setList(String list) { this.list = list; } public String getContent() { return content; } public void setContent(String content) { this.content = content; } private String content; public String execute() throws Exception{ dbconnection2 dbc2 = new dbconnection2(); Statement s1 = dbc2.getConnection().createStatement(); Random ran = new Random(); String pwd = ""; for(int i=0;i<6;i++) { pwd += ran.nextInt(10)+""; } System.out.println("ranpwd="+pwd); String mess = "本信息来自工资查询系统，用于用户的首次登陆，登陆密码为："+pwd+" ,登陆成功后，请自行修改密码。"; String send = "insert into api_mt_6(mobiles,content) values('"+list+"','"+mess+"')"; s1.executeUpdate(send); System.out.println("send:"+send); s1.close(); dbc2.closecon(); return SUCCESS; } } ``` 报错是在数据库连接的new语句上。 连接最后也有关闭。但是就是不能进行二次访问数据库。只能重启下tomcat，然后又可以登录一次，第二次也无法连接了。 找了好久都没发现原因，希望大家帮帮忙 ，谢谢了！

想找一个简单的orm框架，写点小东西，hb 和ib 感觉有点大，不值当，于是选了 感觉挺好的，可是我将 官方的例子导入运行 却报错了，不知道什么愿意，求大神！坐等... Exception in thread "main" org.javalite.activejdbc.DBException: failed to determine Model class name, are you sure models have been instrumented? at org.javalite.activejdbc.Model$ClassGetter.getClassName(Model.java:2357) at org.javalite.activejdbc.Model.getClassName(Model.java:2330) at org.javalite.activejdbc.Model.getDaClass(Model.java:2322) at org.javalite.activejdbc.Model.getMetaModel(Model.java:60) at org.javalite.activejdbc.Model.getMetaModelLocal(Model.java:974) at org.javalite.activejdbc.Model.set(Model.java:211) at Main.main(Main.java:11) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134) Caused by: org.javalite.activejdbc.InitException: failed to determine Model class name, are you sure models have been instrumented?

最近在做一个spring security的项目,遇到了一个@PreAuthorize 问题。 在interface里面我用@PreAuthorize标记了一些method, public interface PoiActionInterface { @PreAuthorize("hasRole('ROLE_ADMIN')") public String editPoi(); @PreAuthorize("hasAnyRole('ROLE_ADMIN', 'ROLE_USER')") public String listPois(); @PreAuthorize("hasRole('ROLE_ADMIN')") public String generatePoi() throws IOException, TemplateException; @PreAuthorize("hasRole('ROLE_ADMIN')") public String deletePoi(); @PreAuthorize("hasRole('ROLE_USER')") public String trc(); } 在web server启动之后，如果权限不对，会提示exception message: access denied. 但是如果权限对了时候，会出现一些奇怪的问题， public class POIAction extends ActionSupport implements PoiActionInterface { private static final long serialVersionUID = "$Id: POIAction.java 42163 2011-08-16 18:39:30Z shany@telenav.com $".hashCode(); @Autowired private TrcHibernateService trcHibernateService; @Autowired private MailService mailService; @Autowired private TemplateService templateService; private UserGeneratedPoi userPoi; private UserGeneratedPoiDetail userPoiDetail; private String timeStart; private String timeEnd; private Integer action; private String poiid; private List<UserGeneratedPoi> userPois; private static String userFirstName; public void setUserFirstName(String userFirstName) { POIAction.userFirstName = userFirstName; } public String getUserFirstName() { return userFirstName; } public void setUserPoi(UserGeneratedPoi userPoi) { this.userPoi = userPoi; } public UserGeneratedPoi getUserPoi() { return userPoi; } public String getPoiid() { return poiid; } public void setPoiid(String poiid) { this.poiid = poiid; } public void setTimeStart(String timeStart) { this.timeStart = timeStart; } public String getTimeStart() { return timeStart; } public void setTimeEnd(String timeEnd) { this.timeEnd = timeEnd; } public String getTimeEnd() { return timeEnd; } public void setUserPoiDetail(UserGeneratedPoiDetail userPoiDetail) { this.userPoiDetail = userPoiDetail; } public UserGeneratedPoiDetail getUserPoiDetail() { return userPoiDetail; } public void setAction(Integer action) { this.action = action; } public Integer getAction() { return action; } public void setUserPois(List<UserGeneratedPoi> userPois) { this.userPois = userPois; } public List<UserGeneratedPoi> getUserPois() { return userPois; } public void getFirstName() { Object obj = SecurityContextHolder.getContext().getAuthentication().getPrincipal(); POIAction.userFirstName = ((TrcUserDetail) obj).getFirstName(); } @SkipValidation @Action(value = "trc", results = { @Result(name = "success", location = "page.addpoi", type = "tiles") }) public String trc() { return SUCCESS; } @SkipValidation @Action(value = "editpoi", results = { @Result(name = "success", location = "page.editpoi", type = "tiles") }) public String editPoi() { this.userPoi = trcHibernateService.getById(UserGeneratedPoi.class, Integer.valueOf(poiid)); this.userPoiDetail = trcHibernateService.getById(UserGeneratedPoiDetail.class, Integer.valueOf(poiid)); if (userPoiDetail.getBusinessHour() != null && userPoiDetail.getBusinessHour().split(" ").length > 0) { setTimeStart(userPoiDetail.getBusinessHour().split(" ")[0]); setTimeEnd(userPoiDetail.getBusinessHour().split(" ")[1]); } return SUCCESS; } @SkipValidation @Action(value = "deletepoi", results = { @Result(name = "success", location = "page.listpois", type = "tiles") }) public String deletePoi() { this.userPoi = trcHibernateService.getById(UserGeneratedPoi.class, Integer.valueOf(poiid)); this.userPoiDetail = trcHibernateService.getById(UserGeneratedPoiDetail.class, Integer.valueOf(poiid)); trcHibernateService.delete(this.userPoiDetail); trcHibernateService.delete(this.userPoi); this.userPois = trcHibernateService.getAll(UserGeneratedPoi.class); return SUCCESS; } @SkipValidation @Action(value = "listpois", results = { @Result(name = "success", location = "page.listpois", type = "tiles") }) public String listPois() { getFirstName(); this.userPois = trcHibernateService.getAll(UserGeneratedPoi.class); return SUCCESS; } @Validations(requiredStrings = { @RequiredStringValidator(type = ValidatorType.FIELD, fieldName = "userPoi.brandName", message = "You must enter a brand name for POIs."), @RequiredStringValidator(type = ValidatorType.FIELD, fieldName = "userPoi.street1", message = "You must enter a street address for POIs."), @RequiredStringValidator(type = ValidatorType.FIELD, fieldName = "userPoi.city", message = "You must enter a city name for POIs."), @RequiredStringValidator(type = ValidatorType.FIELD, fieldName = "userPoi.state", message = "You must enter a state name for POIs."), @RequiredStringValidator(type = ValidatorType.FIELD, fieldName = "userPoi.zip", message = "You must enter a zip code for POIs.") }, stringLengthFields = { @StringLengthFieldValidator(type = ValidatorType.FIELD, trim = true, minLength = "1", maxLength = "20", fieldName = "userPoi.street1", message = "Street 1 only can have at most 20 characters") }) @Action(value = "generatepoi", results = { @Result(name = "success", location = "page.message", type = "tiles"), @Result(name = "input", location = "page.addpoi", type = "tiles") }) public String generatePoi() throws IOException, TemplateException { SecurityContext context = SecurityContextHolder.getContext(); Authentication authentication = context.getAuthentication(); User user = new User(); user.setName(authentication.getName()); user = trcHibernateService.getAll(User.class, user).get(0); userPoi.setUserByUserId(user); if (userPoi.getId() == null) { trcHibernateService.save(userPoi); } else { try { trcHibernateService.merge(userPoi); setAction(Integer.valueOf(1)); } catch (DataIntegrityViolationException dve) { addFieldError("userPoi.id", getText("dupicate poi id")); return INPUT; } } userPoiDetail.setId(userPoi.getId()); userPoiDetail.setBusinessHour(getTimeStart() + " " + getTimeEnd() + " "); if (trcHibernateService.getById(UserGeneratedPoiDetail.class, userPoi.getId()) == null) { userPoiDetail.setUserGeneratedPoi(userPoi); trcHibernateService.save(userPoiDetail); } else { try { trcHibernateService.merge(userPoiDetail); } catch (DataIntegrityViolationException dve) { addFieldError("userPoiDetail.poiId", getText("dupicate poi detail id")); return INPUT; } } if (action == null) { addActionMessage(getText("addpoi.successful", null, "")); mailService.sendMail("shany@telenav.com", "POI Added", templateService.getNewPoiNotificationText(userPoi.getId().toString())); } else { addActionMessage(getText("editpoi.successful", null, "")); } return SUCCESS; } } 所有@autowired的object全部都是null, 所以在做action的时候会有Nullpointexception出现。 Exception Stack: java.lang.NullPointerException at com.telenav.trc.action.common.POIAction.listPois(POIAction.java:172) at com.telenav.trc.action.common.POIAction$$FastClassByCGLIB$$83c14b0a.invoke(<generated>) at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:688) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150) at org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor.invoke(MethodSecurityInterceptor.java:67) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:621) at com.telenav.trc.action.common.POIAction$$EnhancerByCGLIB$$40826733.listPois(<generated>) 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 com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:452) at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:291) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:254) at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:61) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:133) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:270) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) 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:248) at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:190) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248) at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52) at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:498) at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:368) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:78) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:119) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:187) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.session.ConcurrentSessionFilter.doFilter(ConcurrentSessionFilter.java:109) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:169) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:662)

使用kinit -k -t的时候提示： [root@xyfengkong joindomain]# kinit -k -t fengkong.keytab fengkong kinit: Keytab contains no suitable keys for fengkong@JRTEST.LOCAL while getting initial credentialsgkong.jrtest.local@JRTEST.LOCAL AdminServer.log: while getting initial credentials javax.security.auth.login.LoginException: weblogic.security.spi.IdentityAssertionException: com.bea.security.utils.kerberos.KerberosException: No valid credentials provided (Mechanism level: Attempt to obtain new ACCEPT credentials failed!) at com.bea.common.security.internal.service.ChallengeIdentityAssertionServiceImpl.assertChallengeIdentity(ChallengeIdentityAssertionServiceImpl.java:128) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at com.bea.common.security.internal.utils.Delegator$ProxyInvocationHandler.invoke(Delegator.java:57) at com.sun.proxy.$Proxy18.assertChallengeIdentity(Unknown Source) at com.bea.common.security.internal.service.NegotiateIdentityAsserterServiceImpl$NegotiateHandler.assertChallengeContext(NegotiateIdentityAsserterServiceImpl.java:327) at com.bea.common.security.internal.service.NegotiateIdentityAsserterServiceImpl$NegotiateHandler.process(NegotiateIdentityAsserterServiceImpl.java:212) at com.bea.common.security.internal.service.NegotiateIdentityAsserterServiceImpl.process(NegotiateIdentityAsserterServiceImpl.java:130) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at com.bea.common.security.internal.utils.Delegator$ProxyInvocationHandler.invoke(Delegator.java:57) at com.sun.proxy.$Proxy19.process(Unknown Source) at weblogic.security.providers.authentication.NegotiateIdentityAsserterServletAuthenticationFilter.doFilter(NegotiateIdentityAsserterServletAuthenticationFilter.java:33) at weblogic.servlet.security.internal.AuthFilterChain.doFilter(AuthFilterChain.java:34) at weblogic.servlet.security.internal.WebAppSecurity$ServletAuthenticationFilterAction.run(WebAppSecurity.java:887) at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321) at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:120) at weblogic.servlet.provider.WlsSubjectHandle.run(WlsSubjectHandle.java:57) at weblogic.servlet.security.internal.WebAppSecurity.invokeAuthFilterChain(WebAppSecurity.java:828) at weblogic.servlet.security.internal.CertSecurityModule.checkUserPerm(CertSecurityModule.java:87) at weblogic.servlet.security.internal.SecurityModule.checkAccess(SecurityModule.java:95) at weblogic.servlet.security.internal.SecurityModule.isAuthorized(SecurityModule.java:543) at weblogic.servlet.security.internal.WebAppSecurity.checkAccess(WebAppSecurity.java:499) at weblogic.servlet.security.internal.WebAppSecurity.checkAccess(WebAppSecurity.java:463) at weblogic.servlet.internal.WebAppServletContext.doSecuredExecute(WebAppServletContext.java:2119) at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2089) at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2074) at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1513) at weblogic.servlet.provider.ContainerSupportProviderImpl$WlsRequestExecutor.run(ContainerSupportProviderImpl.java:254) at weblogic.work.ExecuteThread.execute(ExecuteThread.java:256) at weblogic.work.ExecuteThread.run(ExecuteThread.java:221)

flink中如何对于所有的数据进行基于主键的去重。目前采用的keyBy(pk)后通过状态过滤，实际运行的时候checkpoints时间太长，非常阻塞性能。有没有什么更好的处理方式。另外flink-sql中的distinct具体实现逻辑是什么样子，必须指定窗口么。

今天看了ClassLoader基本原理，想自定义个ClassLoader加载类，对任何路径的class类都实用，代码如下： package test; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import org.apache.commons.io.FileUtils; public class MyClassLoader extends ClassLoader { @Override protected Class<?> findClass(String name) throws ClassNotFoundException { String path = null; String[] names = null; try { path = super.getSystemResource("").getPath(); names = name.split("/"); FileUtils.copyFile(new File(name), new File(path+"/"+(getPkgname()+"\\.").replaceAll("\\.", "/")+names[names.length-1])); } catch (IOException e) { e.printStackTrace(); } String classname = getPkgname()+"."+names[names.length-1].split("\\.")[0]; return super.getSystemClassLoader().loadClass(classname); } private String pkgname; public String getPkgname() { return pkgname; } public void setPkgname(String pkgname) { this.pkgname = pkgname; } } ``` public static void main(String[] args) throws SQLException { try { MyClassLoader my = new MyClassLoader(); my.setPkgname("test"); Class c = my.findClass("D:/Test2.class"); Object o = c.newInstance(); Method[] methods = c.getDeclaredMethods(); for (int i = 0; i < methods.length; i++) { System.out.println(methods[i].getName()); methods[i].invoke(o, null); } } catch (Exception e) { e.printStackTrace(); } ``` package test; public class Test2 { public void printa(){ System.out.println("xixi"); } } 以上分别为自定义类，测试运行类和被加载类。 代码很简单，现在问题是类似这种加载classpath外的绝对路径的类java本身的ClassLoader没有这样的方法吗？然后我这样自定义的Classloader怎么在加载时启动？不可能想上面这样直接调用加载器的方法吧，求csdn大神指点！

环境：spring+tomcat+atomikos.看错误信息和jta超时时间有关，但是我已经配置超时时间比较大了，还是不能解决这个问题:我的配置是com.tomikos.icatch.default_jta_timeout=200000，错误信息如下： ERROR org.springframework.scheduling.support.TaskUtils$LoggingErrorHandler - Unexpected error occurred in scheduled task. org.springframework.transaction.UnexpectedRollbackException: JTA transaction unexpectedly rolled back (maybe due to a timeout); nested exception is javax.transaction.RollbackException: Rolled back already.[2016-07-07 11:00:17,262][pool-1-thread-1] ERROR org.springframework.scheduling.support.TaskUtils$LoggingErrorHandler - Unexpected error occurred in scheduled task. org.springframework.transaction.UnexpectedRollbackException: JTA transaction unexpectedly rolled back (maybe due to a timeout); nested exception is javax.transaction.RollbackException: Rolled back already. at org.springframework.transaction.jta.JtaTransactionManager.doCommit(JtaTransactionManager.java:1024) at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:757) at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:726) at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:521) at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:291) 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.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653) at com.jinr.useryield.service.impl.DayYieldMessageServiceImpl$$EnhancerBySpringCGLIB$$7cbcfd50.findAll(<generated>) at com.jinr.useryield.scheduler.DayYieldMessageProduceJob.run(DayYieldMessageProduceJob.java:57) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:65) at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:81) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask.run(FutureTask.java:262) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:178) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:292) 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) Caused by: javax.transaction.RollbackException: Rolled back already. at com.atomikos.icatch.jta.TransactionImp.rethrowAsJtaRollbackException(TransactionImp.java:48) at com.atomikos.icatch.jta.TransactionImp.commit(TransactionImp.java:188) at com.atomikos.icatch.jta.TransactionManagerImp.commit(TransactionManagerImp.java:414) at com.atomikos.icatch.jta.UserTransactionImp.commit(UserTransactionImp.java:86) at org.springframework.transaction.jta.JtaTransactionManager.doCommit(JtaTransactionManager.java:1021) ... 25 more

springMvc的学习，在导入hibernate 的效验框架validation需要的jar包 就会出现的500报错 把三个包删掉就运行正常 <br/> <br/> 以下是报错信息 ``` javax.servlet.ServletException: Servlet.init() for servlet [springmvc] threw exception org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:475) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:625) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:498) org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:796) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1372) org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Thread.java:745) ``` ``` org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.validation.beanvalidation.OptionalValidatorFactoryBean#0': Lookup method resolution failed; nested exception is java.lang.IllegalStateException: Failed to introspect Class [org.springframework.validation.beanvalidation.OptionalValidatorFactoryBean] from ClassLoader [ParallelWebappClassLoader context: SpringMvc01 delegate: false ----------> Parent Classloader: java.net.URLClassLoader@5a07e868 ] org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.determineCandidateConstructors(AutowiredAnnotationBeanPostProcessor.java:265) org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineConstructorsFromBeanPostProcessors(AbstractAutowireCapableBeanFactory.java:1236) org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1151) org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:538) org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:498) org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:846) org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:863) org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546) org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:701) org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:667) org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:715) org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:590) org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:529) org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:169) javax.servlet.GenericServlet.init(GenericServlet.java:158) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:475) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:625) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:498) org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:796) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1372) org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Thread.java:745) ```

1、 # main(1) SIGSEGV(SEGV_MAPERR) 解析原始 1 #00 pc 00002d28 /system/lib/libPowerStretch.so (LucidConfig::calcTargetFPS(int)+27) [armeabi-v7a] 2 #01 pc 41863584 <unknown> 3 java: 4 com.google.android.gles_jni.EGLImpl.eglReleaseThread(Native Method) 5 android.view.HardwareRenderer$Gl20Renderer$Gl20RendererEglContext.onTerminate(HardwareRenderer.java:1743) 6 android.opengl.ManagedEGLContext.execTerminate(ManagedEGLContext.java:84) 7 android.opengl.ManagedEGLContext.doTerminate(ManagedEGLContext.java:132) 8 android.view.WindowManagerGlobal.endTrimMemory(WindowManagerGlobal.java:460) 9 android.app.ActivityThread.handleTrimMemory(ActivityThread.java:4374) 10 android.app.ActivityThread$H.handleMessage(ActivityThread.java:1531) 11 android.os.Handler.dispatchMessage(Handler.java:99) 12 android.os.Looper.loop(Looper.java:137) 13 android.app.ActivityThread.main(ActivityThread.java:5450) 14 java.lang.reflect.Method.invokeNative(Native Method) 15 java.lang.reflect.Method.invoke(Method.java:525) 16 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1187) 17 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003) 18 dalvik.system.NativeStart.main(Native Method) 2、 # main(1) SIGSEGV(SEGV_MAPERR) 解析原始 1 #00 pc 0002975c /system/lib/libdvm.so (javaLangString_length(unsigned int, unsigned int, unsigned int, unsigned int, JValue*)+12) [armeabi-v7a] 2 #01 pc 000228a4 /system/lib/libdvm.so [armeabi-v7a] 3 #02 pc 6d5a02f4 <unknown> 4 java: 5 java.lang.AbstractStringBuilder.append0(AbstractStringBuilder.java:142) 6 java.lang.StringBuilder.append(StringBuilder.java:216) 7 android.net.NetworkInfo.toString(NetworkInfo.java:444) 8 java.lang.StringBuilder.append(StringBuilder.java:202) 9 com.igexin.push.core.n.a(Unknown Source) 10 com.igexin.push.core.n.onReceive(Unknown Source) 11 android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:794) 12 android.os.Handler.handleCallback(Handler.java:733) 13 android.os.Handler.dispatchMessage(Handler.java:95) 14 android.os.Looper.loop(Looper.java:136) 15 android.app.ActivityThread.main(ActivityThread.java:5314) 16 java.lang.reflect.Method.invokeNative(Native Method) 17 java.lang.reflect.Method.invoke(Method.java:515) 18 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:864) 19 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:680) 20 dalvik.system.NativeStart.main(Native Method)

验证码是通过struts2的Action来生成的， 一旦通过DWR 框架，那么dwr2.0中 好像还是不太支持struts2， 请问该如何处理呢？ 才能在userService.checkLogin(User user,String verifyCode) 中获取到验证码？ 我的dwr配置是通过Spring的注入bean来设置的 <dwr> <allow> <convert converter="bean" match="com.squall.oa.model.User" javascript="myUser"/> <create creator="spring" javascript="userService"> <param name="beanName" value="userService"/> <include method="checkLogin"/> </create> </allow> </dwr> [b]问题补充：[/b] TO:lovewhzlq (资深架构师) 感谢您的答复！！ 那么在dwr中 为什么必须要通过 org.directwebremoting.WebContextFactory.get().getHttpServletRequest().getSession(); 去获得Session呢？ 能告诉下小弟原理是为什么吗？ [b]问题补充：[/b] 问题还是没解决 在UserService层中 调用 org.directwebremoting.WebContextFactory.get().getHttpServletRequest().getSession(); 出错 java.lang.NullPointerException at com.squall.oa.service.impl.UserServiceImpl.checkLogin(UserServiceImpl.java:84) 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:307) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204) at $Proxy11.checkLogin(Unknown Source) at com.squall.oa.action.UserAction.checkLogin(UserAction.java:41) at com.squall.oa.action.UserAction.execute(UserAction.java:34) 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 com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:404) at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:267) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:229) at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:221) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:224) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:223) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) [b]问题补充：[/b] 谢谢，可是问题还是没解决，仍然报错~ 我郁闷死了，难道s2sh 这样的架构，整合dwr这么费劲么？ [b]问题补充：[/b] TO:jansel (高级程序员) 我在测试struts2整合dwr2.0框架、 郁闷了半天，都看遍了，还是报告 'DWRActionUtil' 未定义 我都看了~~ 网站目录下也有 DWRActionUtil.js [b]问题补充：[/b] TO:jansel (高级程序员) 我已经整合成功了！ 但是 现在就差传参数了！~~ 我前台js是这么写的， 你看行么？ var username,password,result; username = $("uname").value; password = $("upass").value; var myUser = {}; myUser.u_name = username; myUser.u_pass = password; DWRActionUtil.execute({ namespace:'/user', action:'checkLogin', executeResult:'false', params:myUser }, 'frmLogin', callBackLogin);//frmDwr为表单id [b]问题补充：[/b] 那您觉得 现在如何设计登录口比较合理？ 最主要的是安全、稳定！

JAVA的反射机制。 最近看了一下一些发行的库，比如objot等是说运行是没有反射。实现了ioc与aop，不再有反射。是什么原理哦？比如我要动态地调用某个类的某个方法，就只有方法名与类名，参数列表类型，不使用反射能完成吗？ 关于反射，我真被搞晕了，什么时候才算是反射呢？ 比如 Class A { int field; void method(); } 在操作A类时。 A a = new A(); //或者这里发生反射了吗？ Class<?> c = a.getClass(); Class<?> c = A.class; //这里发生反射的操作了吗？ Method m = c.getDeclaredMethod("method",new Class[]{}); //这里应该发生了反射吧？ m.invoke(a); //这里还算是反射吗？ 我有一个Method对象时，调用method的invoke方法还算是反射吗？ 能详细说说这个吗？我老觉得我一用反射来做东西，就联想到它的性能比较差。想找代替品，又找不到更灵活的。唉。。

class FRealDataCallBack implements HCNetSDK.FRealDataCallBack_V30 { //预览回调 public void invoke(NativeLong lRealHandle, int dwDataType, ByteByReference pBuffer, int dwBufSize, Pointer pUser) { HWND hwnd =hwand; switch (dwDataType) { case HCNetSDK.NET_DVR_SYSHEAD: //系统头 if (!playControl.PlayM4_GetPort(m_lPort)) //获取播放库未使用的通道号 { break; } if (dwBufSize > 0) { if (!playControl.PlayM4_SetStreamOpenMode(m_lPort.getValue(), PlayCtrl.STREAME_REALTIME)) //设置实时流播放模式 { break; } if (!playControl.PlayM4_OpenStream(m_lPort.getValue(), pBuffer, dwBufSize, 1024 * 1024)) //打开流接口 { break; } if (!playControl.PlayM4_Play(m_lPort.getValue(), hwnd)) //播放开始 { break; } } case HCNetSDK.NET_DVR_STREAMDATA: //码流数据 if ((dwBufSize > 0) && (m_lPort.getValue().intValue() != -1)) { if (!playControl.PlayM4_InputData(m_lPort.getValue(), pBuffer, dwBufSize)) //输入流数据 { break; } } } } 回调函数里的pBuffer是否就是流数据，对于实时预览要如何处理流数据的转发

``` hibernate一个类和两个类有关联关系，但是第二个类的数组实例化是，我的代码如下 ------------------------------------------------------------------ @Entity @Table(name="user") public class User { @Id @GenericGenerator(name="uid",strategy="increment") @GeneratedValue(generator="uid") private Integer id; private String number; private String name; private String password; @OneToMany @JoinColumn(name="uid") @Cascade(org.hibernate.annotations.CascadeType.ALL) private List<Scart> scart=new ArrayList<Scart>(); @OneToMany @JoinColumn(name="uuid") @Cascade(org.hibernate.annotations.CascadeType.ALL) private List<Order> order=new ArrayList<Order>(); public List<Order> getOrder() { return order; } public void setOrder(List<Order> order) { this.order = order; } public User(String number, String name, String password) { super(); this.number = number; this.name = name; this.password = password; } public User() { // TODO Auto-generated constructor stub } public List<Scart> getScart() { return scart; } public void setScart(List<Scart> scart) { this.scart = scart; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getNumber() { return number; } public void setNumber(String number) { this.number = number; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } } ---------------------------------------------------------- @Entity @Table(name="order") public class Order { @Id @GenericGenerator(name="sid",strategy="increment") @GeneratedValue(generator="sid") private Integer id; private String name; private String url; private String number; private String price; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getUrl() { return url; } public void setUrl(String url) { this.url = url; } public String getNumber() { return number; } public void setNumber(String number) { this.number = number; } public String getPrice() { return price; } public void setPrice(String price) { this.price = price; } } ------------------------------------------------------------------------------------- @Entity @Table(name="scart") public class Scart { @Id @GenericGenerator(name="sid",strategy="increment") @GeneratedValue(generator="sid") private Integer id; private String name; private String url; private String price; private String number; public String getNumber() { return number; } public void setNumber(String number) { this.number = number; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getUrl() { return url; } public void setUrl(String url) { this.url = url; } public String getPrice() { return price; } public void setPrice(String price) { this.price = price; } } -------------------------------------------------------------- public class Test2 { @Test public void test(){ org.hibernate.Session session=HibernateUtil.openSession(); Transaction tx=session.beginTransaction(); String hql="from User u where u.number='20177720378'"; Query query=session.createQuery(hql); User user=(User) query.list().get(0); Scart scart=new Scart(); scart.setName("计算机组成原理第二版"); user.getScart().add(scart); tx.begin(); session.save(user); tx.commit(); } @Test public void test2(){ Session session=HibernateUtil.openSession(); Transaction tx=session.beginTransaction(); String hql="from User u where u.number='20177720378'"; Query query=session.createQuery(hql); User user=(User) query.list().get(0); System.out.println(user.getName()); Order order=new Order(); order.setName("计算机"); user.getOrder().add(order); tx.begin(); session.save(user); tx.commit(); } } -------------------------------------------------------------- 运行结果就是第一个测试成功，第二个测试失败了 运行结果如下 Hibernate: select user0_.id as id0_, user0_.name as name0_, user0_.number as number0_, user0_.password as password0_ from user user0_ where user0_.number='20177720378' 周小坡 Hibernate: select order0_.uuid as uuid0_1_, --------------------------------------------------------------------- 报错信息如下 org.hibernate.exception.SQLGrammarException: could not initialize a collection: [users.User.order#1] at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:92) at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) at org.hibernate.loader.Loader.loadCollection(Loader.java:2173) at org.hibernate.loader.collection.CollectionLoader.initialize(CollectionLoader.java:62) at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:627) at org.hibernate.event.def.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:83) at org.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:1863) at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:369) at org.hibernate.collection.AbstractPersistentCollection.write(AbstractPersistentCollection.java:208) at org.hibernate.collection.PersistentBag.add(PersistentBag.java:297) at test.Test2.test2(Test2.java:40) 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.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192) Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'order order0_ where order0_.uuid=1' at line 1 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) at com.mysql.jdbc.Util.getInstance(Util.java:408) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:944) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3978) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3914) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2530) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2683) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2495) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1903) at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2011) at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208) at org.hibernate.loader.Loader.getResultSet(Loader.java:1953) at org.hibernate.loader.Loader.doQuery(Loader.java:802) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:274) at org.hibernate.loader.Loader.loadCollection(Loader.java:2166) ... 31 more ```

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数据结构与算法思维导图

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终于懂了TCP和UDP协议区别

我们程序员应该抱着尝鲜、猎奇的心态，否则就容易固步自封，技术停滞不前。

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说实话，自己的算法，我一个不会，太难了吧

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我们都玩过Windows操作系统中的经典游戏扫雷（Minesweeper），如果把质数当作一颗雷，那么，表格中红色的数字哪些是雷（质数）？您能找出多少个呢？文中用列表的方式罗列了10000以内的自然数、质数（素数），6的倍数等，方便大家观察质数的分布规律及特性，以便对算法求解有指导意义。另外，判断质数是初学算法，理解算法重要性的一个非常好的案例。

正确选择比瞎努力更重要！