MySQLNonTransientConnectionException：连接关闭后不允许任何操作。连接

我构建了一个Web应用程序，并在本地部署完美。 我将它部署在远程服务器上并开始获取：exception

> javax.servlet.ServletException: could not execute query org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:518) org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:421) >root cause >org.hibernate.exception.JDBCConnectionException: could not execute query org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74) org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43) org.hibernate.loader.Loader.doList(Loader.java:2223) org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2104) org.hibernate.loader.Loader.list(Loader.java:2099) org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:94) org.hibernate.impl.SessionImpl.list(SessionImpl.java:1569) org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:283) data.dao.UserDAO.findByUsername(UserDAO.java:42) action.registration.LoginAction.execute(LoginAction.java:24) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) java.lang.reflect.Method.invoke(Method.java:597) com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:399) com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:262) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:224) com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:213) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:150) org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:48) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:123) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.ParametersInterceptor.intercept(ParametersInterceptor.java:161) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:105) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:83) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:207) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:74) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:127) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) org.apache.struts2.interceptor.ProfilingActivationInterceptor.intercept(ProfilingActivationInterceptor.java:107) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:206) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:115) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:143) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.PrepareInterceptor.intercept(PrepareInterceptor.java:115) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:170) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:123) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:50) org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:507) org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:421) >root cause >com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.Connection was implicitly closed due to underlying exception/error: ** BEGIN NESTED EXCEPTION ** >com.mysql.jdbc.exceptions.jdbc4.CommunicationsException MESSAGE: Communications link failure >Last packet sent to the server was 43 ms ago. >STACKTRACE: >com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure >Last packet sent to the server was 43 ms ago. 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:406) at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2985) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2871) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3414) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1936) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2542) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1734) at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1885) at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:186) at org.hibernate.loader.Loader.getResultSet(Loader.java:1787) at org.hibernate.loader.Loader.doQuery(Loader.java:674) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236) at org.hibernate.loader.Loader.loadEntity(Loader.java:1860) at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:48) at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:42) at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3042) at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:395) at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:375) at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:139) at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:195) at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:103) at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:878) at org.hibernate.impl.SessionImpl.get(SessionImpl.java:815) at org.hibernate.impl.SessionImpl.get(SessionImpl.java:808) at data.base._BaseRootDAO.get(_BaseRootDAO.java:228) at data.base._BaseRootDAO.get(_BaseRootDAO.java:217) at data.base.BaseUserDAO.get(BaseUserDAO.java:49) at util.UserUtil.getUser(UserUtil.java:22) at action.market.ArmsDealerAction.display(ArmsDealerAction.java:62) at action.market.ArmsDealerAction.displayUser(ArmsDealerAction.java:54) 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:399) at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:262) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:224) at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:213) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:150) at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:48) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:123) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at com.opensymphony.xwork2.interceptor.ParametersInterceptor.intercept(ParametersInterceptor.java:161) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:105) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:83) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:207) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:74) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:127) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at org.apache.struts2.interceptor.ProfilingActivationInterceptor.intercept(ProfilingActivationInterceptor.java:107) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:123) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) at com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) at com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874) at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665) at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528) at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689) at java.lang.Thread.run(Thread.java:619) Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost. at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2431) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2882) ... 141 more ** END NESTED EXCEPTION ** >sun.reflect.GeneratedConstructorAccessor72.newInstance(Unknown Source) sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) java.lang.reflect.Constructor.newInstance(Constructor.java:513) com.mysql.jdbc.Util.handleNewInstance(Util.java:406) com.mysql.jdbc.Util.getInstance(Util.java:381) com.mysql.jdbc.SQLError.createSQLException(SQLError.java:984) com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956) com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926) com.mysql.jdbc.ConnectionImpl.checkClosed(ConnectionImpl.java:1098) com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4076) com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4042) org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:505) org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:423) org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:139) org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1547) org.hibernate.loader.Loader.doQuery(Loader.java:673) org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236) org.hibernate.loader.Loader.doList(Loader.java:2220) org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2104) org.hibernate.loader.Loader.list(Loader.java:2099) org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:94) org.hibernate.impl.SessionImpl.list(SessionImpl.java:1569) org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:283) data.dao.UserDAO.findByUsername(UserDAO.java:42) action.registration.LoginAction.execute(LoginAction.java:24) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) java.lang.reflect.Method.invoke(Method.java:597) com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:399) com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:262) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:224) com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:213) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:150) org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:48) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:123) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.ParametersInterceptor.intercept(ParametersInterceptor.java:161) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:105) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:83) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:207) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:74) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:219) com.opensymphony.xwork2.DefaultActionInvocation$2.doProfiling(DefaultActionInvocation.java:218) com.opensymphony.xwork2.util.profiling.UtilTimerStack.profile(UtilTimerStack.java:455) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:216) com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:127) 

我已经使用hibernate和struts构建Web应用程序并在Linux服务器中部署Web应用程序。它的登录function运行良好一段时间，但在登录后无效并在Tomcat日志文件中显示exception。

Answer 1

根据错误堆栈跟踪，您与MySQL服务器的连接将丢失。

 >root cause >com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed. Connection was implicitly closed due to underlying exception/error: ** BEGIN NESTED EXCEPTION ** >com.mysql.jdbc.exceptions.jdbc4.CommunicationsException MESSAGE: Communications link failure >Last packet sent to the server was 43 ms ago. >STACKTRACE: >com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 

很明显，根本原因是Communications link failure 。

尝试ping您的数据库服务器，看看您是否能够连接。
否则解决网络问题然后连接。 没有替代品。

您可以对数据库服务器发出轻量级ping ，以检查连接可用性。
请阅读以下讨论和文章：

1. Ping MySQL服务器
2. Ping语法和示例