我构建了一个Web应用程序，并在本地完美部署。我将其部署在远程服务器上并开始获取：except

> 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来构建Web应用程序并将该Web应用程序部署在Linux服务器中。它的登录功能在一段时间内运行良好，但是登录后无法正常工作，并且在Tomcat日志文件中显示了Exception。