java Spring、MySQL 和 Hibernate：如果系统在 8 小时内未使用，则会出现数据库错误
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时间：2020-10-31 08:21:25 来源:igfitidea点击:
Spring, MySQL and Hibernate: Database error if the system is not used within 8 hours
提问by PartyWithJohn
I am working on a Spring, MySQL and Hibernate project and If the project is not used within 8 hours I get the following error. Can someone please tell me why. It looks like if I reboot the server everything works great until night time or if no one is using the system mid day for a few hours. can someone please help me out I just found this issue in a few of my projects so I must be making the same mistake in a number of projects.. please help
我正在处理 Spring、MySQL 和 Hibernate 项目，如果该项目在 8 小时内未使用，我会收到以下错误。有人可以告诉我为什么。看起来如果我重新启动服务器，一切都很好，直到晚上，或者如果没有人在中午使用系统几个小时。有人可以帮帮我吗我刚刚在我的一些项目中发现了这个问题，所以我一定在一些项目中犯了同样的错误..请帮忙
Here is a example of my java code am I missing something:
这是我的 Java 代码示例，我是否遗漏了什么：
public void saveVisit(VisitModel visit) throws Exception {
LOGGER.debug("[" + visit.toString() + "]");
sessionFactory.getCurrentSession().saveOrUpdate(visit);
}
@SuppressWarnings("unchecked")
public School_lookupModel getSchoolInformation(String schoolCode)
{
return (School_lookupModel) sessionFactory.getCurrentSession()
.createCriteria(School_lookupModel.class)
.add( Restrictions.like("school", schoolCode))
.uniqueResult();
}
Here is the console output of the errors:
这是错误的控制台输出：
2012-09-06 08:00:07,088 [http-8080-2] WARN org.hibernate.util.JDBCExceptionReporter - SQL Error: 0, SQLState: 08S01
2012-09-06 08:00:07,088 [http-8080-2] ERROR org.hibernate.util.JDBCExceptionReporter - Communications link failure due to underlying exception:
** BEGIN NESTED EXCEPTION **
java.io.EOFException
STACKTRACE:
java.io.EOFException
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1963)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2375)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2874)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1623)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1715)
at com.mysql.jdbc.Connection.execSQL(Connection.java:3249)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1268)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1403)
at org.apache.commons.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:93)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1849)
at org.hibernate.loader.Loader.doQuery(Loader.java:718)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270)
at org.hibernate.loader.Loader.doList(Loader.java:2294)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2172)
at org.hibernate.loader.Loader.list(Loader.java:2167)
at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:119)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1706)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:347)
at org.uftwf.schoolvisit.dao.SchoolVisitDAOImpl.getSelectableReporters(SchoolVisitDAOImpl.java:56)
at org.uftwf.schoolvisit.service.SchoolVisitServiceImpl.getSelectableReporters(SchoolVisitServiceImpl.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:616)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:318)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
at $Proxy36.getSelectableReporters(Unknown Source)
at org.uftwf.schoolvisit.controller.swf.FlowActions.initializeSelectableReports(FlowActions.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:616)
at org.springframework.expression.spel.support.ReflectiveMethodExecutor.execute(ReflectiveMethodExecutor.java:69)
at org.springframework.expression.spel.ast.MethodReference.getValueInternal(MethodReference.java:84)
at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:57)
at org.springframework.expression.spel.ast.SpelNodeImpl.getTypedValue(SpelNodeImpl.java:102)
at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:97)
at org.springframework.binding.expression.spel.SpringELExpression.getValue(SpringELExpression.java:84)
at org.springframework.webflow.action.EvaluateAction.doExecute(EvaluateAction.java:75)
at org.springframework.webflow.action.AbstractAction.execute(AbstractAction.java:188)
at org.springframework.webflow.execution.AnnotatedAction.execute(AnnotatedAction.java:145)
at org.springframework.webflow.execution.ActionExecutor.execute(ActionExecutor.java:51)
at org.springframework.webflow.engine.ActionList.execute(ActionList.java:155)
at org.springframework.webflow.engine.Flow.start(Flow.java:534)
at org.springframework.webflow.engine.impl.FlowExecutionImpl.start(FlowExecutionImpl.java:366)
at org.springframework.webflow.engine.impl.FlowExecutionImpl.start(FlowExecutionImpl.java:222)
at org.springframework.webflow.executor.FlowExecutorImpl.launchExecution(FlowExecutorImpl.java:140)
at org.springframework.webflow.mvc.servlet.FlowHandlerAdapter.handle(FlowHandlerAdapter.java:193)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:679)
** END NESTED EXCEPTION **
Last packet sent to the server was 13 ms ago.
2012-09-06 08:00:07,089 [http-8080-2] WARN org.hibernate.util.JDBCExceptionReporter - SQL Error: 0, SQLState: null
2012-09-06 08:00:07,089 [http-8080-2] ERROR org.hibernate.util.JDBCExceptionReporter - Already closed.
2012-09-06 08:00:07,089 [http-8080-2] WARN org.hibernate.util.JDBCExceptionReporter - SQL Error: 0, SQLState: null
2012-09-06 08:00:07,089 [http-8080-2] ERROR org.hibernate.util.JDBCExceptionReporter - Already closed.
Sep 6, 2012 8:00:07 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet spring threw exception
com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception:
** BEGIN NESTED EXCEPTION **
java.io.EOFException
STACKTRACE:
java.io.EOFException
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1963)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2375)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2874)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1623)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1715)
at com.mysql.jdbc.Connection.execSQL(Connection.java:3249)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1268)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1403)
at org.apache.commons.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:93)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1849)
at org.hibernate.loader.Loader.doQuery(Loader.java:718)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270)
at org.hibernate.loader.Loader.doList(Loader.java:2294)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2172)
at org.hibernate.loader.Loader.list(Loader.java:2167)
at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:119)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1706)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:347)
at org.uftwf.schoolvisit.dao.SchoolVisitDAOImpl.getSelectableReporters(SchoolVisitDAOImpl.java:56)
at org.uftwf.schoolvisit.service.SchoolVisitServiceImpl.getSelectableReporters(SchoolVisitServiceImpl.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:616)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:318)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
at $Proxy36.getSelectableReporters(Unknown Source)
at org.uftwf.schoolvisit.controller.swf.FlowActions.initializeSelectableReports(FlowActions.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:616)
at org.springframework.expression.spel.support.ReflectiveMethodExecutor.execute(ReflectiveMethodExecutor.java:69)
at org.springframework.expression.spel.ast.MethodReference.getValueInternal(MethodReference.java:84)
at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:57)
at org.springframework.expression.spel.ast.SpelNodeImpl.getTypedValue(SpelNodeImpl.java:102)
at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:97)
at org.springframework.binding.expression.spel.SpringELExpression.getValue(SpringELExpression.java:84)
at org.springframework.webflow.action.EvaluateAction.doExecute(EvaluateAction.java:75)
at org.springframework.webflow.action.AbstractAction.execute(AbstractAction.java:188)
at org.springframework.webflow.execution.AnnotatedAction.execute(AnnotatedAction.java:145)
at org.springframework.webflow.execution.ActionExecutor.execute(ActionExecutor.java:51)
at org.springframework.webflow.engine.ActionList.execute(ActionList.java:155)
at org.springframework.webflow.engine.Flow.start(Flow.java:534)
at org.springframework.webflow.engine.impl.FlowExecutionImpl.start(FlowExecutionImpl.java:366)
at org.springframework.webflow.engine.impl.FlowExecutionImpl.start(FlowExecutionImpl.java:222)
at org.springframework.webflow.executor.FlowExecutorImpl.launchExecution(FlowExecutorImpl.java:140)
at org.springframework.webflow.mvc.servlet.FlowHandlerAdapter.handle(FlowHandlerAdapter.java:193)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:679)
** END NESTED EXCEPTION **
Last packet sent to the server was 13 ms ago.
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2586)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2874)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1623)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1715)
at com.mysql.jdbc.Connection.execSQL(Connection.java:3249)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1268)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1403)
at org.apache.commons.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:93)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1849)
at org.hibernate.loader.Loader.doQuery(Loader.java:718)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270)
at org.hibernate.loader.Loader.doList(Loader.java:2294)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2172)
at org.hibernate.loader.Loader.list(Loader.java:2167)
at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:119)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1706)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:347)
at org.uftwf.schoolvisit.dao.SchoolVisitDAOImpl.getSelectableReporters(SchoolVisitDAOImpl.java:56)
at org.uftwf.schoolvisit.service.SchoolVisitServiceImpl.getSelectableReporters(SchoolVisitServiceImpl.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:616)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:318)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
at $Proxy36.getSelectableReporters(Unknown Source)
at org.uftwf.schoolvisit.controller.swf.FlowActions.initializeSelectableReports(FlowActions.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:616)
at org.springframework.expression.spel.support.ReflectiveMethodExecutor.execute(ReflectiveMethodExecutor.java:69)
at org.springframework.expression.spel.ast.MethodReference.getValueInternal(MethodReference.java:84)
at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:57)
at org.springframework.expression.spel.ast.SpelNodeImpl.getTypedValue(SpelNodeImpl.java:102)
at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:97)
at org.springframework.binding.expression.spel.SpringELExpression.getValue(SpringELExpression.java:84)
at org.springframework.webflow.action.EvaluateAction.doExecute(EvaluateAction.java:75)
at org.springframework.webflow.action.AbstractAction.execute(AbstractAction.java:188)
at org.springframework.webflow.execution.AnnotatedAction.execute(AnnotatedAction.java:145)
at org.springframework.webflow.execution.ActionExecutor.execute(ActionExecutor.java:51)
at org.springframework.webflow.engine.ActionList.execute(ActionList.java:155)
at org.springframework.webflow.engine.Flow.start(Flow.java:534)
at org.springframework.webflow.engine.impl.FlowExecutionImpl.start(FlowExecutionImpl.java:366)
at org.springframework.webflow.engine.impl.FlowExecutionImpl.start(FlowExecutionImpl.java:222)
at org.springframework.webflow.executor.FlowExecutorImpl.launchExecution(FlowExecutorImpl.java:140)
at org.springframework.webflow.mvc.servlet.FlowHandlerAdapter.handle(FlowHandlerAdapter.java:193)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:679)
回答by Nirmal- thInk beYond
Use c3p0for pool, it is used ready for production use
使用c3p0作为池，它用于生产使用
Use this parameter(you can modify to optimize), that will retain your connection active
使用此参数（您可以修改以优化），这将使您的连接保持活动状态
<property name="hibernate.c3p0.timeout">1800</property>
<property name="hibernate.c3p0.idle_test_period">100</property>
EDIT You can also increase 8 hour limit by below parameter
编辑您还可以通过以下参数增加 8 小时限制
http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html#sysvar_wait_timeout
http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html#sysvar_wait_timeout
回答by manko
This happens because mysql drops connection after 8 hours. One way to fix this is to use c3p0as mentioned in other posts. Another way is to use mysql's autoReconnect=trueproperty in the jdbc url. This property will attempt to reconnect when the next query is issued on the connection.
发生这种情况是因为 mysql 在 8 小时后断开连接。解决此问题的一种方法是使用c3p0其他帖子中提到的方法。另一种方法是autoReconnect=true在 jdbc url 中使用 mysql 的属性。当对连接发出下一个查询时，此属性将尝试重新连接。
More here: http://dev.mysql.com/doc/refman/5.0/en/connector-j-reference-configuration-properties.html
更多信息：http: //dev.mysql.com/doc/refman/5.0/en/connector-j-reference-configuration-properties.html
Note that autoReconnectwill only handle the connection part. It will not re execute the query automatically. You will have to deal with that yourself by catching SQLExceptionand retrying the query in your code. I recently ran into this and it worked for me.
注意，autoReconnect只会处理连接部分。它不会自动重新执行查询。您将不得不通过SQLException在代码中捕获并重试查询来自己处理该问题。我最近遇到了这个，它对我有用。
回答by Matei Florescu
What happens is that your app is trying to use a closed connection. This happens because Mysql is automatically closing the connection, but your app does not know that. The main problem is you're properly closing the connections you use. In Hibernate terms, this means you're not closing the Session. Check your code to make sure you're closing every connection after you use it. If you're using the Spring-Hibernate integration, then check the Spring documentation on integration.
发生的情况是您的应用程序正在尝试使用关闭的连接。发生这种情况是因为 Mysql 会自动关闭连接，但您的应用程序不知道这一点。主要问题是您正确关闭了您使用的连接。在 Hibernate 术语中，这意味着您不会关闭会话。检查您的代码以确保在使用后关闭每个连接。如果您使用的是 Spring-Hibernate 集成，请查看有关集成的 Spring 文档。
