org.hibernate.exception.JDBCConnectionException：无法打开连接

Question

我偶尔会发现以下异常。我不会每次都得到它，它发生在10次中有5次我请求某个页面。我使用JSF + Hibernate构建了网站，并部署在Apache Tomcat上。

org.hibernate.exception.JDBCConnectionException: Cannot open connection 
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74) 
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43) 
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29) 
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:426) 
at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:144) 
at org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:119) 
at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:57) 
at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1326) 
at com.bean.PostsBean.getCategoriesList(PostsBean.java:137) 
at sun.reflect.GeneratedMethodAccessor291.invoke(Unknown Source) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) 
at java.lang.reflect.Method.invoke(Method.java:597) 
at javax.el.BeanELResolver.invoke(BeanELResolver.java:484) 
at javax.el.CompositeELResolver.invoke(CompositeELResolver.java:161) 
at org.apache.el.parser.AstValue.getValue(AstValue.java:173) 
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:185) 
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109) 
at com.sun.faces.facelets.tag.jstl.core.ForEachHandler.apply(ForEachHandler.java:161) 
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:95) 
at com.sun.faces.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:93) 
at com.sun.faces.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:87) 
at com.sun.faces.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:312) 
at com.sun.faces.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:371) 
at com.sun.faces.facelets.impl.DefaultFacelet.include(DefaultFacelet.java:350) 
at com.sun.faces.facelets.impl.DefaultFaceletContext.includeFacelet(DefaultFaceletContext.java:199) 
at com.sun.faces.facelets.tag.ui.IncludeHandler.apply(IncludeHandler.java:120) 
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:95) 
at javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137) 
at com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:190) 
at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120) 
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:95) 
at com.sun.faces.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:93) 
at com.sun.faces.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:87) 
at com.sun.faces.facelets.impl.DefaultFacelet.apply(DefaultFacelet.java:161) 
at com.sun.faces.application.view.FaceletViewHandlingStrategy.buildView(FaceletViewHandlingStrategy.java:972) 
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:99) 
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) 
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219) 
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:203) 
at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:181) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) 
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) 
at com.googlecode.psiprobe.Tomcat70AgentValve.invoke(Tomcat70AgentValve.java:38) 
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) 
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) 
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023) 
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589) 
at org.apache.tomcat.util.net.AprEndpoint$SocketWithOptionsProcessor.run(AprEndpoint.java:1810) 
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) 
at java.lang.Thread.run(Thread.java:662) 
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure 

The last packet successfully received from the server was 291,242 milliseconds ago. The last packet sent successfully to the server was 1 milliseconds 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:411) 
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117) 
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3603) 
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3492) 
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4043) 
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2503) 
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2664) 
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2788) 
at com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:5282) 
at com.mchange.v2.c3p0.impl.NewProxyConnection.setAutoCommit(NewProxyConnection.java:881) 
at org.hibernate.connection.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:61) 
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:423) 
... 55 more 
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:3052) 
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3503) 
... 64 more 

Answer 1

根异常的消息告诉你的问题：

Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost. 

您的服务器和数据库服务器之间的网络连接不稳定。所以这不是你的软件的问题。