异常堆栈信息 

[Request processing failed; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.] with root cause java.net.SocketException: Connection timed out (Write failed)	at java.net.SocketOutputStream.socketWrite0(Native Method)	at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:111)	at java.net.SocketOutputStream.write(SocketOutputStream.java:155)	at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)	at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)	at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3731)	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2512)	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2683)	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2482)	at com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:4796)	at sun.reflect.GeneratedMethodAccessor127.invoke(Unknown Source)	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)	at java.lang.reflect.Method.invoke(Method.java:498)	at org.apache.tomcat.jdbc.pool.ProxyConnection.invoke(ProxyConnection.java:126)	at org.apache.tomcat.jdbc.pool.JdbcInterceptor.invoke(JdbcInterceptor.java:108)	at org.apache.tomcat.jdbc.pool.interceptor.AbstractCreateStatementInterceptor.invoke(AbstractCreateStatementInterceptor.java:79)	at org.apache.tomcat.jdbc.pool.JdbcInterceptor.invoke(JdbcInterceptor.java:108)	at org.apache.tomcat.jdbc.pool.DisposableConnectionFacade.invoke(DisposableConnectionFacade.java:81)	at com.sun.proxy.$Proxy83.setAutoCommit(Unknown Source)	at org.hibernate.resource.jdbc.internal.AbstractLogicalConnectionImplementor.begin(AbstractLogicalConnectionImplementor.java:67)	at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.begin(LogicalConnectionManagedImpl.java:238)	at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.begin(JdbcResourceLocalTransactionCoordinatorImpl.java:214)	at org.hibernate.engine.transaction.internal.TransactionImpl.begin(TransactionImpl.java:52)	at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1512)	at org.hibernate.jpa.internal.TransactionImpl.begin(TransactionImpl.java:45)	at org.springframework.orm.jpa.vendor.HibernateJpaDialect.beginTransaction(HibernateJpaDialect.java:189)	at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:380)	at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:377)	at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:461)	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:277)	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:671)	at com.annet.hospital.applet.service.user.PatientServiceImpl$$EnhancerBySpringCGLIB$$825266d.getRecentConsultDoctor(
    
     )	at com.annet.hospital.applet.controller.user.PatientController.recentDoctors(PatientController.java:132)	at sun.reflect.GeneratedMethodAccessor357.invoke(Unknown Source)	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)	at java.lang.reflect.Method.invoke(Method.java:498)	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)	at javax.servlet.http.HttpServlet.service(HttpServlet.java:661)	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)	at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)	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:52)	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.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)	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.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109)	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)	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.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81)	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)	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:197)	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)	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:198)	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496)	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1468)	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)
    

项目使用Springboot 1.5.13.RELEASE，默认的数据库连接池是tomcat-jdbc。

出现这种异常的原因是：

Mysql 服务器默认的“wait_timeout”是8小时，也就是说一个connection空闲超过8个小时，Mysql将自动断开该connection。 这就是问题的所在，在连接池中的connections如果空闲超过8小时，mysql将其断开，而连接池并不知道该connection已经失效，如果这时有 Client请求connection，连接池将该失效的Connection提供给Client，将会造成上面的异常。

至于出现：No operations allowed after connection closed。这样的问题原因只有一个，你这里和数据库的连接Connection是一个Static的，程序共享这一个Connection。所以第一 次对数据库操作没问题，当把Connection关闭后，第二次还想操作数据库时Connection肯定不存在了。

我的个人配置如下

#MYSQL 8小时连接超时配置#验证连接的有效性spring.datasource.test-while-idle=true#获取连接时候验证，会影响性能spring.datasource.test-on-borrow=truespring.datasource.validation-query=SELECT 1 #空闲连接回收的时间间隔，与test-while-idle一起使用，设置5分钟spring.datasource.time-between-eviction-runs-millis=300000#连接池空闲连接的有效时间 ，设置30分钟spring.datasource.min-evictable-idle-time-millis=1800000