mysql重连，连接丢失： The last packet sent successfully to the server was 36,799,662 milliseconds ago.

出错信息：

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 36,799,660 milliseconds ago.  The last packet sent successfully to the server was 36,799,662 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.
	sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
	com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121)
	com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3938)
	com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2551)
	com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2731)
	com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2809)
	com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:5333)
	org.apache.commons.dbcp.DelegatingConnection.setAutoCommit(DelegatingConnection.java:371)
	org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.setAutoCommit(PoolingDataSource.java:328)
	org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:72)
	org.hibernate.engine.transaction.spi.AbstractTransactionImpl.begin(AbstractTransactionImpl.java:160)
	org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1425)
	org.springframework.orm.hibernate4.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:502)
	org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)
	org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:427)
	org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:276)
	org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
	org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
	org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
	org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
	org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:655)
	com.star.rabbit.service.CourseService$$EnhancerBySpringCGLIB$$4c625bd9.getcoursedetial()
	com.star.rabbit.controller.CourseController.getcoursedetial(CourseController.java:92)
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	java.lang.reflect.Method.invoke(Method.java:498)
	org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:222)
	org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
	org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:814)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:737)
	org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
	org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
	org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:969)
	org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:871)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:688)
	org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:845)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	com.thetransactioncompany.cors.CORSFilter.doFilter(CORSFilter.java:168)
	com.thetransactioncompany.cors.CORSFilter.doFilter(CORSFilter.java:233)
	org.springframework.orm.hibernate4.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:151)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

问题原因，由于服务器长时间没有操作数据库，造成链接中断。
解决方式：
1.采用JDBC方式（以mysql为例）：
在JDBC URL上添加?autoReconnect=true，如：
jdbc:mysql://localhost:3306/mydb?autoReconnect=true
2.如果是在Spring中使用DBCP连接池，在定义datasource增加属性validationQuery和testOnBorrow，如：

3.如果是在Spring中使用c3p0连接池，则在定义datasource的时候，添加属性testConnectionOnCheckin和testConnectionOnCheckout，如：