解决com.microsoft.sqlserver.jdbc.SQLServerException: 该连接已关闭

com.microsoft.sqlserver.jdbc.SQLServerException: 该连接已关闭。
    at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:130)
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.checkClosed(SQLServerConnection.java:294)
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.prepareStatement(SQLServerConnection.java:1980)
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.prepareStatement(SQLServerConnection.java:1702)
    at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:497)
    at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:415)
    at org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:139)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1538)
    at org.hibernate.loader.Loader.doQuery(Loader.java:661)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224)
    at org.hibernate.loader.Loader.doList(Loader.java:2211)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2095)
    at org.hibernate.loader.Loader.list(Loader.java:2090)
    at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:289)
    at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1695)
    at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:142)
    at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:150)
    at com.standsoft.service.PeisPatientService.GetPatientExamDepart(PeisPatientService.java:484)
    at com.standsoft.btree.Depart.exesql(Depart.java:26)
    at com.standsoft.controller.MainController.target(MainController.java:137)
    at sun.reflect.GeneratedMethodAccessor57.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:436)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1757)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1716)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:722)

问题原因：

该异常说明程序与数据库连接断开

为了排查问题，我们做如下几个假设

1，程序bug

2，部署程序的服务器（网络或其它）问题

3，部署数据库服务器（网络或其它）问题

问题探讨

a分析程序，并无明显bug

b模拟部署服务器故障，断开网络，出现上述异常。断开本地数据库服务，出现上述异常

c模拟部署数据库的服务器故障，断开数据库服务，出现上述异常。

在经过b和c故障后，a仍不能获取连接。分析发现，session和sessionfactory不为空，因此也没走到rebuildSessionFactory重连数据库。获取session代码如下

    /**
     * Returns the ThreadLocal Session instance. Lazy initialize the
     * <code>SessionFactory</code> if needed.
     *
     * @return Session
     * @throws HibernateException
     */
    public static Session getSession() throws HibernateException {
        Session session = threadLocal.get();

        if (session == null || !session.isOpen()) {
            if (sessionFactory == null) {
                rebuildSessionFactory();
            }
            session = (sessionFactory != null) ? sessionFactory.openSession() : null;
            threadLocal.set(session);
        }

        return session;
    }

    /**
     * Rebuild hibernate session factory
     *
     */
    public static void rebuildSessionFactory() {
        System.out.println("-------------------------------rebuildSessionFactory----------------------------------");
        try {
            configuration.configure(configFile);
            sessionFactory = configuration.buildSessionFactory();
        } catch (Exception e) {
            System.err.println("%%%% Error Creating SessionFactory %%%%");
            e.printStackTrace();
        }
    }

既然数据库连接问题，给hibernate加上了连接池

hibernate配置文件部分代码如下

    <session-factory>
        <property name="dialect">com.standsoft.dialect.DialectForInkfish</property>
        <property name="connection.url">jdbc:sqlserver://localhost:1433;DatabaseName=yanan</property>
        <property name="connection.username">sa</property>
        <property name="connection.password">yanan</property>
        <property name="connection.driver_class">com.microsoft.sqlserver.jdbc.SQLServerDriver</property>
        <property name="myeclipse.connection.profile">sql2008-4</property>
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>

        <property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
        <property name="hibernate.c3p0.min_size">1</property> 

        <property name="hibernate.c3p0.max_size">200</property> 

        <!-- Seconds a Connection can remain pooled but unused before being discarded. Zero means idle connections never expire. [See "Basic Pool Configuration"] -->
        <property name="hibernate.c3p0.time_out">5</property> 

        <!-- The size of c3p0's global PreparedStatement cache. -->
        <property name="hibernate.c3p0.max_statements">200</property> 

    </session-factory>

至此，在模拟bc故障并恢复后程序也恢复了正常。

网上看到有说hibernate用不用连接池没多大区别的。你们不知道别误人子弟哈。还有说connection不能静态的，若读者按照我的方法不行，可试试这个

网上还要配置c3p0错误的，大家注意。我的是按照官网配置的

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