请求处理失败；嵌套异常为java.lang.IllegalStateException：Session / EntityManager已关闭

Question

我正在从JSP页面传递数据并将其保存在数据库中。所有值都已正确存储在数据库中。但是，我的控制台和UI出现错误。

堆栈跟踪：

Jun 25, 2018 8:13:02 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [dispatcher] in context with path [/IEFMSystem] threw exception [Request processing failed; nested exception is java.lang.IllegalStateException: Session/EntityManager is closed] with root cause
java.lang.IllegalStateException: Session/EntityManager is closed
    at org.hibernate.internal.AbstractSharedSessionContract.checkOpen(AbstractSharedSessionContract.java:357)
    at org.hibernate.engine.spi.SharedSessionContractImplementor.checkOpen(SharedSessionContractImplementor.java:138)
    at org.hibernate.internal.AbstractSharedSessionContract.checkOpenOrWaitingForAutoClose(AbstractSharedSessionContract.java:363)
    at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1254)
    at org.hibernate.internal.SessionImpl.access$1900(SessionImpl.java:207)

DAOImpl类中的方法-

@Override     public void addNewContributorMethod（User user）{

    userFactory = new Configuration()
            .configure("hibernate.cfg.xml")
            .addAnnotatedClass(User.class)
            .buildSessionFactory();

    Session userSession = userFactory.getCurrentSession();

    try
    {                       
        System.out.println("Inside addNewContributorMethod of DAO");
        // start a transaction
        userSession.beginTransaction();

        // save the student object
        System.out.println("Saving the student..." + " User Id: " + user.getUserId() + " User Name: " + user.getUserName());
        userSession.save(user);         
        System.out.println(user);

        // commit transaction
        try
        {
            userSession.getTransaction().commit();  
        }
        catch(Exception e)
        {
            System.out.println(e);
        }
        System.out.println(userSession.get(User.class, user.getUserId()));
        System.out.println("Done!");
    }
    finally
    {
        System.out.println("In Finally");
        //userSession.close();
        //userFactory.close();

    }
}