import  org.hibernate.*;
 import  org.hibernate.cfg.*;

 public   class  HibernateUtil {

     public   static   final  SessionFactory sessionFactory;

     static  {
         try  {
            Configuration  cfg  =  new  Configuration().addClass(UserAccount. class ).addClass(UserGroup. class ).addClass(
                    Role. class ).addClass(UserRole. class );
            sessionFactory = cfg.buildSessionFactory();
        }  catch  (Throwable ex) {
            System.err.println("Initial SessionFactory creation failed." + ex);
             throw   new  ExceptionInInitializerError(ex);
        }
    }

     public   static   final  ThreadLocal session =  new  ThreadLocal();

     public   static  Session currentSession()  throws  HibernateException {
        Session s = (Session) session.get();
        // Open a new Session, if this thread has none yet
         if  (s ==  null ) {
            s = sessionFactory.openSession();
            // Store it in the ThreadLocal variable
            session.set(s);
        }
         return  s;
    }

     public   static   void  closeSession()  throws  HibernateException {
        Session s = (Session) session.get();
         if  (s !=  null )
            s.close();
        session.set( null );
    }
}

HibernateUtil.currentSession();

HibernateUtil.closeSession();