求hibernate事物有关问题

public class example {    public void addUser(S s) throws HibernateException {       //获得Hibernate session       Session session = HibernateSessionFactory.getSession();       Transaction tx =session.beginTransaction();       //将s对象内容保存到数据库       session.save(s);       session.flush();       tx.commit();       //关闭Hibernate session      // HibernateSessionFactory.closeSession();       //session.close();    }       public static void main(String[] msg) {       example example = new example();       S s = new S();       s.setSno(57);       s.setSname("1234");       try {           example.addUser(s);       } catch (HibernateException e) {}          }}