Hibernate登录错误，求解

    @Override    public User isLogin(String username,String password) {        User user=null;        session.beginTransaction();        String hql=("from User u where u.username=? and u.password=?");         Query query=session.createQuery(hql);        query.setString(0,username);        query.setString(1,password);        if(query.list().size()>0)        {            user=(User)query.list().get(0);        }        session.getTransaction().commit();        return user;    }