hibernate_分页查询

Posted 2021-06-15 nirvana · rebirth

 	@Test
    public void test() {
        SessionFactory sf = null;
        Session session = null;
        Transaction ts = null;
        try {
            sf = HibernateUtil.getSessionFactory();
            session = sf.getCurrentSession();
            ts = session.beginTransaction();    // 开始事务
            // Query query = session.createQuery("from User as u where (u.age > (select avg(u.age) from User as u)) ");
            // Query query = session.createQuery("from User as u order by u.birthday,u.name desc");
            // Query query = session.createQuery("select u.gender, avg(u.age), count(*) from User as u group by u.gender having avg(u.age) > 21 ");
            // Query query = session.createQuery("from User as u where u.name like ?1 and u.age > ?2");
            //query.setParameter(1, "%王%");
            //query.setParameter(2, 10);
            
            Query query = session.createQuery("from User");
            
            int n1 = 3, n2 = 10;	// 每页十条记录，查询第三页
            /*
            * setFirstResult下标从0开始计算，第n1页前，共n2*(n1-1)条记录
            * 当前记录id应该为n2*(n1-1)+1
            * 下标从零开始计算，所以传参应该为：n2*(n1-1)+1-1=n2*(n1-1)
            */ 
            query.setFirstResult(n2 * (n1 - 1)).setMaxResults(n2); 
            
            List<User> list = query.list();
            for (int i = 0; i < list.size(); ++i) 
                System.out.println(list.get(i));
            ts.commit();    // 提交事务
        } catch (Exception e) {
            e.printStackTrace();
            if (ts != null) {
                ts.rollback();  // 回滚
            }
        } 
    }