Mybatis07：分页

7、分页

思考：为啥要分页？？

• 减少数据的处理量，查询快速

7.1、使用limit分页

SELECT * FROM USER LIMIT 0, 2;  -- 每页显示两个从第0个开始查，步长为2
SELECT * FROM USER LIMIT 4; -- 从第0个开始查，一直到第n个[0, n]

使用Mybatis实现分页，核心就是SQL

1. 接口

   //分页查询
   public List<User> getUserByLimit(Map<String, Integer> map);
   

2. Mapper.xml

   <select id="getUserByLimit" resultMap="User" parameterType="map">
       select * from mybatisdb.user limit #{startIndex}, #{pageSize};
   </select>
   

3. 测试

   @Test
   public void getUserByLimit() {
       SqlSession sqlSession = MybatisUtils.getSqlSession();
       UserDao mapper = sqlSession.getMapper(UserDao.class);
   
       Map<String, Integer> map = new HashMap<String, Integer>();
       map.put("startIndex", 0);
       map.put("pageSize", 2);
       List<User> user = mapper.getUserByLimit(map);
       for (User user1 : user) {
           System.out.println(user1);
       }
   
       sqlSession.close();
   }
   

7.2、RowBounds分页