Mybatis之分页

Mybatis

7、分页

7.1、思考：为什么要分页？

• 减少数据的处理量。

7.2、使用limit分页

• 语法：select * from user limit startIndex,pageSize;
  select * from user limit 2,2;   #[0，n]
  

• 接口

  • //分页
     List<User> getUserByLimit(Map<String,Integer> map);
    

• Mapper.xml

  •  <select id="getUserByLimit" parameterType="map" resultMap="UserMap">
            select * from ibatis.user limit #{startIndex},#{pageSize}
     </select>
    

• 测试

  • static  Logger logger = Logger.getLogger(UserMapperTest.class);
        @Test
        public void testGetUserByLimit(){
            SqlSession sqlSession = MybatisUtils.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            HashMap<String, Integer> map = new HashMap<String, Integer>();
             map.put("startIndex",1);
             map.put("pageSize",2);
            List<User> userByLimit = mapper.getUserByLimit(map);
            for (User user : userByLimit) {
                System.out.println(user);
            }
            sqlSession.close();
        }
    

7.3、RowBounds分页

• 接口

  • //分页2
        List<User> getUserByRowBounds();
    

• mapper.xml

  •  <!--分页2-->
        <select id="getUserByRowBounds" resultMap="UserMap">
            select * from user
        </select>
    

• 测试

  •  @Test
        public void getuserByRowBounds() {
            SqlSession sqlSession = MybatisUtils.getSqlSession();
            //RowBounds实现
            RowBounds rowBounds = new RowBounds(1, 2);
            // 通过Java代码层面实现分页
            List<User> userList = sqlSession.selectList("com.jcooling.mapper.UserMapper.getUserByRowBounds",null,rowBounds);
            for (User user : userList) {
                System.out.println(user);
            }
            sqlSession.close();
        } 
    

7.4、分页插件

• pagehelper