SSM框架学习之路-Mybatis（七）分页

7、分页

**思考：**为什么要使用分页？

• 减少数据处理量

使用Limit分页

-- 语法： select * from mybatis.user limit startIndex, pageSize;
select * from mybatis.user limit 3; -- [0, n]

使用Mybatis分页，核心SQL

1. 接口

   // 分页获取用户
   public List<User> getUserByLimit(Map<String, Integer> map);
   

2. Mapper.xml

   
   <select id="getU serByLimit" parameterType="map" resultMap="userMap">
       select * from mybatis.user limit #{startIndex}, #{pageSize}
   select>
   

3. 测试

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

7.2、RowBounds分页

不再使用SQL实现分页

1. 接口

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

2. Mapper.xml

   
   <select id="getUserByRowBounds" resultMap="userMap">
       select * from mybatis.user
   select>
   

3. 测试

   @Test
   public void getUserByRowBounds() {
       SqlSession sqlSession = MybatisUtils.getSqlSession();
       // RowBounds实现
       RowBounds rowBounds = new RowBounds(1, 2);
       // 通过java代码层实现分页
       List<User> users = sqlSession.selectList("com.wsw.dao.UserMapper.getUserByRowBounds", null, rowBounds);
       for (User user : users) {
           System.out.println(user);
       }
       sqlSession.close();
   }
   

7.3、分页插件

了解即可，需要知道它是什么东西。