Mybatis-04-分页

分页

思考：为什么要分页？

• 减少数据的处理量

1 使用limit分页

select * from user limit startIndex,pageSize;

使用Mybatis实现分页，核心是SQL

1. 接口

List<User> getUserByLimit(HashMap<String,Integer> map);

1. Mapper.XML

<!--分页-->
<select id="getUserByLimit" parameterType="map" resultType="User">
    select * from mybatis.user limit #{startIndex},#{pageSize};
</select>

1. 测试

   @Test
   public void getUserByLimit(){
       SqlSession sqlSession = MybatisUtils.getSqlSession();
       UserMapper mapper = sqlSession.getMapper(UserMapper.class);
   
       HashMap<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();
   }
   

   

keymap： list.for 可以快速生成增强for循环

2 RowBounds分页

不再使用SQL实现分页

1. 接口

   List<User> getUserByRowBounds();
   

   

1. mapper.xml

   <!--分页-->
   <select id="getUserByRowBounds" resultType="User">
       select * from mybatis.user ;
   </select>
   

   

2. 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.kuang.dao.UserMapper.getUserByRowBounds",null,rowBounds);
       for (User user : userList) {
           System.out.println(user);
       }
       sqlSession.close();
   }
   

   

3 分页插件

Mybatis pageHelper