4.实现分页

sql的语法

使用limit来实现 推荐 

select * from user limit 3;表示从头开始查找三个

select * from user limit 1，2；表示从第二个开始查找两个 

接口

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

xml

<!--分页 Map的别名是map 记得int的别名是_int Integer的别名是int-->
    <select id="getUserByLimit" parameterType="map" resultType="user">
        select * from mybatis.user limit #{start},#{pageSize}
    </select>

test

    @Test
    public void testLimit(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        Map<String, Integer> map = new HashMap<>();
        map.put("start",1);
        map.put("pageSize",2);
        List<User> userByLimit = mapper.getUserByLimit(map);
        userByLimit.forEach(System.out::println);
        sqlSession.close();
    }