为何要分页

• 减少数据处理量
• 便于前端展示数据

使用Limit分页

语法结构

SELECT * FROM user LIMIT startIndex,pageSize;
SELECT * FROM user LIMIT 0,5;
## 从头查询三个
SELECT * FROM user LIMIT 3;

结合Mybatis实现分页，核心SQL（LIMIT）

• 接口

// 用户分页查询
// 通过Map灵活传参
List<User> getUserByLimit(Map<String, Integer> map);

• Mapper.xml

<!--用户分页查询-->
<select id="getUserByLimit" resultMap="UserMap">
    SELECT * FROM user LIMIT #{startIndex},#{pageSize};
</select>

• 测试

@Test
public void getUserByLimitTest() {
    SqlSession sqlSession = MybatisUtils.getSqlSession();
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    HashMap<String, Integer> hashMap = new HashMap<String, Integer>();
    hashMap.put("startIndex",0);
    hashMap.put("pageSize",5);
    List<User> userList = mapper.getUserByLimit(hashMap);
    for ( User user : userList) {
        System.out.println(user);
    }
    sqlSession.close();
}