1、分页

思考：为什么要分页？

• 缩小数据的处理量

应用 Limit 分页

# 语法：SELECT * FROM `user` LIMIT startIndex,pageSize;

# [0,3]
SELECT * FROM `user` LIMIT 3;

应用 Mybatis 实现分页，外围 SQL
1. 接口

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

2.Mapper.xml

<resultMap id="UserMap" type="User">
    <!--column 数据库中的字段，property 实体类中的属性 -->
    <result column="id" property="id"/>
    <result column="name" property="name"/>
    <result column="pwd" property="password"/>
</resultMap>
<select id="getUserByLimit" 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(UserDao.class);

    Map<String,Integer> map = new HashMap<>();
    map.put("startIndex",0);
    map.put("pageSize",2);

    List<User> userList = mapper.getUserByLimit(map);
    for(User user:userList){System.out.println(user);
    }

    // 敞开
    sqlSession.close();}