Mybatis学习分页
为什么要分页
- 减少数据的使用量
使用Limit分页
语法:select * from user limit startIndex,pageSize;
select * from user limit 3; #[0,3]
使用Mybatis实现分页,核心SQL
- 接口
// 分页
List<User> getUserByLimit(Map<String,Integer> map);
- Mapper.xml
<!--分页-->
<select id="getUserByLimit" parameterType="map" resultMap="UserMap">
select * from user limit #{startIndex},#{pageSize}
</select>
- 测试
@Test
public void getUserByLimit(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
HashMap<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);
}
sqlSession.close();
}
RowBounds分页
不在使用SQL实现分页
- 接口
// 分页2
List<User> getUserByRowBounds();
- mapper.xml
<select id="getUserByRowBounds" resultMap="UserMap">
select * from user
</select>
- 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.lyh.dao.UserMapper.getUserByRowBounds",null,rowBounds);
for (User user: userList){
System.out.println(user);
}
sqlSession.close();
}
分页插件
Mybatis PageHelper官方文档:https://pagehelper.github.io/docs/