目录

前言:

项目结构:

myuser类:

post类:

启动类:

controller:

mapper接口

Mapper.xml

数据库表结构:

一对多返回格式  (这里主要为 一个用户拥有多个文章):

前言:

项目结构:

myuser类:

post类:

启动类:

controller:

mapper接口

Mapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.luo.mybatisdemo.dao.MyUserMapper">
    <!-- User 级联文章查询 方法配置 (一个用户对多个文章)  -->

    <resultMap type="com.luo.mybatisdemo.entity.MyUser" id="resultUserMap">
        <result property="id" column="id" />
        <result property="username" column="username" />
        <result property="mobile" column="mobile" />
        <collection property="posts" ofType="com.luo.mybatisdemo.entity.Post" >
            <id property="id" column="post_id" />
            <result property="title" column="title" />
            <result property="content" column="content"  />
            <result property="userid" column="userid"  />

        </collection>
    </resultMap>

    <select id="getAllBooks" resultMap="resultUserMap">
		SELECT u.*,p.*
		FROM myuser u, post p
		WHERE u.id=p.userid AND u.id=#{user_id}
  </select>

</mapper>

数据库表结构:

post表:

myuser表:

一对多返回格式  (这里主要为 一个用户拥有多个文章):