开始

1. 在接口中加入方法

public Home getByHomeId(@Param("id") int id);

2.在mapper配置文件中编写对应的标签

<resultMap id="home" type="com.example.mybatis.Home">
     <id property="id" column="h_id"/>
     <id property="name" column="h_name"/>
     <association property="proper" javaType="com.example.mybatis.Proper">
         <id property="id" column="p_id"/>
         <id property="name" column="p_name"/>
         <id property="meg" column="p_meg"/>
     </association>
 </resultMap>
 <select id="getByHomeId" parameterType="int" resultMap="home">
     select h.id as h_id,
            h.name as h_name,
            p.name as p_name,
            p.id as p_id,
            p.meg as p_meg
     from home as h join proper as p  on p.id = h.master
     where h.id=#{id};
 </select>

4. 测试

SqlSessionFactory sqlSessionFactory=SessionFactory.getSessionFactory();
		try (SqlSession sqlSession=sqlSessionFactory.openSession()){
			t1Mapper mapper = sqlSession.getMapper(t1Mapper.class);
			Home byHomeId = mapper.getByHomeId(1);
			System.out.println(byHomeId.toString());
		}

注意

• 对象中的对象映射用 association标签
• 注意resultMap中的javaType
• 注意select中的resultMap