Mybaits利用resultMap实现一对多

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对于一对多的resultMap的定义

<resultMap type="dancheng.mybatis.po.Orders" id="OrderUserResultMap">    <!-- 配置映射的订单信息 -->    <id column="id" property="id" />    <result column="user_id" property="userId" />    <result column="number" property="number" />    <result column="createtime" property="createtime" />    <result column="note" property="note" />        <!-- 配置映射关联信息 -->    <!-- association：用于映射关联查询单个对象的信息 property：要将关联查询的用户信息映射到Orders中哪个属性 -->    <association property="user" javaType="dancheng.mybatis.po.User">        <!-- id：关联查询用户的唯一标识 -->        <id column="user_id" property="id" />        <result column="username" property="username" />        <result column="sex" property="sex" />        <result column="address" property="address" />    </association></resultMap><!-- 查询订单及订单明细的resultMap --><resultMap type="dancheng.mybatis.po.Orders" id="OrderAndOrderDetailResultMap" extends="OrderUserResultMap">    <!-- 订单信息 -->    <!-- 用户信息 -->        <!-- 订单明细信息        一个订单关联查询出了多条明细 ，要是用collocation进行映射        collocation：对关联查询到的多条记录映射到集合对象中        porperty：将关联查询到多条记录映射到dancheng.mybatis.po.Orders的哪个属性        ofType：指定映射到list集合属性中pojo的类型     -->     <collection property="orderdetails" ofType="dancheng.mybatis.po.Orderdetail">         <!-- 订单明细的唯一标识  -->         <id column="id" property="id"/>         <result column="items_id" property="itemsId"/>         <result column="items_num" property="itemsNum"/>         <result column="orders_id" property="ordersId"/>     </collection>    </resultMap>

调用resultMap

<select id="findOrderAndOrderDetailResultMap" resultMap="OrderAndOrderDetailResultMap">    SELECT        orders.*,        user.username,        user.sex,        user.address,        orderdetail.*    FROM orders,        USER,        orderdetail    WHERE orders.user_id = user.id AND orderdetail.orders_id = orders.id</select>

mapper中的接口

public List<Orders> findOrderAndOrderDetailResultMap() throws Exception;

Test

public class OrdersMapperCustomTest {    private SqlSessionFactory sqlSessionFactory;    @Before    public void setUp() throws Exception {        InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);    }        @Test    public void testFindOrderAndOrderDetailResultMap() throws Exception {        SqlSession sqlSession = sqlSessionFactory.openSession();        OrdersMapperCustom ordersMapperCustom = sqlSession.getMapper(OrdersMapperCustom.class);                List<Orders> orderList = ordersMapperCustom.findOrderAndOrderDetailResultMap();                System.out.println(orderList);    }}

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