mybatis中查询一对多实现【模型里有集合】

mybatis中查询一对多实现

mapper：

public interface OrderMapper {
    public Orders findOrderById3(int id);
}

xml配置：

        <!--  ================一对多==================-->
    <resultMap id="orderRslMap3" type="orders">
        <!-- 往orders的模型匹配数据-->
        <id column="id" property="id"></id>
        <id column="note" property="note"></id>
        <id column="number" property="number"></id>
        <id column="createtime" property="createtime"></id>

        <!-- 往orders的user匹配数据
         模型里有模型，使用association来配置-->
        <association property="user" javaType="user">
            <id column="user_id" property="id"></id>
            <id column="username" property="username"></id>
            <id column="address" property="address"></id>
        </association>
        
        <!-- 一对多匹配： 往orders的orderdetails 匹配数据
        注意：集合里类型使用ofType,而不javaType
        -->
        <collection property="orderDetails" ofType="orderDetail">
            <id column="detail_id" property="id"></id>
            <id column="items_id" property="itemsId"></id>
            <id column="items_num" property="itemsNum"></id>
        </collection>
    </resultMap>

测试类：

    //一对多，模型中有集合
    public class Demo01 {
	    SqlSession session;
	    @Before
	    public void before() throws IOException {
	        System.out.println("before....获取session");
	        //读取配置文件
	        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
	        //通过SqlSessionFactoryBuilder创建SqlSessionFactory会话工厂
	        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
	        //通过SqlSessionFactory创建SqlSession
	        session = sessionFactory.openSession();
	    }

	    @After
	    public void after(){
	        session.close();
	    }
	    @Test
	    public void test8() throws IOException {
	        OrderMapper mapper = session.getMapper(OrderMapper.class);
	        Orders order =  mapper.findOrderById3(3);
	        System.out.println(order);
	        System.out.println(order.getUser());
	        System.out.println(order.getOrderDetails());
	    }
  }