mybatis 懒加载

延迟加载：

xml中的配置：

<!-- #######################################延迟加载####################################################### -->
	<resultMap type="cn.itcast.domain.Orders" id="OrdersUserLazyLoading">
		<id column="id" property="id"/>
		<result column="number" property="number"/>
		<result column="createtime" property="createtime"/>
		<result column="note" property="note"/>
		<result column="user_id" property="userId"/>
		<!-- 
			select:指定延迟加载需要执行的statement的id 用到了 不同的命名空间下的id因此要使用命名空空间
			column:订单信息中关联用户信息查询的列 是外键user_id
		 -->
		<association property="user" javaType="cn.itcast.domain.User" select="cn.itcast.mapper.UserMapper.findById" column="user_id">
		</association>
	</resultMap>
	<select id="findOrdersUserLazyLoading" resultMap="OrdersUserLazyLoading">
		select * from orders
	</select>
	<select id="findOrdersUser" resultType="cn.itcast.domain.OrdersUser">
		select orders.*,user.username,user.sex,user.address
		from orders,user
		where orders.user_id=user.id
	</select>

接口中定义方法

public List<Orders> findOrdersUserLazyLoading();

测试：

@Test
	public void testfindOrdersUserLazyLoading(){
		SqlSession sqlSession = sqlSessionFactory.openSession();
		 OrdersMapperUser ordersMapperUser = sqlSession.getMapper(OrdersMapperUser.class);
		List<Orders> list = ordersMapperUser.findOrdersUserLazyLoading();
		//遍历上面的list
		for(Orders order:list){
			User user = order.getUser();
			System.out.println(user);
		}
	}

测试分析：

通过debug模式：