list<>中的类型的作用是什么?mybatis的xml文件中设置的resultType是Vo,对应接口中的方法是List<UserEntity> queryOrderAndUserByType();
测试输出的是Vo的数据,那List<>尖括号总的数据类型起什么作用呢?
xml文件:
<select id="queryOrderAndUserByType" resultType="orderAndUserVo"> SELECT o.id,o.order_Number orderNumber,o.createtime,o.describer,o.user_id userId,u.tid,u.uname FROM orders o,t_user u WHERE u.tid=o.user_id </select>
对应接口类:
List<OrdersEntity> queryOrderAndUserByType();
测试类:
@Test public void queryOrderAndUserByType(){ SqlSession sqlSession = sqlSessionFactory.openSession(); OrdersMapper mapper = sqlSession.getMapper(OrdersMapper.class); List<OrdersEntity> ordersEntities = mapper.queryOrderAndUserByType(); for (OrdersEntity ordersEntity : ordersEntities) { System.out.println(ordersEntity); } }
输出结果: