Mybatis注解开发(一对一)

其他代码访问：Mybatis注解开发基础操作

1.添加OrderMapper接口

public interface OrderMapper {
//    @Select("select *,o.id oid from orders o,user u where o.uid=u.id")
//    @Results({
//            @Result(column = "oid",property = "id"),
//            @Result(column = "ordertime",property = "ordertime"),
//            @Result(column = "uid",property = "user.id"),
//            @Result(column = "username",property = "user.username"),
//            @Result(column = "password",property = "user.password")
//    })
//    public List<Order> findAll();
    @Select("select * from orders")
    @Results({
            @Result(column = "oid",property = "id"),
            @Result(column = "ordertime",property = "ordertime"),
            @Result(column = "total",property = "total"),
            @Result(
                    property = "user",//要封装的属性名称
                    column = "uid", //根据哪个字段进行查询User表的字段
                    javaType = User.class,//要封装的实体类型
                    //select属性，代表查询查询哪个接口方法获得数据
                    one = @One(select ="com.hao.mapper.UserMapper.findById")
            )
    })
    public List<Order> findAll();
    }

2.测试

public class MapperTest2 {
    private OrderMapper orderMapper;
    @Before
    public void before() throws IOException {
        InputStream stream = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactory build = new SqlSessionFactoryBuilder().build(stream);
        SqlSession sqlSession = build.openSession(true);
        orderMapper = sqlSession.getMapper(OrderMapper.class);
    }
    @Test
    public void testFindAll(){
        List<Order> list = orderMapper.findAll();
        for (Order order : list) {
            System.out.println(order);
        }
    }
}

测试结果：
Order{id=0, ordertime=Wed Dec 12 08:00:00 CST 2018, total=3000.0, user=User{id=1, username=‘lucy’, password=‘123’, birthday=Wed Dec 12 08:00:00 CST 2018}}
Order{id=0, ordertime=Wed Dec 12 08:00:00 CST 2018, total=4000.0, user=User{id=1, username=‘lucy’, password=‘123’, birthday=Wed Dec 12 08:00:00 CST 2018}}
Order{id=0, ordertime=Wed Dec 12 08:00:00 CST 2018, total=5000.0, user=User{id=2, username=‘dou’, password=‘bi’, birthday=null}}