使用spring jpa 时,利用nativeQuery,获取数据,无需新建实体,按照别名返回Json数据

刚开始是这样写的

    @Query(value = "SELECT ll.user_id id ,u.catong_img catong_img,ll.locationId location_id,ll.address address,ll.latitude latitude,ll.longitude longitude,ll.update_time update_time,ll.user_id user_id FROM t_user as u left JOIN (SELECT l.id locationId, address,latitude,longitude,l.update_time,l.user_id FROM t_user_location AS l RIGHT JOIN ( SELECT user_id, max( update_time ) update_time FROM t_user_location GROUP BY user_id ) AS t ON l.user_id = t.user_id AND l.update_time = t.update_time ) ll ON u.zu_id =?1 and u.id = ll.user_id",nativeQuery = true)
    @Transactional
    List getAllUserLocationByZuId(long zuId);

发现返回的数据是这样的,设置的别名没有返回

[
  [
    1,
    "吕志豪",
    "",
    3,
    "3",
    3,
    3,
    1513670259000,
    1
  ],
  [
    2,
    "胡勇",
    "",
    2,
    "2",
    2,
    2,
    1513151843000,
    2
  ]
]

之后是这样写的,使用EntityManager

    @PersistenceContext
    private EntityManager em;
    @Override
    public List getAllUserLocation(long zuId) {
       return em.createNativeQuery("SELECT  u.name name ,u.catong_img catongImg,ll.locationId locationId,ll.address address,ll.latitude latitude,ll.longitude longitude,ll.update_time updateTime,ll.user_id userId FROM t_user as u left JOIN (SELECT l.id locationId, address,latitude,longitude,l.update_time,l.user_id FROM t_user_location AS l RIGHT JOIN ( SELECT user_id, max( update_time ) update_time FROM t_user_location GROUP BY user_id ) AS t ON l.user_id = t.user_id AND l.update_time = t.update_time ) ll ON u.zu_id =1 and u.id = ll.user_id")
        .unwrap(SQLQuery.class)
                .setResultTransformer(
                        AliasToEntityMapResultTransformer.INSTANCE
                )
                .list();
    }

结果返回

[
  {
    "catongImg": "",
    "address": "3",
    "locationId": 3,
    "latitude": 3,
    "name": "吕志豪",
    "updateTime": 1513670259000,
    "userId": 1,
    "longitude": 3
  },
  {
    "catongImg": "",
    "address": "2",
    "locationId": 2,
    "latitude": 2,
    "name": "胡勇",
    "updateTime": 1513151843000,
    "userId": 2,
    "longitude": 2
  }
]

原文地址：https://www.jianshu.com/p/e6bc577d03f0