Java常用的类
1.业务背景
业务场景中，一个会话中存在多个场景，即一个session_id对应多个scene_id和scene_name
如果你写成如下的聚合模型类
public class SceneVO { private String sessionId; private String sceneId; private String sceneName; // 省略对应的getter和setter方法}
返回的List形式如下，这个数据在data属性中
{
"data":[
{
"sessionId": "jksadhjksd",
"sceneId":"NDJWKSDSJKDKED",
"sceneName":"场景1"
},
{
"sessionId": "jksadhjksd",
"sceneId":"KLJSDJKLSDFALK",
"sceneName":"场景2"
},
{
"sessionId": "jksadhjksd",
"sceneId":"KERFJKOVDJKDSS",
"sceneName":"场景3"
}
]}
每个对象里面都带上了重复的一个sessionId数据，我想提出来该怎么办？
我想改为如下形式，sessionId提出到外层，更能体现出一个sessionId对应多个sceneId和sceneName的含义，这样也便于前端取数据，不然每个对象都要增加一个sessionId属性，太麻烦。
{
"data": {
"sessionId": "jksadhjksd",
"sceneList": [
{
"sceneId":"NDJWKSDSJKDKED",
"sceneName":"场景1"
},
{
"sceneId":"KLJSDJKLSDFALK",
"sceneName":"场景2"
},
{
"sceneId":"KERFJKOVDJKDSS",
"sceneName":"场景3"
}
]
}}
2.实体类
方法如下：
首先创建两个实体类
public class SceneVO { private String sessionId; private List sceneList; // 省略对应的getter和setter方法}public class SubSceneVO { private String sceneId; private String sceneName; // 省略对应的getter和setter方法}
3.自定义Mapper和xml文件
public interface BusinessScenesCustomMapper {
SceneVO selectBySessionId(String sessionId);
}
select session_id, scene_id, scene_name
from 表名
where session_id = #{sessionId,jdbcType=VARCHAR}
-
collection标签： 用于定义关联的List集合类型的封装规则
-
property属性： 对应父类中List集合的变量名，这里SceneVO类里的List变量名为sceneList
-
ofType属性： 集合存放的类型，List集合要装的类的类名，这里是SubSceneVO
4.Service层
public interface SceneService { /**
* 获取场景信息
*/
SceneVO getScenesInfo(String sessionId);
}@Servicepublic class SceneServiceImpl { @Resource
private BusinessScenesCustomMapper businessScenesCustomMapper;
...... public SceneVO getScenesInfo(String sessionId) { return businessScenesCustomMapper.selectBySessionId(sessionId);
}
}
5.Controller层
......@Resourceprivate SceneService sceneService;@GetMapping("/getScenesInfo")public ResModel getScenesInfo(String sessionId) { SceneVO sceneVO = sceneService.getScenesInfo(sessionId); return ResModel.ok(sceneVO);
}