文章目录
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<SceneVO>
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<SubSceneVO> 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);
}
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="你的包名.mapper.BusinessScenesCustomMapper">
<resultMap id="BaseResultMap" type="你的包名.vo.SceneVO">
<result column="session_id" jdbcType="VARCHAR" property="sessionId"/>
<!-- collection 标签:用于定义关联的list集合类型的封装规则 property:对应父类中list属性名,这里SceneVO类里的List变量名为sceneList ofType:集合存放的类型,List集合要装的类的类名,这里是SubSceneVO -->
<collection property="sceneList" ofType="你的包名.vo.SubSceneVO">
<result column="scene_id" jdbcType="VARCHAR" property="sceneId"/>
<result column="scene_name" jdbcType="VARCHAR" property="sceneName"/>
</collection>
</resultMap>
<!-- 一个session_id对应多条记录,返回的是SceneVO对象,SceneVO对象有一个List装着SubSceneVO -->
<select id="selectBySessionId" parameterType="string" resultMap="BaseResultMap">
select session_id, scene_id, scene_name
from 表名
where session_id = #{sessionId,jdbcType=VARCHAR}
</select>
</mapper>
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);
}
@Service
public class SceneServiceImpl {
@Resource
private BusinessScenesCustomMapper businessScenesCustomMapper;
......
public SceneVO getScenesInfo(String sessionId) {
return businessScenesCustomMapper.selectBySessionId(sessionId);
}
}
5.Controller层
......
@Resource
private SceneService sceneService;
@GetMapping("/getScenesInfo")
public ResModel getScenesInfo(String sessionId) {
SceneVO sceneVO = sceneService.getScenesInfo(sessionId);
return ResModel.ok(sceneVO);
}
欢迎一键三连~
有问题请留言,大家一起探讨学习
———————-Talk is cheap, show me the code———————–