前端页面展示数据树形数据时,需要我们返回一定的数据格式,这样的情况有两种解决办法,一种是进行字符串拼接,另一种是编写对应的实体类。下面是以实体类的方式进行解决。
课程分类列表树形显示.png
第一种实现方式
一、编写实体类
一级分类
package com.caiweiwei.eduservice.entity.subject;
import lombok.Data;
import java.util.ArrayList;
import java.util.List;
@Data
public class OneSubject {
private String id;
private String title;
private List<TwoSubject> children=new ArrayList<>();
}
二级分类
package com.caiweiwei.eduservice.entity.subject;
import lombok.Data;
@Data
public class TwoSubject {
private String id;
private String title;
}
二、controller层
/**
* 功能描述:课程分类列表(树形)
* @Author: caiweiwei
* @Date: 2020/9/16 9:47
*/
@GetMapping("/sublectList")
public R getAllSubject(){
//list的泛型是一级分类
List<OneSubject>list= eduSubjectService.getAllOneTwoSubject();
return R.ok().data("list",list);
}
三、service层
/**
* 功能描述:查询一级分类和二级分类并进行封装
*
* @Author: caiweiwei
* @Date: 2020/9/16 10:12
*/
@Override
public List<OneSubject> getAllOneTwoSubject() {
//查询一级分类
QueryWrapper<EduSubject> oneSubjectQueryWrapper = new QueryWrapper<>();
oneSubjectQueryWrapper.eq("parent_id", "0");
List<EduSubject> oneSubjects = baseMapper.selectList(oneSubjectQueryWrapper);
//查询二级分类
QueryWrapper<EduSubject> twoSubjectQueryWrapper = new QueryWrapper<>();
oneSubjectQueryWrapper.ne("parent_id", "0");
List<EduSubject> twoSubjects = baseMapper.selectList(twoSubjectQueryWrapper);
List<OneSubject> oneSubjectList = new ArrayList<>();
//封装一级分类
for (int i = 0; i < oneSubjects.size(); i++) {
EduSubject eduSubject = oneSubjects.get(i);
OneSubject oneSubject = new OneSubject();
//将属性进行复制
BeanUtils.copyProperties(eduSubject, oneSubject);
//封装二级分类
List<TwoSubject> twoSubjectList = new ArrayList<>();
for (int j = 0; j < twoSubjects.size(); j++) {
if(twoSubjects.get(j).getParentId().equals(eduSubject.getId())){
TwoSubject twoSubject = new TwoSubject();
//将属性进行赋值
BeanUtils.copyProperties(twoSubjects.get(j), twoSubject);
twoSubjectList.add(twoSubject);
}
}
//将封装好的二级分类封装到一级分类的实体类中
oneSubject.setChildren(twoSubjectList);
oneSubjectList.add(oneSubject);
}
return oneSubjectList;
}
第二种实现方式
一、创建树形结构实体类
@Data
public class TreeDto {
private String id;
private String name;
private String pid;
private String isParent;
private List<TreeDto> childTreeDto;
}
二、创建树形工具类
public class TreeToolUtils {
private List<TreeDto> rootList; //根节点对象存放到这里
private List<TreeDto> bodyList; //其他节点存放到这里，可以包含根节点
public TreeToolUtils(List<TreeDto> rootList, List<TreeDto> bodyList) {
this.rootList = rootList;
this.bodyList = bodyList;
}
public List<TreeDto> getTree(){ //调用的方法入口
if(bodyList != null && !bodyList.isEmpty()){
//声明一个map，用来过滤已操作过的数据
Map<String,String> map = Maps.newHashMapWithExpectedSize(bodyList.size());
rootList.forEach(beanTree -> getChild(beanTree,map));
return rootList;
}
return null;
}
public void getChild(TreeDto treeDto,Map<String,String> map){
List<TreeDto> childList = Lists.newArrayList();
bodyList.stream()
.filter(c -> !map.containsKey(c.getId()))
.filter(c ->c.getPid().equals(treeDto.getId()))
.forEach(c ->{
map.put(c.getId(),c.getPid());
getChild(c,map);
childList.add(c);
});
treeDto.setChildTreeDto(childList);
}
}
三、使用main方法进行测试
TreeDto treeDto = new TreeDto("1", "总店", "null", "true",null);
TreeDto treeDto1 = new TreeDto("2", "市分店", "1", "true",null);
TreeDto treeDto2 = new TreeDto("3", "县分店", "2", "true",null);
TreeDto treeDto3 = new TreeDto("710", "店长", "3", "true",null);
TreeDto treeDto4= new TreeDto("713", "财务部", "3", "true",null);
TreeDto treeDto5 = new TreeDto("20032", "后勤部", "3", "true",null);
TreeDto treeDto6 = new TreeDto("1909", "小王", "710", "false",null);
TreeDto treeDto7= new TreeDto("1974", "小张", "713", "false",null);
TreeDto treeDto8 = new TreeDto("388187", "佳佳", "20032", "false",null);
TreeDto treeDto9 = new TreeDto("1949", "阿达", "20032", "false",null);
ArrayList<TreeDto> rootList = new ArrayList<>();//根节点
ArrayList<TreeDto> bodyList = new ArrayList<>();//子节点
rootList.add(treeDto);
bodyList.add(treeDto1);
bodyList.add(treeDto2);
bodyList.add(treeDto3);
bodyList.add(treeDto4);
bodyList.add(treeDto5);
bodyList.add(treeDto6);
bodyList.add(treeDto7);
bodyList.add(treeDto8);
bodyList.add(treeDto9);
TreeToolUtils utils = new TreeToolUtils(rootList,bodyList);
List<TreeDto> result = utils.getTree();
String jsonString = JSONObject.toJSONString(result.get(0));
System.out.println(jsonString);
}
四、控制台输出样式
{
"childTreeDto": [{
"childTreeDto": [{
"childTreeDto": [{
"childTreeDto": [{
"childTreeDto": [],
"id": "1909",
"isParent": "false",
"name": "小王",
"pid": "710"
}],
"id": "710",
"isParent": "true",
"name": "店长",
"pid": "3"
}, {
"childTreeDto": [{
"childTreeDto": [],
"id": "1974",
"isParent": "false",
"name": "小张",
"pid": "713"
}],
"id": "713",
"isParent": "true",
"name": "财务部",
"pid": "3"
}, {
"childTreeDto": [{
"childTreeDto": [],
"id": "388187",
"isParent": "false",
"name": "佳佳",
"pid": "20032"
}, {
"childTreeDto": [],
"id": "1949",
"isParent": "false",
"name": "阿达",
"pid": "20032"
}],
"id": "20032",
"isParent": "true",
"name": "后勤部",
"pid": "3"
}],
"id": "3",
"isParent": "true",
"name": "县分店",
"pid": "2"
}],
"id": "2",
"isParent": "true",
"name": "市分店",
"pid": "1"
}],
"id": "1",
"isParent": "true",
"name": "总店",
"pid": "null"
}
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