【JAVA】Java 实现无限层级的树形结构的数据

Java 实现无限层级的树形结构的数据（使用递归方法）

实现数据结构

{
    "code": 200,
    "msg": "成功！",
    "data": [
        {
            "id": "3de54a2de215454f84b30f74da895613",
			"pid": "-1"
            "companyUUId": "5380748e53ee48f8a1b67d34f64c93cf",
            "companyId": "ZGBW0001",
            "companyName": "xxxx有限公司",
            "childrenList": [
                {
                    "id": "202257d84d424db0a3cfd7791e5faf0e",
					"pid": "5380748e53ee48f8a1b67d34f64c93cf"
					"companyUUId": "2a723da6f60241af911ebe814f0f45f0",
					"companyId": "ZGBW000100",
					"companyName": "xxxx有限公司",
					"childrenList": [
						"id": "3258407ffa22434a8f353418f364dc5f",
						"pid": "2a723da6f60241af911ebe814f0f45f0"
						"companyUUId": "2b653a424a0c4ecdbfcab2d6bf78e160",
						"companyId": "ZGBW000199",
						"companyName": "xxxx有限公司",
						"childrenList": []
					]
                }
            ]
        }
    ]
}

1.创建实体类

2、创建返回Vo类
因为我这边使用的是mybatis-plus自带的增删改查方法，所以不能在实体类中新增其他属性

3、查询数据并组装成无线层级树状结构
使用递归方法实现树状结构

public List<AmpCompanyResponse> getCompanyLevel() {
   BaseApiService<Object> baseApiService = new BaseApiService<>();
   // 查询所有公司
   List<AmpCompanyTemporary> AmpList = ampCompanyTemporaryMapper.selectList(new QueryWrapper<AmpCompanyTemporary>().lambda()
           .orderByDesc(AmpCompanyTemporary::getCompanyLevel)
         .orderByAsc(AmpCompanyTemporary::getId));
  // 在此转把List转换为list
  List<AmpCompanyResponse> bList = AmpList.stream().map(ampCompanyTemporary -> {
      AmpCompanyResponse ampCompanyResponse = new AmpCompanyResponse();
      BeanUtils.copyProperties(ampCompanyTemporary, ampCompanyResponse);
      return ampCompanyResponse;
  }).collect(Collectors.toList());

  // 存放树结构的数据
  List<AmpCompanyResponse> ampCompanyTreeList = new ArrayList<>();
  if (bList.size() > 0 && bList != null) {
      // 找到所有的一级节点存放在一个list中
      List<AmpCompanyResponse> parntList = new ArrayList<>();
      for (AmpCompanyResponse pList : bList) {
      	// 父节点的pID为 -1，这边按自己实际情况来判断
          if ("-1".equals(pList.getPId())) {
              parntList.add(pList);
          }
      }
      // 为一级节点设置子节点 ,getChildren采用递归算法
      for (AmpCompanyResponse amp : parntList) {
          AmpCompanyResponse companyResponse = new AmpCompanyResponse();
          companyResponse = amp;
          companyResponse.setChildrenList(getChildren(amp.getCompanyUUId(), bList));
          ampCompanyTreeList.add(amp);
      }
  }
  return ampCompanyTreeList;
}

/**
  * 递归组装树节点数据
  *
  * @param id   父节点id
  * @param list 所有数据
  * @return
*/
public List<AmpCompanyResponse> getChildren(String id, List<AmpCompanyResponse> list) {
  List<AmpCompanyResponse> childrenList = new ArrayList<>();
  // 子节点
  for (AmpCompanyResponse children : list) {
      if (id.equals(children.getPId())) {
          childrenList.add(children);
      }
  }
   // 把子节点的子节点循环一遍
  for (AmpCompanyResponse cList : childrenList) {
      cList.setChildrenList(getChildren(cList.getCompanyUUId(),list));
  }
  return childrenList;
}

效果：