后端提供树形结构数据

Posted 2021-12-28 可小辉

一.简介
在项目开发中经常有需要处理树形结构的业务需求。比如具有父子关系的数据信息，而对于这种产品，在设计数据库时使用id<->parentId的结构来做。为方便前端,所以在给前端数据时，最好的做法就是把数据处理成treeJson格式。本文以公司-部门为例
以下测试基于springboot框架
二.关键代码
DepartEntity 公司-部门实体类

@Data
@TableName("sys_depart")
public class DepartEntity 
    private Integer departId;
    private String departName;
    /**
     * 顶层（公司）- company 时值为0或者null
     */
    private Integer parentId;
    /**
     * 顶层（公司）- company 次级（部门） department
     */
    private String type;
    /**
     * 该属性返回数据时使用
     */
    private List<DepartEntity> children;

获取树形结构方法(使用jdk8 新方法,简化代码)

private List getDepartmentTree(List list) 

<Map> groupMap = list.stream().collect(Collectors.groupingBy(DepartEntity::getType));

List companyList = groupMap.get("company");

List departmentList = groupMap.get("department");

if (companyList !=null && !companyList.isEmpty()) 

if (departmentList !=null && !departmentList.isEmpty()) 

<Map> departGroupMap = departmentList.stream().collect(Collectors.groupingBy(DepartEntity::getParentId));

for (DepartEntity company : companyList) 

company.setChildren(departGroupMap.get(company.getDepartId()));





return companyList;



return new ArrayList<>();

三.测试(数据自己造的，实际需要从数据库表中查询)

 @GetMapping("/tree/list")
    @ResponseBody
    public List<DepartEntity> testTree() 
        DepartEntity depart1 = new DepartEntity();
        depart1.setDepartId(1);
        depart1.setDepartName("公司");
        depart1.setParentId(0);
        depart1.setType("company");
        DepartEntity depart2 = new DepartEntity();
        depart2.setDepartId(2);
        depart2.setDepartName("财务部");
        depart2.setParentId(1);
        depart2.setType("department");
        DepartEntity depart3 = new DepartEntity();
        depart3.setDepartId(2);
        depart3.setDepartName("项目部");
        depart3.setParentId(1);
        depart3.setType("department");
        ArrayList<DepartEntity> list = new ArrayList<>();
        list.add(depart1);
        list.add(depart2);
        list.add(depart3);
        return getDepartmentTree(list);
    

四.工具测试（使用Apifox测试 使用方式和postman相似）

treeJson格式数据

[
    
        "departId": 1,
        "departName": "公司",
        "parentId": 0,
        "sort": null,
        "type": "company",
        "status": null,
        "createTime": null,
        "children": [
            
                "departId": 2,
                "departName": "财务部",
                "parentId": 1,
                "sort": null,
                "type": "department",
                "status": null,
                "createTime": null,
                "children": null
            ,
            
                "departId": 2,
                "departName": "项目部",
                "parentId": 1,
                "sort": null,
                "type": "department",
                "status": null,
                "createTime": null,
                "children": null
            
        ]
    
]