通过递归的方式实现树形结构

背景介绍

我有一个部门的表结构，如果我获取到下列数据，如何通过后端来构造该公司的树形结构

代码

• POJO类

import java.util.List;

public class Company {
    
    private int id;//公司id
    private String name;//公司名称
    private int pid;//上级公司
    private List<Company> subCompanyList;//下游公司

    public Company() {
    
    }

    public Company(int id, String name, int pid) {
    
        this.id = id;
        this.name = name;
        this.pid = pid;
    }

    public int getId() {
    
        return id;
    }

    public void setId(int id) {
    
        this.id = id;
    }

    public String getName() {
    
        return name;
    }

    public void setName(String name) {
    
        this.name = name;
    }

    public int getPid() {
    
        return pid;
    }

    public void setPid(int pid) {
    
        this.pid = pid;
    }

    public List<Company> getSubCompanyList() {
    
        return subCompanyList;
    }

    public void setSubCompanyList(List<Company> subCompanyList) {
    
        this.subCompanyList = subCompanyList;
    }

    @Override
    public String toString() {
    
        return "Company{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", pid=" + pid +
                ", subCompanyList=" + subCompanyList +
                '}';
    }
}

• 递归方法

public static Company addSubCompany(Company company,List<Company> data){
    
        //构造一个子公司列表
        List<Company> subCompany = new ArrayList<>();
        for(Company item: data){
    //遍历数据
        	//如果遍历到的部门是当前部门的子部门
            if(item.getPid() == company.getId()){
    
                //把遍历到的公司添加到子公司列表，并且递归地调用本方法
                subCompany.add(addSubCompany(item,data));
            }
        }
        company.setSubCompanyList(subCompany);
        return company;
    }

• 具体测试类
  这里为了方便，就不搞DAO层了，自己模拟一些数据代替

public static void main(String[] args) {
    
        List<Company> data = new ArrayList<>();
        Company c1 = new Company(1,"总公司",-1);
        Company c2 = new Company(10,"财务部",1);
        Company c3 = new Company(11,"市场部",1);
        Company c4 = new Company(12,"研发部",1);
        Company c5 = new Company(100,"财务小组1",10);
        Company c6 = new Company(101,"财务小组2",10);
        Company c7 = new Company(110,"市场小组1",11);
        Company c8 = new Company(111,"市场小组2",11);
        Company c9 = new Company(120,"研发小组1",12);
        Company c10 = new Company(121,"研发小组2",12);
        data.add(c1);data.add(c2);data.add(c3);data.add(c4);data.add(c5);
        data.add(c6);data.add(c7);data.add(c8);data.add(c9);data.add(c10);
        addSubCompany(c1,data);
        System.out.println(c1);
    }

运行结果

Company{
    id=1, name='总公司', pid=-1, subCompanyList=[Company{
    id=10, name='财务部', pid=1, subCompanyList=[Company{
    id=100, name='财务小组1', pid=10, subCompanyList=[]}, Company{
    id=101, name='财务小组2', pid=10, subCompanyList=[]}]}, Company{
    id=11, name='市场部', pid=1, subCompanyList=[Company{
    id=110, name='市场小组1', pid=11, subCompanyList=[]}, Company{
    id=111, name='市场小组2', pid=11, subCompanyList=[]}]}, Company{
    id=12, name='研发部', pid=1, subCompanyList=[Company{
    id=120, name='研发小组1', pid=12, subCompanyList=[]}, Company{
    id=121, name='研发小组2', pid=12, subCompanyList=[]}]}]}

Process finished with exit code 0