Java后端组装树形结构数据

2023-12-19 11:54| 来源: 网络整理| 查看: 265

项目开发中，几乎无法避免的会遇到树形结构，今天和大家分享java后端如何处理数据为树形结构。

1.封装测试实体类

package com.ldl.cn.demo; import java.util.ArrayList; import java.util.List; public class Dept { private int id; private int parentId; private String name; private List child = new ArrayList(); public Dept() { super(); } public Dept(int id, int parentId, String name) { super(); this.id = id; this.parentId = parentId; this.name = name; } public int getId() { return id; } public void setId(int id) { this.id = id; } public int getParentId() { return parentId; } public void setParentId(int parentId) { this.parentId = parentId; } public String getName() { return name; } public void setName(String name) { this.name = name; } public List getChild() { return child; } public void setChild(List child) { this.child = child; } @Override public String toString() { return " [id=" + id + ", parentId=" + parentId + ", name=" + name + ", child=" + child + "]"; } }

2.编写测试类

package com.ldl.cn.demo; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import cn.hutool.json.JSONUtil; public class TestDemo { private static List deptList; static { Dept dept1 = new Dept(1, 0, "中国"); Dept dept2 = new Dept(2, 1, "北京"); Dept dept3 = new Dept(3, 1, "上海"); Dept dept4 = new Dept(4, 1, "广东"); Dept dept5 = new Dept(5, 4, "广州"); Dept dept6 = new Dept(6, 4, "深圳"); Dept dept7 = new Dept(7, 5, "天河区"); deptList = new ArrayList(); deptList.add(dept1); deptList.add(dept2); deptList.add(dept3); deptList.add(dept4); deptList.add(dept5); deptList.add(dept6); deptList.add(dept7); } private static List buildTree(List deptList,int pid){ List treeList = new ArrayList(); for (Dept dept : deptList) { if (dept.getParentId() == pid) { dept.setChild(buildTree(deptList, dept.getId())); treeList.add(dept); } } return treeList; } public static void main(String[] args) { Map map = new HashMap(); map.put("data", buildTree(deptList, 1)); System.out.println(JSONUtil.toJsonStr(map)); } }

读者可以自行体会递归方法。

3.运行结果与分析

控制台输出：

{"data":[{"name":"北京","id":2,"parentId":1,"child":[]},{"name":"上海","id":3,"parentId":1,"child":[]},{"name":"广东","id":4,"parentId":1,"child":[{"name":"广州","id":5,"parentId":4,"child":[{"name":"天河区","id":7,"parentId":5,"child":[]}]},{"name":"深圳","id":6,"parentId":4,"child":[]}]}]}

使用JSON解析工具解析：

成功组装树形结构！

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