实现文件目录结构功能

package com.geespace.microservices.directory.assets.entity;

import java.util.ArrayList;
import java.util.List;

import lombok.Data;

/**
 * @Author: wjq
 * @Date: 2021-03-14 13:46
 * @Version 1.0
 */
@Data
public class Node {
    /**
     * 名称
     */
    private String name;
    /**
     * id
     */
    private Long id;
    /**
     * pid
     */
    private Long pid;
    /**
     * 子目录
     */
    private List<Node> children = new ArrayList();
}

package com.geespace.microservices.directory.assets.util;

import java.util.ArrayList;
import java.util.HashMap;

import com.alibaba.fastjson.JSONObject;
import com.geespace.microservices.directory.assets.dto.DirectoryAssetsDto;
import com.geespace.microservices.directory.assets.entity.Node;

import org.springframework.stereotype.Component;

/**
 * @Author: wjq
 * @Date: 2021-03-12 16:39
 * @Version 1.0
 */
@Component
public class ConstructTree {
    public static final int ROOTPID = -1;
    public static final int CAPACITY = 100;

    /**
     * constructLinks
     *
     * @param directoryList directoryList
     * @return 结果
     */
    public Node constructLinks(ArrayList<DirectoryAssetsDto> directoryList) {
        Long rootId = null;
        HashMap<Long, Node> nodeMap = new HashMap<>(CAPACITY);
        for (DirectoryAssetsDto directoryInfo:directoryList) {
            Node tempNode = new Node();
            tempNode.setId(directoryInfo.getId());
            tempNode.setName(directoryInfo.getName());
            tempNode.setPid(directoryInfo.getPid());
            nodeMap.put(directoryInfo.getId(), tempNode);
            if (directoryInfo.getPid() == ROOTPID) {
                rootId = directoryInfo.getId();
            }
        }
        for (Long key: nodeMap.keySet()) {
            Long pid = nodeMap.get(key).getPid();
            if (pid != ROOTPID) {
                nodeMap.get(pid).getChildren().add(nodeMap.get(key));
            }
        }
        Node root = nodeMap.get(rootId);
        return root;
    }

    /**
     *
     * @param node node
     * @return json
     */
    public JSONObject constructJS(Node node) {
        JSONObject jsonObject = new JSONObject();
        ArrayList<JSONObject> children = new ArrayList<>();
        for (Node child: node.getChildren()) {
            children.add(this.constructJS(child));
        }
        jsonObject.put("children", children);
        jsonObject.put("id", node.getId());
        jsonObject.put("name", node.getName());
        return jsonObject;
    }

    /**
     *
     * @param data data
     * @return jason
     */
    public JSONObject method(ArrayList<DirectoryAssetsDto> data) {
        Node root = this.constructLinks(data);
        return this.constructJS(root);
    }
}