Java构建树形菜单工具类,递归写法

模型定义,这里受Spring Security的UserService启发,给model设置接口.想要使用此工具类的话，实现此接口即可.

package xyz.yq56.easytool.abs;

import java.util.List;


public interface TreeNode {

    
    String getId();

    
    String getPid();

    
     List getChildren();

    
     void setChildren(List children);

}

工具类源码:

package xyz.yq56.easytool.utils.recursion;

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

import xyz.yq56.easytool.abs.TreeNode;
import xyz.yq56.easytool.utils.collection.CollectUtil;


public class RecursionUtil {

    private RecursionUtil() {}

    
    public static  void buildTree(List list, T node) {
        if (CollectUtil.isEmpty(list)) {
            return;
        }
        List children = new ArrayList<>();
        for (T menu : list) {
            if (Objects.equals(menu.getPid(), node.getId())) {
                children.add(menu);
                buildTree(getRemainList(list, menu.getPid()), menu);
            }
        }
        if(!CollectUtil.isEmpty(children)){
            node.setChildren(children);
        }

    }

    
    private static  List getRemainList(List list, String pid) {
        return CollectUtil.filter(list,item -> !Objects.equals(item.getPid(), pid));
    }
}

实现TreeNode接口

package xyz.yq56.sm.module.menu.model;

import java.util.List;

import lombok.Data;
import xyz.yq56.easytool.abs.TreeNode;


@Data
public class MenuVo implements TreeNode {

  private String id;

  private String pid;

  private String name;

  private String path;

  private String icon;

  private List children;

  @Override
  public  void setChildren(List list) {
      this.children = (List) list;
  }
}

service层代码: 直接使用RecursionUtil.buildTree方法即可

package xyz.yq56.sm.module.menu.service.impl;

import java.util.List;

import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import xyz.yq56.easytool.utils.collection.CollectUtil;
import xyz.yq56.easytool.utils.nvll.NullUtil;
import xyz.yq56.easytool.utils.recursion.RecursionUtil;
import xyz.yq56.sm.module.menu.model.Menu;
import xyz.yq56.sm.module.menu.model.MenuVo;
import xyz.yq56.sm.module.menu.service.MenuBizService;
import xyz.yq56.sm.module.menu.service.MenuService;


@Service
public class MenuBizServiceImpl implements MenuBizService {

    @Autowired
    private MenuService menuService;

    @Override
    public MenuVo getMenu(String pid) {
    	//拿到菜单原始数据
        List list = menuService.list();
        //拿到菜单原始数据,转化为vo集合
        List menuVoList = CollectUtil.mapToOtherList(list, item -> {
            MenuVo menuVo = new MenuVo();
            BeanUtils.copyProperties(item, menuVo);
            return menuVo;
        });
        //如果指定了特定节点，那么特定节点为根节点，没有的话就默认null的是根节点
        Menu byId = menuService.getById(pid);
        MenuVo menuVo = new MenuVo();
        NullUtil.apply(byId, item -> {
            BeanUtils.copyProperties(item, menuVo);
            return null;
        });

		//构建以menuVo为根节点的树形结构
        RecursionUtil.buildTree(menuVoList, menuVo);
        return menuVo;
    }

}

controller

@RestController
@RequestMapping("/menu/biz/")
public class MenuBizController {

    @Autowired
    MenuBizService menuBizService;

    @GetMapping("getMenu")
    public MenuVo getMenu(String pid) {
        return menuBizService.getMenu(pid);
    }

}

请求效果

不指定特定节点时，以null为根节点.日常使用,可以直接拿根节点的children作为菜单也可.

http://localhost:8080/menu/biz/getMenu

{
    "code": 200,
    "data": {
        "id": null,
        "pid": null,
        "name": null,
        "path": null,
        "icon": null,
        "children": [
            {
                "id": "1445371079417503745",
                "pid": null,
                "name": "用户管理",
                "path": "/user",
                "icon": "el-icon-user",
                "children": [
                    {
                        "id": "1445372598120456194",
                        "pid": "1445371079417503745",
                        "name": "用户信息",
                        "path": "/user_info",
                        "icon": "el-icon-s-custom",
                        "children": null
                    },
                    {
                        "id": "1445405355609530370",
                        "pid": "1445371079417503745",
                        "name": "用户列表",
                        "path": "/users",
                        "icon": "el-icon-s-custom",
                        "children": null
                    }
                ]
            },
            {
                "id": "1445372340355309569",
                "pid": null,
                "name": "菜单管理",
                "path": "/menu",
                "icon": "el-icon-menu",
                "children": null
            }
        ]
    },
    "msg": "success",
    "date": "2021-10-05T17:38:36.153+00:00"
}

指定特定节点.比如我只想取以上用户管理的菜单,那么拿到用户管理的id传入即可.

http://localhost:8080/menu/biz/getMenu?pid=1445371079417503745

{
    "code": 200,
    "data": {
        "id": "1445371079417503745",
        "pid": null,
        "name": "用户管理",
        "path": "/user",
        "icon": "el-icon-user",
        "children": [
            {
                "id": "1445372598120456194",
                "pid": "1445371079417503745",
                "name": "用户信息",
                "path": "/user_info",
                "icon": "el-icon-s-custom",
                "children": null
            },
            {
                "id": "1445405355609530370",
                "pid": "1445371079417503745",
                "name": "用户列表",
                "path": "/users",
                "icon": "el-icon-s-custom",
                "children": null
            }
        ]
    },
    "msg": "success",
    "date": "2021-10-05T17:41:30.870+00:00"
}

数据库原始数据

前端展示(Vue)

不知道怎么构建树形菜单的小伙伴可以看下这个工具类,希望可以给一部分朋友一点启示.有帮助的话，请点赞或评论，谢谢