Java开发树结构数据封装！

---

源数据如下

controller接口：

@RequestMapping("/UserTreeInfo")
    public RespBody getUserTreeInfo(Long userId) {
        List<MenuTreeVo> userInfo = userInfoServiceimpl.getUserTreeInfo(userId);
        if (userInfo != null && userInfo.size() > 0) {
            return new RespBody(200,userInfo,"查询成功");
        }
        return new RespBody(501,null,"查询失败");
    }

service层封装:

package com.ekgc.qy.Service.impl;

import com.ekgc.qy.Service.UserInfoService;
import com.ekgc.qy.dao.UserInfoDao;
import com.ekgc.qy.pojo.dto.MenuDto;
import com.ekgc.qy.pojo.vo.MenuTreeVo;
import jakarta.annotation.Resource;
import org.apache.commons.beanutils.BeanUtils;
import org.springframework.stereotype.Service;

import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;

/**
 * @author Magic
 * @version 1.0
 */
@Service
public class UserInfoServiceimpl implements UserInfoService {
    @Resource
    private UserInfoDao userInfoDao;

    @Override
    public List<MenuTreeVo> findGetInfoByUserId(Long userId) {
        return userInfoDao.findGetInfoByUserId(userId);
    }

    /**
     * 查询树结构菜单
     * @return 返回树结构菜单
     */
    @Override
    public List<MenuTreeVo> getUserTreeInfo(Long userId) {
        //查出所有菜单和目录
        List<MenuDto> userTreeInfo = userInfoDao.getUserTreeInfo(userId);
        // 先过滤出所有的父菜单目录
        List<MenuDto> mulu = userTreeInfo
                .stream()
                .filter(ml -> ml.getParentId() == 0).toList();
        return buildTrees(mulu,userTreeInfo);
    }

    private ArrayList<MenuTreeVo> buildTrees(List<MenuDto> data, List<MenuDto> menus) {
        // 存储树结构的菜单树
        ArrayList<MenuTreeVo> trees = new ArrayList<>();
        // 封装树结构菜单数据
        data.forEach(md -> {
            // 封装的MenuTreeVo树结构对象
             MenuTreeVo ml = new MenuTreeVo();
            // 根据属性名 将数据复制到另一个对象
            // 实现MenuDto到MenuTreeVo的转换
            try {
                BeanUtils.copyProperties(ml, md);//前一个是目标对象，后一个是源对象
            } catch (IllegalAccessException e) {
                throw new RuntimeException(e);
            } catch (InvocationTargetException e) {
                throw new RuntimeException(e);
            }


            //遍历目录和菜单找出子菜单并封装子菜单
            List<MenuDto> childs = new ArrayList<>();
            menus.forEach(m ->{
                if (m.getParentId() != null){
                    if (m.getParentId().equals(md.getId())){
                        childs.add(m);
                    }
                }
            });
            // 没有子菜单 不继续执行递归
            if (!childs.isEmpty()) {
                ml.setChildMenus(buildTrees(childs, menus));
            }
            trees.add(ml);
        });
        return trees;
    }
}

Dao接口：

package com.ekgc.qy.dao;

import com.ekgc.qy.pojo.dto.MenuDto;
import com.ekgc.qy.pojo.vo.MenuTreeVo;

import java.util.List;

/**
 * @author Magic
 * @version 1.0
 */
public interface UserInfoDao {
    List<MenuTreeVo> findGetInfoByUserId(Long userId);

    List<MenuDto> getUserTreeInfo(Long userId);

}

Dao层Mapper:

DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.ekgc.qy.dao.UserInfoDao">
    
    
    <resultMap id="roleMenus" type="MenuTreeVo">
        <id property="id" column="id"/>
        <result property="menuName" column="menu_name"/>
        <result property="permissions" column="permissions"/>
        <collection property="childMenus" ofType="MenuDto" javaType="java.util.ArrayList">
            <id property="id" column="childId"/>
            <result property="menuName" column="menuName"/>
            <result property="menuUrl" column="menuUrl"/>
            <result property="permissions" column="auth"/>
            <result property="path" column="path"/>
            <result property="parentId" column="parent_id"/>
        collection>
    resultMap>

    
    <select id="findGetInfoByUserId" resultMap="roleMenus">
        SELECT ml.id,ml.menu_name,ml.permissions,
               sy.id AS childId,sy.menu_name AS menuName,sy.menu_url AS menuUrl,sy.permissions AS auth,sy.path,sy.parent_id FROM sys_menu sy,
               (SELECT sm.id,menu_name,permissions FROM sys_menu sm
                LEFT JOIN sys_role_menu srm ON sm.id = srm.menu_id
                LEFT JOIN sys_role sr ON srm.role_id = sr.id
                LEFT JOIN sys_user su ON su.user_type = sr.id
                WHERE su.id = #{userId}) AS ml WHERE ml.id = sy.parent_id
    select>

    <select id="getUserTreeInfo" resultType="com.ekgc.qy.pojo.dto.MenuDto">
        SELECT sm.id,menu_name,menu_url,path,permissions,parent_id FROM sys_menu sm
        LEFT JOIN sys_role_menu srm ON sm.id = srm.menu_id
        LEFT JOIN sys_role sr ON srm.role_id = sr.id
        LEFT JOIN sys_user su ON su.user_type = sr.id
        WHERE su.id = #{userId} AND menu_name like concat("%",#{menuName},"%")
    select>
mapper>

映射实体类：

实体类只要有sql查询到的字段(id,menu_name,menu_url,path,permissions,parent_id)有就可以映射，不能缺少某个字段否则映射不了！

package com.ekgc.qy.pojo.vo;

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import java.util.ArrayList;

/**
 * @author Magic
 * @version 1.0
 */
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class MenuTreeVo {
    private Long id;
    private String menuName;
    private String menuUrl;
    private String permissions;
    private String path;
    private Long parentId;
    private ArrayList<MenuTreeVo> childMenus;
}