Java开发树结构数据封装！

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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 {@Resourceprivate UserInfoDao userInfoDao;@Overridepublic List<MenuTreeVo> findGetInfoByUserId(Long userId) {return userInfoDao.findGetInfoByUserId(userId);}/*** 查询树结构菜单* @return 返回树结构菜单*/@Overridepublic 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:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- mapper是映射文件的根标签 namespace属性 指定mapper映射对应的mapper接口是谁 -->
<mapper namespace="com.ekgc.qy.dao.UserInfoDao"><!--    id：重写的方法；
resultType：返回值类型。pojo实体类
resultMap 对应返回值类型需要手动指定
parameterType:对应方法参数类型
--><!--    列表一对多嵌套--><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><!--    colection1对多查询--><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 smLEFT JOIN sys_role_menu srm ON sm.id = srm.menu_idLEFT JOIN sys_role sr ON srm.role_id = sr.idLEFT JOIN sys_user su ON su.user_type = sr.idWHERE 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 smLEFT JOIN sys_role_menu srm ON sm.id = srm.menu_idLEFT JOIN sys_role sr ON srm.role_id = sr.idLEFT JOIN sys_user su ON su.user_type = sr.idWHERE 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;
}