java TreeUtil菜单递归工具类

package com.admin.manager.storeService.util;

import com.admin.manager.storeService.entity.Menu;

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

/**
 * @author m
 * @date 2019/12/16
 */
public class TreeUtil {

 /**
 * 获取菜单树
 * @param menus 所有菜单
 * @return
 */
 public static List<Menu> menuTree(List<Menu> menus) {
 //返回的菜单树
 List<Menu> rootMenus = new ArrayList<>();
 for (Menu menu : menus) {
  //pid（上级Id）为0的是根菜单
  if ("0".equals(menu.getPid())) {
  rootMenus.add(menu);
  }
 }
 //遍历，找到二级菜单（根菜单的id和所有菜单中的pid比较）
 for (Menu rootMenu : rootMenus) {
  List<Menu> child = getChild(String.valueOf(rootMenu.getId()), menus);
  rootMenu.setChildren(child);
 }
 return rootMenus;
 }


 /**
 * 递归获取下级菜单
 * @param pid 上级Id
 * @param menus 所有菜单
 * @return
 */
 public static List<Menu> getChild(String pid, List<Menu> menus) {
 //子菜单列表
 List<Menu> childList = new ArrayList<>();
 for (Menu menu : menus) {
  if (pid.equals(menu.getPid())) {
  childList.add(menu);
  }
 }
 //遍历 递归获取子菜单的子菜单
 for (Menu menu : childList) {
  List<Menu> child = getChild(String.valueOf(menu.getId()), menus);
  menu.setChildren(child);
 }
 //递归出口 childList长度为0
 if (childList.size() == 0) {
  return new ArrayList<>();
 }
 return childList;
 }
}

import com.energy.service.vo.RegionTree;

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

/**
 * @author m
 * @date 2020/4/2
 */
public class TreeUtil {
 /**
 * 创建树结构
 * @param regionTrees
 * @return
 */
 private List<RegionTree> tree(List<RegionTree> regionTrees) {
 //返回的节点树
 List<RegionTree> rootNodes = new ArrayList<>();
 Iterator<RegionTree> it = regionTrees.iterator();
 while (it.hasNext()) {
  RegionTree next = it.next();
  //parent（上级Id）为0的是根节点
  if ("0".equals(next.getParentId())) {
  rootNodes.add(next);
  it.remove();
  }
 }
 //遍历，找到二级节点
 for (RegionTree regionTree : rootNodes) {
  List<RegionTree> child = getChild(regionTrees, regionTree.getId().toString());
  regionTree.setChildren(child);
 }
 return rootNodes;

 }

 /**
 * 查子节点
 *
 * @param regions
 * @param parentId
 * @return
 */
 private List<RegionTree> getChild(List<RegionTree> regions, String parentId) {

 //子节点列表
 List<RegionTree> childList = new ArrayList<>();
 Iterator<RegionTree> it = regions.iterator();
 while (it.hasNext()) {
  RegionTree regionTree = it.next();
  if (parentId.equals(regionTree.getParentId())) {
  childList.add(regionTree);
  it.remove();
  }
 }

 //遍历 递归获取子节点的子节点
 for (RegionTree regionTree : childList) {
  List<RegionTree> child = getChild(regions, regionTree.getId().toString());
  regionTree.setChildren(child);
 }
 //递归出口 childList长度为0
 if (childList.size() == 0) {
  return new ArrayList<>();
 }
 return childList;
 }
}