权限菜单数据无限级遍历返回json结构数据，我这里整理2种方法，一种循环方式的，一种递归方式的

循环方式遍历

        @Test
	public void test2(){

	    Long time1 = System.currentTimeMillis();

		Map map1 = new HashMap();
		map1.put("id",1);
		map1.put("pid","");

		Map map2 = new HashMap();
		map2.put("id",2);
		map2.put("pid",1);
		Map map21 = new HashMap();
		map21.put("id",21);
		map21.put("pid",1);

		Map map3 = new HashMap();
		map3.put("id",3);
		map3.put("pid","");

		Map map4 = new HashMap();
		map4.put("id",4);
		map4.put("pid",2);

		Map map5 = new HashMap();
		map5.put("id",5);
		map5.put("pid",4);
		Map map6 = new HashMap();
		map6.put("id",6);
		map6.put("pid",3);
		Map map7 = new HashMap();
		map7.put("id",7);
		map7.put("pid","");

		List<Map> list = new ArrayList<>();
		list.add(map1);
		list.add(map2);
		list.add(map21);
		list.add(map3);
		list.add(map4);
		list.add(map5);
		list.add(map6);
		list.add(map7);

		//取得数据
		List<Map> resultMap = list;
		//定义一个Map集合 存储按指定顺序排列好的菜单
		Map<String, List<Map<Object,Object>>> temp = new HashMap<String, List<Map<Object,Object>>>();

		for (Map map : resultMap) {
			//如果temp的键包含这个parentid
			if(temp.containsKey(map.get("pid").toString())){
				//那么把所有相同parentid的数据全部添加到该parentid键下
				temp.get(map.get("pid").toString()).add(map);
			}else{
				//初始化temp  第一次用
				List<Map<Object,Object>> lists = new ArrayList<Map<Object,Object>>();
				lists.add(map);
				temp.put(map.get("pid").toString(), lists);
			}
		}

		//定义一个完整菜单列表
		ArrayList<Map<Object,Object>> array = new ArrayList<Map<Object,Object>>();
		for (Map hashMap : resultMap) {
			//如果temp中的键与当前id一致
			if(temp.containsKey(hashMap.get("id").toString())){
				//说明temp是当前id菜单的子菜单
				hashMap.put("children", temp.get(hashMap.get("id").toString()));
			}
			//遇到顶级菜单就添加进完整菜单列表
			if("".equals(hashMap.get("pid"))){
				array.add(hashMap);
			}

		}

		System.out.println(JSON.toJSONString(array));

		Long time2 = System.currentTimeMillis();

        System.out.println(time2-time1);

	}

递归方式遍历

	@Test
	public void test3(){
	    Long time1 = System.currentTimeMillis();

		Map map1 = new HashMap();
		map1.put("id",1);
		map1.put("pid","");

		Map map2 = new HashMap();
		map2.put("id",2);
		map2.put("pid",1);
		Map map21 = new HashMap();
		map21.put("id",21);
		map21.put("pid",1);

		Map map3 = new HashMap();
		map3.put("id",3);
		map3.put("pid","");

		Map map4 = new HashMap();
		map4.put("id",4);
		map4.put("pid",2);

		Map map5 = new HashMap();
		map5.put("id",5);
		map5.put("pid",4);
		Map map6 = new HashMap();
		map6.put("id",6);
		map6.put("pid",3);
		Map map7 = new HashMap();
		map7.put("id",7);
		map7.put("pid","");

		List<Map> list = new ArrayList<>();
		list.add(map1);
		list.add(map2);
		list.add(map21);
		list.add(map3);
		list.add(map4);
		list.add(map5);
		list.add(map6);
		list.add(map7);

		List<Map> treeMenuList = this.treeMenuList(list,"");
		System.out.println(JSON.toJSONString(treeMenuList));

		Long time2 = System.currentTimeMillis();

        System.out.println(time2-time1);

	}

	public List<Map> treeMenuList(List<Map> menuList, String parentId) {
		List<Map> childMenu = new ArrayList<>();
		for (Map jsonMenu : menuList) {
			String menuId = jsonMenu.get("id")+"";
			String pid = jsonMenu.get("pid")+"";
			if (parentId.equals(pid)) {
				List<Map> c_node = treeMenuList(menuList, menuId);
				if (c_node.size()>0){
					jsonMenu.put("childNode", c_node);
				}
				childMenu.add(jsonMenu);
			}
		}
		return childMenu;
	}

经过测试，循环的速度更快，递归的稍慢一些