根据子节点递归查询所有父节点

有个需求,需要根据给定的子节点向上递归查询所有父节点,网上查找了一些,但是都不是很满意,有的是需要用到全局变量定义存储列表,但是会有并发问题,然后自己手写一个

 @Test
    void contextLoads1() {

        List<School> list = new ArrayList<School>();
        list.add(new School(1,"张三丰",0));
        list.add(new School(2,"张无忌",1));
        list.add(new School(3,"张翠山",2));
        list.add(new School(4,"殷梨亭",3));
        list.add(new School(5,"俞莲舟",3));
        list.add(new School(6,"宋远桥",4));
        list.add(new School(7,"宋远桥",5));

        List<Integer> idList = new ArrayList<>();
        //以id为6的对象为例,他的父节点是4,先将本身的id设置进列表中
        idList.add(6);

        List<Integer> integerList = getpid(idList, 4, list);

        System.out.println(integerList);


    }

    public List<Integer> getpid(List<Integer> idList,Integer pid,List<School> schools){
        School school = schools.stream().filter(s -> s.getId() == pid).findFirst().get();
        idList.add(school.getId());
        if (school.getId() != 1){
            getpid(idList,school.getPid(),schools);
        }

        return  idList;
    }

结果为:

[6, 4, 3, 2, 1]

符合期望

,还有一种方法就是直接在数据库中写一个递归的函数,这也是可行的,

BEGIN
	DECLARE idStr VARCHAR(2048);
	DECLARE childIdStr VARCHAR(2048);
	SET idStr = '$';
	SET childIdStr = CAST(orgId AS CHAR);
	WHILE childIdStr IS NOT NULL DO
		SET idStr = CONCAT(idStr, ',', childIdStr);
		SELECT GROUP_CONCAT(pid) INTO childIdStr FROM school WHERE FIND_IN_SET(id, childIdStr) > 0;
	END WHILE;
	RETURN idStr;
END

函数名以及传入和返回参数:

fc_queryParentDeviceTypeId

返回的是这样的结果

$,6,4,3,2,1

 后续可以自己处理