一个SQL查询出所有数据--后台递归组tree数据结构

public List<CategoryEntity> listWithTree() {
        //1、查出所有分类
        List<CategoryEntity> entities = baseMapper.selectList(null);

        //2、找到所有的一级分类
        List<CategoryEntity> level1Menus = entities.stream().filter(categoryEntity ->
             categoryEntity.getParentCid() == 0
        ).map((menu)->{
　　　　　// 这里可以对数据进行逻辑处理
            menu.setChildren(getChildrens(menu,entities));
            return menu;
        }).sorted((menu1,menu2)->{
            return (menu1.getSort()==null?0:menu1.getSort()) - (menu2.getSort()==null?0:menu2.getSort());
        }).collect(Collectors.toList());

        return level1Menus;
    }

//递归查找所有菜单的子菜单
    private List<CategoryEntity> getChildrens(CategoryEntity root,List<CategoryEntity> all){

        List<CategoryEntity> children = all.stream().filter(categoryEntity -> {
            return categoryEntity.getParentCid() == root.getCatId();
        }).map(categoryEntity -> {
            //1、找到子菜单
            categoryEntity.setChildren(getChildrens(categoryEntity,all));
            return categoryEntity;
        }).sorted((menu1,menu2)->{
            //2、菜单的排序
            return (menu1.getSort()==null?0:menu1.getSort()) - (menu2.getSort()==null?0:menu2.getSort());
        }).collect(Collectors.toList());

        return children;
    }