java tree结构数据 转换为普通集合 并排序

    public List<HeaderManagerVO> flattenList(List<HeaderManagerVO> treeList) {
        List<HeaderManagerVO> flatList = new ArrayList<>();
        int a=1;
        for (HeaderManagerVO node : treeList) {
            node.setOrderNum(a++);
            flatList.add(node);
            if (node.getChildren() != null && ! node.getChildren().isEmpty()) {
                flatList.addAll(flattenList(node.getChildren()));
            }
        }
        return flatList;
    }