递归demo

/**
 * 叶子节点集朝上遍历
 * @param leafAto
 * @return
 */
private List<Long> getParentNodeId(Unit leaf) {
    List<Long> parentNodeIdList= new ArrayList<>();
  if (leaf== null) {
        return parentNodeBuIdList;
    } else if (leaf.getParentId() == null) {
        parentNodeIdList.add(leaf.getParentId());
        return parentNodeBuIdList;
    } else {
        parentNodeIdList.add(leaf.getParentId());
        parentNodeIdList.addAll(getParentNodeId(getById(leaf.getParentId())));
    }
    return parentNodeBuIdList;
}