def list_dir(path = None):
    dir_list = os.listdir(path)
    for cur_file in dir_list:
        cur_path = os.path.join(path, cur_file)
        if os.path.isfile(cur_path):
            print ("{0} : is file!".format(cur_path))
        elif os.path.isdir(cur_path):
            print("{0} : is dir!".format(cur_path))
            list_dir(cur_path) # 递归子目录