pyhton 判断文件 或 目录是否存在

判断目录是否为：目录：

os.path.isdir(path)
Return True if path is an existing directory. This follows symbolic links, so both islink() and
isdir() can be true for the same path.

判断目录是否为：文件：

os.path.isfile(path)
Return True if path is an existing regular file. This follows symbolic links, so both islink() and
isfile() can be true for the same path.

判断目录是否为：符号链接：

os.path.islink(path)
Return True if path refers to a directory entry that is a symbolic link. Always False if symbolic links are
not supported.