我有一个字符串,我想用它作为文件名,所以我想用Python删除文件名中不允许的所有字符。

我宁愿严格一点,所以假设我想只保留字母、数字和一小组其他字符,如“_-.()”。”。最优雅的解决方案是什么?

文件名需要在多个操作系统(Windows, Linux和Mac OS)上有效——它是我库中的一个MP3文件,以歌曲标题为文件名,并在3台机器之间共享和备份。


当前回答

我相信这不是一个很好的答案,因为它修改了它循环的字符串,但它似乎工作得很好:

import string
for chr in your_string:
 if chr == ' ':
   your_string = your_string.replace(' ', '_')
 elif chr not in string.ascii_letters or chr not in string.digits:
    your_string = your_string.replace(chr, '')

其他回答

更新

在这个6年的答案中,所有的链接都无法修复。

同样,我也不会再这样做了,只是base64编码或删除不安全的字符。Python 3示例:

import re
t = re.compile("[a-zA-Z0-9.,_-]")
unsafe = "abc∂éåß®∆˚˙©¬ñ√ƒµ©∆∫ø"
safe = [ch for ch in unsafe if t.match(ch)]
# => 'abc'

使用base64可以进行编码和解码,因此可以再次检索原始文件名。

但是根据用例,最好生成一个随机文件名并将元数据存储在单独的文件或DB中。

from random import choice
from string import ascii_lowercase, ascii_uppercase, digits
allowed_chr = ascii_lowercase + ascii_uppercase + digits

safe = ''.join([choice(allowed_chr) for _ in range(16)])
# => 'CYQ4JDKE9JfcRzAZ'

原文链接:

bobcat项目包含了一个python模块来完成这个任务。

它不是完全健壮的,看看这篇文章和这个回复。

因此,如前所述:如果可读性不重要,base64编码可能是一个更好的主意。

文档https://svn.origo.ethz.ch/bobcat/src-doc/safefilename-module.html 源https://svn.origo.ethz.ch/bobcat/trunk/src/bobcatlib/safefilename.py

不过你得小心点。如果你只看拉丁语言,在你的介绍中没有清楚地说出来。如果您仅使用ascii字符对某些单词进行消毒,它们可能会变得毫无意义或具有其他含义。

假设你有“forêt poésie”(森林诗歌),你的消毒可能会给“堡垒-posie”(强大+无意义的东西)

如果你必须处理汉字,那就更糟了。

“下北沢”您的系统可能最终会执行“——”,这注定会在一段时间后失败,而且没有多大帮助。因此,如果您只处理文件,我建议您将它们称为您控制的通用链,或者保持字符原样。对于uri,大致相同。

This whitelist approach (ie, allowing only the chars present in valid_chars) will work if there aren't limits on the formatting of the files or combination of valid chars that are illegal (like ".."), for example, what you say would allow a filename named " . txt" which I think is not valid on Windows. As this is the most simple approach I'd try to remove whitespace from the valid_chars and prepend a known valid string in case of error, any other approach will have to know about what is allowed where to cope with Windows file naming limitations and thus be a lot more complex.

>>> import string
>>> valid_chars = "-_.() %s%s" % (string.ascii_letters, string.digits)
>>> valid_chars
'-_.() abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
>>> filename = "This Is a (valid) - filename%$&$ .txt"
>>> ''.join(c for c in filename if c in valid_chars)
'This Is a (valid) - filename .txt'

这是Windows特定路径的另一个答案,使用简单的替换,没有时髦的模块:

import re

def check_for_illegal_char(input_str):
    # remove illegal characters for Windows file names/paths 
    # (illegal filenames are a superset (41) of the illegal path names (36))
    # this is according to windows blacklist obtained with Powershell
    # from: https://stackoverflow.com/questions/1976007/what-characters-are-forbidden-in-windows-and-linux-directory-names/44750843#44750843
    #
    # PS> $enc = [system.Text.Encoding]::UTF8
    # PS> $FileNameInvalidChars = [System.IO.Path]::GetInvalidFileNameChars()
    # PS> $FileNameInvalidChars | foreach { $enc.GetBytes($_) } | Out-File -FilePath InvalidFileCharCodes.txt

    illegal = '\u0022\u003c\u003e\u007c\u0000\u0001\u0002\u0003\u0004\u0005\u0006\u0007\u0008' + \
              '\u0009\u000a\u000b\u000c\u000d\u000e\u000f\u0010\u0011\u0012\u0013\u0014\u0015' + \
              '\u0016\u0017\u0018\u0019\u001a\u001b\u001c\u001d\u001e\u001f\u003a\u002a\u003f\u005c\u002f' 

    output_str, _ = re.subn('['+illegal+']','_', input_str)
    output_str = output_str.replace('\\','_')   # backslash cannot be handled by regex
    output_str = output_str.replace('..','_')   # double dots are illegal too, or at least a bad idea 
    output_str = output_str[:-1] if output_str[-1] == '.' else output_str # can't have end of line '.'

    if output_str != input_str:
        print(f"The name '{input_str}' had invalid characters, "
              f"name was modified to '{output_str}'")

    return output_str

当测试check_for_illegal_char('fas\u0003\u0004good\\..asd.'),我得到:

The name 'fas♥♦good\..asd.' had invalid characters, name was modified to 'fas__good__asd'

给,这应该涵盖了所有的基础。它为您处理所有类型的问题,包括(但不限于)字符替换。

适用于Windows、*nix和几乎所有其他文件系统。只允许打印字符。

def txt2filename(txt, chr_set='normal'):
    """Converts txt to a valid Windows/*nix filename with printable characters only.

    args:
        txt: The str to convert.
        chr_set: 'normal', 'universal', or 'inclusive'.
            'universal':    ' -.0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
            'normal':       Every printable character exept those disallowed on Windows/*nix.
            'extended':     All 'normal' characters plus the extended character ASCII codes 128-255
    """

    FILLER = '-'

    # Step 1: Remove excluded characters.
    if chr_set == 'universal':
        # Lookups in a set are O(n) vs O(n * x) for a str.
        printables = set(' -.0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz')
    else:
        if chr_set == 'normal':
            max_chr = 127
        elif chr_set == 'extended':
            max_chr = 256
        else:
            raise ValueError(f'The chr_set argument may be normal, extended or universal; not {chr_set=}')
        EXCLUDED_CHRS = set(r'<>:"/\|?*')               # Illegal characters in Windows filenames.
        EXCLUDED_CHRS.update(chr(127))                  # DEL (non-printable).
        printables = set(chr(x)
                         for x in range(32, max_chr)
                         if chr(x) not in EXCLUDED_CHRS)
    result = ''.join(x if x in printables else FILLER   # Allow printable characters only.
                     for x in txt)

    # Step 2: Device names, '.', and '..' are invalid filenames in Windows.
    DEVICE_NAMES = 'CON,PRN,AUX,NUL,COM1,COM2,COM3,COM4,' \
                   'COM5,COM6,COM7,COM8,COM9,LPT1,LPT2,' \
                   'LPT3,LPT4,LPT5,LPT6,LPT7,LPT8,LPT9,' \
                   'CONIN$,CONOUT$,..,.'.split()        # This list is an O(n) operation.
    if result in DEVICE_NAMES:
        result = f'-{result}-'

    # Step 3: Maximum length of filename is 255 bytes in Windows and Linux (other *nix flavors may allow longer names).
    result = result[:255]

    # Step 4: Windows does not allow filenames to end with '.' or ' ' or begin with ' '.
    result = re.sub(r'^[. ]', FILLER, result)
    result = re.sub(r' $', FILLER, result)

    return result

这个解决方案不需要外部库。它也替代了不可打印的文件名,因为它们并不总是容易处理。