如何使用Python解码HTTrack生成的编码图片URL？

问题场景 #

使用HTTrack Website Copier下载完整网站后，提取图片src属性得到的是以下特殊格式的内容：

cid:httpsX3aX2fX2fcommonsX2emX2ewikimediaX2eorgX2fstaticX2fimagesX2fmobileX2fcopyrightX2fcommonswikiX2dwordmarkX2esvg
cid:httpsX3aX2fX2fuploadX2ewikimediaX2eorgX2fwikipediaX2fcommonsX2fthumbX2f6X2f6eX2fBursitisX5fElbowX5fWCX2eJPGX2f800pxX2dBursitisX5fElbowX5fWCX2eJPGX3f20070925222131
cid:httpsX3aX2fX2fuploadX2ewikimediaX2eorgX2fwikipediaX2fcommonsX2fthumbX2f6X2f62X2fPDX2diconX2esvgX2f64pxX2dPDX2diconX2esvgX2epng
cid:httpsX3aX2fX2fuploadX2ewikimediaX2eorgX2fwikipediaX2fcommonsX2fthumbX2f6X2f6eX2fBursitisX5fElbowX5fWCX2eJPGX2f120pxX2dBursitisX5fElbowX5fWCX2eJPGX3f20070925222131

尝试urllib.parse.unquote等常规URL解码方法无效，需要将这类格式转换为正常明文URL。

格式分析 #

这类字符串的规则是：

• 前缀为cid:，需要先移除
• URL中的特殊字符被替换为X加对应ASCII码的十六进制值（例如X3a对应:，X2f对应/，X2e对应.，X5f对应_）

解决方案代码 #

使用Python正则表达式匹配并替换编码部分，实现解码：

import re

def decode_cid_url(cid_str):
    # 移除开头的cid:前缀
    url_content = cid_str.lstrip('cid:')
    # 匹配X+两位十六进制字符，转换为对应ASCII字符
    decoded_url = re.sub(r'X([0-9a-fA-F]{2})', lambda match: chr(int(match.group(1), 16)), url_content)
    return decoded_url

# 测试示例
sample_urls = [
    "cid:httpsX3aX2fX2fcommonsX2emX2ewikimediaX2eorgX2fstaticX2fimagesX2fmobileX2fcopyrightX2fcommonswikiX2dwordmarkX2esvg",
    "cid:httpsX3aX2fX2fuploadX2ewikimediaX2eorgX2fwikipediaX2fcommonsX2fthumbX2f6X2f6eX2fBursitisX5fElbowX5fWCX2eJPGX2f800pxX2dBursitisX5fElbowX5fWCX2eJPGX3f20070925222131"
]

for url in sample_urls:
    print(decode_cid_url(url))

执行结果 #

运行上述代码后，会输出正常的明文URL：

https://commons.m.wikimedia.org/static/images/mobile/copyright/commonswiki/wordmark.svg
https://upload.wikimedia.org/wikipedia/commons/thumb/6/6e/Bursitis_Elbow_WC.JPG/800px-Bursitis_Elbow_WC.JPG?20070925222131

内容的提问来源于stack exchange，提问作者YoYoYo