在Python 2.5中解码未知的unicoding编码的最佳方法

Question

我有没有正确的方法？无论如何,我正在解析很多HTML,但我并不总是知道它的编码是什么(一个令人惊讶的数字谎言).下面的代码很容易显示到目前为止我一直在做的事情,但我确信有更好的方法.非常感谢您的建议.

import logging
import codecs
from utils.error import Error

class UnicodingError(Error):
    pass

# these encodings should be in most likely order to save time
encodings = [ "ascii", "utf_8", "big5", "big5hkscs", "cp037", "cp424", "cp437", "cp500", "cp737", "cp775", "cp850", "cp852", "cp855", 
    "cp856", "cp857", "cp860", "cp861", "cp862", "cp863", "cp864", "cp865", "cp866", "cp869", "cp874", "cp875", "cp932", "cp949", 
    "cp950", "cp1006", "cp1026", "cp1140", "cp1250", "cp1251", "cp1252", "cp1253", "cp1254", "cp1255", "cp1256", "cp1257", "cp1258", 
    "euc_jp", "euc_jis_2004", "euc_jisx0213", "euc_kr", "gb2312", "gbk", "gb18030", "hz", "iso2022_jp", "iso2022_jp_1", "iso2022_jp_2", 
    "iso2022_jp_2004", "iso2022_jp_3", "iso2022_jp_ext", "iso2022_kr", "latin_1", "iso8859_2", "iso8859_3", "iso8859_4", "iso8859_5", 
    "iso8859_6", "iso8859_7", "iso8859_8", "iso8859_9", "iso8859_10", "iso8859_13", "iso8859_14", "iso8859_15", "johab", "koi8_r", "koi8_u", 
    "mac_cyrillic", "mac_greek", "mac_iceland", "mac_latin2", "mac_roman", "mac_turkish", "ptcp154", "shift_jis", "shift_jis_2004", 
    "shift_jisx0213", "utf_32", "utf_32_be", "utf_32_le", "utf_16", "utf_16_be", "utf_16_le", "utf_7", "utf_8_sig" ]

def unicode(string):
    '''make unicode'''
    for enc in self.encodings:
        try:
            logging.debug("unicoder is trying " + enc + " encoding")
            utf8 = unicode(string, enc)
            logging.info("unicoder is using " + enc + " encoding")
            return utf8
        except UnicodingError:
            if enc == self.encodings[-1]:
                raise UnicodingError("still don't recognise encoding after trying do guess.")

Answer 1

有两个用于检测未知编码的通用库:

• chardet,Universal Feed Parser的一部分
• UnicodeDammit,Beautiful Soup的一部分

chardet应该是firefox做它的方式的端口

您可以使用以下正则表达式从字节字符串中检测utf8:

import re

utf8_detector = re.compile(r"""^(?:
     [\x09\x0A\x0D\x20-\x7E]            # ASCII
   | [\xC2-\xDF][\x80-\xBF]             # non-overlong 2-byte
   |  \xE0[\xA0-\xBF][\x80-\xBF]        # excluding overlongs
   | [\xE1-\xEC\xEE\xEF][\x80-\xBF]{2}  # straight 3-byte
   |  \xED[\x80-\x9F][\x80-\xBF]        # excluding surrogates
   |  \xF0[\x90-\xBF][\x80-\xBF]{2}     # planes 1-3
   | [\xF1-\xF3][\x80-\xBF]{3}          # planes 4-15
   |  \xF4[\x80-\x8F][\x80-\xBF]{2}     # plane 16
  )*$""", re.X)

在实践中,如果你正在处理英语,我发现以下工作99.9%的时间:

1. 如果它通过上面的正则表达式,它是ascii或utf8
2. 如果它包含来自0x80-0x9f但不包含0xa4的任何字节,则它是Windows-1252
3. 如果它包含0xa4,则假设它是拉丁语-15
4. 否则假设它是拉丁语-1