# Function: OpenRead(file)

# A text file can be encoded using:
#   (1) The default operating system code page, Or
#   (2) utf8 with a BOM header
#
#  If a text file is encoded with utf8, and does not have a BOM header,
#  the user can manually add a BOM header to the text file
#  using a text editor such as notepad++, and rerun the python script,
#  otherwise the file is read as a codepage file with the 
#  invalid codepage characters removed

import sys
if int(sys.version[0]) != 3:
    print('Aborted: Python 3.x required')
    sys.exit(1)

def bomType(file):
    """
    returns file encoding string for open() function

    EXAMPLE:
        bom = bomtype(file)
        open(file, encoding=bom, errors='ignore')
    """

    f = open(file, 'rb')
    b = f.read(4)
    f.close()

    if (b[0:3] == b'\xef\xbb\xbf'):
        return "utf8"

    # Python automatically detects endianess if utf-16 bom is present
    # write endianess generally determined by endianess of CPU
    if ((b[0:2] == b'\xfe\xff') or (b[0:2] == b'\xff\xfe')):
        return "utf16"

    if ((b[0:5] == b'\xfe\xff\x00\x00') 
              or (b[0:5] == b'\x00\x00\xff\xfe')):
        return "utf32"

    # If BOM is not provided, then assume its the codepage
    #     used by your operating system
    return "cp1252"
    # For the United States its: cp1252


def OpenRead(file):
    bom = bomType(file)
    return open(file, 'r', encoding=bom, errors='ignore')


#######################
# Testing it
#######################
fout = open("myfile1.txt", "w", encoding="cp1252")
fout.write("* hi there (cp1252)")
fout.close()

fout = open("myfile2.txt", "w", encoding="utf8")
fout.write("\u2022 hi there (utf8)")
fout.close()

# this case is still treated like codepage cp1252
#   (User responsible for making sure that all utf8 files
#   have a BOM header)
fout = open("badboy.txt", "wb")
fout.write(b"hi there.  barf(\x81\x8D\x90\x9D)")
fout.close()

# Read Example file with Bom Detection
fin = OpenRead("myfile1.txt")
L = fin.readline()
print(L)
fin.close()

# Read Example file with Bom Detection
fin = OpenRead("myfile2.txt")
L =fin.readline() 
print(L) #requires QtConsole to view, Cmd.exe is cp1252
fin.close()

# Read CP1252 with a few undefined chars without barfing
fin = OpenRead("badboy.txt")
L =fin.readline() 
print(L)
fin.close()

# Check that bad characters are still in badboy codepage file
fin = open("badboy.txt", "rb")
fin.read(20)
fin.close()

一些编码策略，请取消评论品味:

#!/bin/bash
#
tmpfile=$1
echo '-- info about file file ........'
file -i $tmpfile
enca -g $tmpfile
echo 'recoding ........'
#iconv -f iso-8859-2 -t utf-8 back_test.xml > $tmpfile
#enca -x utf-8 $tmpfile
#enca -g $tmpfile
recode CP1250..UTF-8 $tmpfile

您可能希望通过以循环的形式打开并读取文件来检查编码…但是你可能需要先检查文件大小:

# PYTHON
encodings = ['utf-8', 'windows-1250', 'windows-1252'] # add more
for e in encodings:
    try:
        fh = codecs.open('file.txt', 'r', encoding=e)
        fh.readlines()
        fh.seek(0)
    except UnicodeDecodeError:
        print('got unicode error with %s , trying different encoding' % e)
    else:
        print('opening the file with encoding:  %s ' % e)
        break

另一种计算编码的方法是使用 的代码 文件命令)。有大量的 可用的Python绑定。

文件源树中的python绑定可作为 Python-magic(或python3-magic) debian软件包。它可以通过执行以下操作来确定文件的编码:

import magic

blob = open('unknown-file', 'rb').read()
m = magic.open(magic.MAGIC_MIME_ENCODING)
m.load()
encoding = m.buffer(blob)  # "utf-8" "us-ascii" etc

在pypi上有一个名称相同但不兼容的python-magic pip包，它也使用libmagic。它也可以得到编码，通过这样做:

import magic

blob = open('unknown-file', 'rb').read()
m = magic.Magic(mime_encoding=True)
encoding = m.from_buffer(blob)

你可以使用' python-magic package，它不会将整个文件加载到内存中:

import magic


def detect(
    file_path,
):
    return magic.Magic(
        mime_encoding=True,
    ).from_file(file_path)

输出是编码名称，例如:

iso - 8859 - 1 us - ascii utf - 8

在一般情况下，原则上不可能确定文本文件的编码。所以没有标准的Python库来帮你做这个。

如果您对文本文件有更具体的了解(例如，它是XML)，可能会有库函数。

这个网站有python代码识别ascii，编码bom和utf8 no bom: https://unicodebook.readthedocs.io/guess_encoding.html。将文件读入字节数组(data): http://www.codecodex.com/wiki/Read_a_file_into_a_byte_array。举个例子。我在osx。

#!/usr/bin/python                                                                                                  

import sys

def isUTF8(data):
    try:
        decoded = data.decode('UTF-8')
    except UnicodeDecodeError:
        return False
    else:
        for ch in decoded:
            if 0xD800 <= ord(ch) <= 0xDFFF:
                return False
        return True

def get_bytes_from_file(filename):
    return open(filename, "rb").read()

filename = sys.argv[1]
data = get_bytes_from_file(filename)
result = isUTF8(data)
print(result)


PS /Users/js> ./isutf8.py hi.txt                                                                                     
True