Convert UTF-8 with BOM to UTF-8 with no BOM in Python

问题:

Two questions here. I have a set of files which are usually UTF-8 with BOM. I'd like to convert them (ideally in place) to UTF-8 with no BOM. It seems like codecs.StreamRecoder(stream, encode, decode, Reader, Writer, errors) would handle this. But I don't really see any good examples on usage. Would this be the best way to handle this?

source files: Tue Jan 17$ file brh-m-157.json  brh-m-157.json: UTF-8 Unicode (with BOM) text 

Also, it would be ideal if we could handle different input encoding wihtout explicitly knowing (seen ASCII and UTF-16). It seems like this should all be feasible. Is there a solution that can take any known Python encoding and output as UTF-8 without BOM?

edit 1 proposed sol'n from below (thanks!)

fp = open('brh-m-157.json','rw') s = fp.read() u = s.decode('utf-8-sig') s = u.encode('utf-8') print fp.encoding   fp.write(s) 

This gives me the following error:

IOError: [Errno 9] Bad file descriptor 

Newsflash

I'm being told in comments that the mistake is I open the file with mode 'rw' instead of 'r+'/'r+b', so I should eventually re-edit my question and remove the solved part.

回答1:

Simply use the "utf-8-sig" codec:

fp = open("file.txt") s = fp.read() u = s.decode("utf-8-sig") 

That gives you a unicode string without the BOM. You can then use

s = u.encode("utf-8") 

to get a normal UTF-8 encoded string back in s. If your files are big, then you should avoid reading them all into memory. The BOM is simply three bytes at the beginning of the file, so you can use this code to strip them out of the file:

import os, sys, codecs  BUFSIZE = 4096 BOMLEN = len(codecs.BOM_UTF8)  path = sys.argv[1] with open(path, "r+b") as fp:     chunk = fp.read(BUFSIZE)     if chunk.startswith(codecs.BOM_UTF8):         i = 0         chunk = chunk[BOMLEN:]         while chunk:             fp.seek(i)             fp.write(chunk)             i += len(chunk)             fp.seek(BOMLEN, os.SEEK_CUR)             chunk = fp.read(BUFSIZE)         fp.seek(-BOMLEN, os.SEEK_CUR)         fp.truncate() 

It opens the file, reads a chunk, and writes it out to the file 3 bytes earlier than where it read it. The file is rewritten in-place. As easier solution is to write the shorter file to a new file like newtover's answer. That would be simpler, but use twice the disk space for a short period.

As for guessing the encoding, then you can just loop through the encoding from most to least specific:

def decode(s):     for encoding in "utf-8-sig", "utf-16":         try:             return s.decode(encoding)         except UnicodeDecodeError:             continue     return s.decode("latin-1") # will always work 

An UTF-16 encoded file wont decode as UTF-8, so we try with UTF-8 first. If that fails, then we try with UTF-16. Finally, we use Latin-1 ― this will always work since all 256 bytes are legal values in Latin-1. You may want to return None instead in this case since it's really a fallback and your code might want to handle this more carefully (if it can).

回答2:

In Python 3 it's quite easy: read the file and rewrite it with utf-8 encoding:

s = open(bom_file, mode='r', encoding='utf-8-sig').read() open(bom_file, mode='w', encoding='utf-8').write(s) 

回答3:

import codecs import shutil import sys  s = sys.stdin.read(3) if s != codecs.BOM_UTF8:     sys.stdout.write(s)  shutil.copyfileobj(sys.stdin, sys.stdout) 

回答4:

This is my implementation to convert any kind of encoding to UTF-8 without BOM and replacing windows enlines by universal format:

def utf8_converter(file_path, universal_endline=True):     '''     Convert any type of file to UTF-8 without BOM     and using universal endline by default.      Parameters     ----------     file_path : string, file path.     universal_endline : boolean (True),                         by default convert endlines to universal format.     '''      # Fix file path     file_path = os.path.realpath(os.path.expanduser(file_path))      # Read from file     file_open = open(file_path)     raw = file_open.read()     file_open.close()      # Decode     raw = raw.decode(chardet.detect(raw)['encoding'])     # Remove windows end line     if universal_endline:         raw = raw.replace('\r\n', '\n')     # Encode to UTF-8     raw = raw.encode('utf8')     # Remove BOM     if raw.startswith(codecs.BOM_UTF8):         raw = raw.replace(codecs.BOM_UTF8, '', 1)      # Write to file     file_open = open(file_path, 'w')     file_open.write(raw)     file_open.close()     return 0 

回答5:

You can use codecs.

import codecs content = open("test.txt",'r').read() filehandle.close() if content[:3] == codecs.BOM_UTF8 content = content[3:] print content.decode("utf-8") 

回答6:

I found this question because having trouble with configparser.ConfigParser().read(fp) when opening files with UTF8 BOM header.

For those who are looking for a solution to remove the header so that ConfigPhaser could open the config file instead of reporting an error of: File contains no section headers, please open the file like the following:

        configparser.ConfigParser().read(config_file_path, encoding="utf-8-sig") 

This could save you tons of effort by making the remove of the BOM header of the file unnecessary.

(I know this sounds unrelated, but hopefully this could help people struggling like me.)

文章来源: Convert UTF-8 with BOM to UTF-8 with no BOM in Python