Python如何将STR转换为unicode (version)

Question

这个字符串是邮件的主题。我通过imaplib得到这个字符串。此字符串的类型为"str"。

谢谢!

#-*- coding: utf-8 -*-
import imaplib
from email.parser import HeaderParser
conn = imaplib.IMAP4('imap.gmail.com')
conn.login('myuser', 'my_pass')
conn.select()
conn.search(None, 'ALL')  # returns a nice list of messages...
data = conn.fetch(1, '(BODY[HEADER])')
header_data = data[1][0][1]
parser = HeaderParser()
msg = parser.parsestr(header_data)
print repr(msg['subject'].decode('utf-8'))

结果:

u'=?UTF-8?B?V2VsY29tZSB0byBBdGxhc01haWw=?='

Answer 1

使用email.header包中的decode_header和make_header函数来处理标头，然后将标头对象转换为unicode:

from email.header import make_header, decode_header
header = make_header(decode_header(msg['subject']))
unicode_header = unicode(header)
print repr(unicode_header)  # prints: u'Welcome to AtlasMail'

Answer 2

电子邮件主题中非ascii字符的编码在RFC-1342 -中有描述如您所见，在本例中，您的utf-8字节是base64编码的。

所以，你可以这样做:

import base64, quopri
try:
    encoding, enc_type, subject = msg["subject"].split("?", 2)
except ValueError:
    subject = msg["subject"].decode("utf-8")
    enc_type = "N/A"
if enc_type == "B":
    subject = base64.decodestring(subject).decode(encoding.lower())
elif enc_type == "Q":
    subject = quopri.decodestring(subject).decode(encoding.lower())