在url中使用中文其实是一个坏习惯，会带来一系列的转码问题， 我更喜欢英文译名或者id来标识某个uri。但是现实往往是残酷的， 特别是在我们调用别人服务时候，有时候被逼无奈使用中文URL。

Python中unicode转码一向是让人头疼的问题。数次碰壁之后，我也摸出了一些门道， 研读完Python字符串的encode与decode 之后，就自认为找到了万金油，谁知道这次又碰上这个老冤家。

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.6/urllib2.py", line 126, in urlopen
    return _opener.open(url, data, timeout)
  File "/usr/lib/python2.6/urllib2.py", line 391, in open
    response = self._open(req, data)
  File "/usr/lib/python2.6/urllib2.py", line 409, in _open
    '_open', req)
  File "/usr/lib/python2.6/urllib2.py", line 369, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.6/urllib2.py", line 1170, in http_open
    return self.do_open(httplib.HTTPConnection, req)
  File "/usr/lib/python2.6/urllib2.py", line 1142, in do_open
    h.request(req.get_method(), req.get_selector(), req.data, headers)
  File "/usr/lib/python2.6/httplib.py", line 914, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python2.6/httplib.py", line 951, in _send_request
    self.endheaders()
  File "/usr/lib/python2.6/httplib.py", line 908, in endheaders
    self._send_output()
  File "/usr/lib/python2.6/httplib.py", line 780, in _send_output
    self.send(msg)
  File "/usr/lib/python2.6/httplib.py", line 759, in send
    self.sock.sendall(str)
  File "<string>", line 1, in sendall
UnicodeEncodeError: 'ascii' codec can't encode characters in position 7-8: ordinal not in range(128)

这次错误引发是在 urlopen() 引起的，很有特色，开始使用 url.encode('utf-8') 就可以解决了。 今天我做了一些测试。

1. ascii + unicode 测试

>>> 'a' + u'b'
>>> '你' + u'好'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe4 in position 0: ordinal not in range(128)
>>> u'你' + u'好'
u'u4f60u597d'
>>> u'a' + '你' + u'好'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe4 in position 0: ordinal not in range(128)

上面的测试说明ascii码和unicode码相连操作，结论是有中文记得带上u，就不会有问题。 Python默认解码器是ascii，无法解码unicode中的中文。

2. urllib2的测试

>>> import urllib2
>>> h1 = 'http://baidu.com'
>>> urllib2.urlopen(h1)
<addinfourl at 153439532 whose fp = <socket._fileobject object at 0xb74e51ac>>
>>> h2 = u'http://baidu.com'
>>> urllib2.urlopen(h2)
<addinfourl at 153440236 whose fp = <socket._fileobject object at 0x925912c>>
>>> h3 = 'http://baidu.com?w=测试'
>>> urllib2.urlopen(h3)
<addinfourl at 153482348 whose fp = <socket._fileobject object at 0x92593ac>>
>>> h4 = u'http://baidu.com?w=测试'
>>> urllib2.urlopen(h4)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.6/urllib2.py", line 126, in urlopen
    return _opener.open(url, data, timeout)
  File "/usr/lib/python2.6/urllib2.py", line 391, in open
    response = self._open(req, data)
  File "/usr/lib/python2.6/urllib2.py", line 409, in _open
    '_open', req)
  File "/usr/lib/python2.6/urllib2.py", line 369, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.6/urllib2.py", line 1170, in http_open
    return self.do_open(httplib.HTTPConnection, req)
  File "/usr/lib/python2.6/urllib2.py", line 1142, in do_open
    h.request(req.get_method(), req.get_selector(), req.data, headers)
  File "/usr/lib/python2.6/httplib.py", line 914, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python2.6/httplib.py", line 951, in _send_request
    self.endheaders()
  File "/usr/lib/python2.6/httplib.py", line 908, in endheaders
    self._send_output()
  File "/usr/lib/python2.6/httplib.py", line 780, in _send_output
    self.send(msg)
  File "/usr/lib/python2.6/httplib.py", line 759, in send
    self.sock.sendall(str)
  File "<string>", line 1, in sendall
UnicodeEncodeError: 'ascii' codec can't encode characters in position 7-8: ordinal not in range(128)

这个测试说明， urllib2.urlopen() 可以接受ascii/unicode的英文，也可以接受ascii的中文， 但是一旦是unicode的中文url，就会报转码错误。

so，请尽量英文url，非要用中文，请记得转码。

原文链接: urllib2.urlopen的中文URL问题 | Log4D

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