python：带有二进制数据的 HTTP PUT

Question

所以我按照answers to another question 的建议调整了 urllib2：

class HttpRequest(urllib2.Request):
  def __init__(self, *args, **kwargs):
    self._method = kwargs.pop('method', 'GET')
    urllib2.Request.__init__(self, *args, **kwargs)
  def get_method(self):
    return self._method

它适用于带有 JSON 的 PUT：

req = HttpRequest(url=url, method='PUT', 
    data=json.dumps(metadata))
response = urllib2.urlopen(req)

但它失败了data=二进制数据（下面的部分堆栈跟踪）：

  File "c:\appl\python\2.7.2\lib\urllib2.py", line 126, in urlopen
    return _opener.open(url, data, timeout)
  File "c:\appl\python\2.7.2\lib\urllib2.py", line 394, in open
    response = self._open(req, data)
  File "c:\appl\python\2.7.2\lib\urllib2.py", line 412, in _open
    '_open', req)
  File "c:\appl\python\2.7.2\lib\urllib2.py", line 372, in _call_chain
    result = func(*args)
  File "c:\appl\python\2.7.2\lib\urllib2.py", line 1199, in http_open
    return self.do_open(httplib.HTTPConnection, req)
  File "c:\appl\python\2.7.2\lib\urllib2.py", line 1168, in do_open
    h.request(req.get_method(), req.get_selector(), req.data, headers)
  File "c:\appl\python\2.7.2\lib\httplib.py", line 955, in request
    self._send_request(method, url, body, headers)
  File "c:\appl\python\2.7.2\lib\httplib.py", line 989, in _send_request
    self.endheaders(body)
  File "c:\appl\python\2.7.2\lib\httplib.py", line 951, in endheaders
    self._send_output(message_body)
  File "c:\appl\python\2.7.2\lib\httplib.py", line 809, in _send_output
    msg += message_body
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 10: ordinal
 not in range(128)

有什么办法可以解决这个问题吗？

Answer 1

因为

data 应该是标准 application/x-www-form-urlencoded 格式的缓冲区。 urllib.urlencode() 函数采用 2 元组的映射或序列，并以这种格式返回一个字符串。

来自 urllib2 文档

Answer 2

您正在尝试将 python unicode 字符串自动转换为常规字节字符串。 JSON 始终是 unicode，但 HTTP 必须发送字节。如果您确信接收方会理解特定编码中的 json 编码数据，则可以这样编码：

>>> urllib2.urlopen(urllib2.Request("http://example.com", data=u'\u0ca0'))
Traceback (most recent call last):
  ...
UnicodeEncodeError: 'ascii' codec cannot encode character u'\u0ca0' in position 0: ordinal not in range(128)
>>> urllib2.urlopen(urllib2.Request("http://example.com", 
...                                 data=u'\u0ca0'.encode('utf-8')))
<addinfourl at 15700984 whose fp = <socket._fileobject object at 0xdfbe50>>
>>> 

注意.encode('utf-8')，它将unicode 转换为utf-8 中的str。隐式转换将使用 ascii，它不能编码非 ascii 字符。

tl;博士... data=json.dumps(blabla).encode('utf-8') ...

Answer 3

根据urllib2 documentation，您需要对字节字符串进行百分比编码。