http.py 文件源码

def read(self, buf_len):
        """
        Implementation note: due to a constraint of the requests library, the
        buf_len that is used the first time this method is called will cause
        all future requests to ``read`` to have the same ``buf_len`` even if
        a different ``buf_len`` is passed in on subsequent requests.
        """
        if self._iter is None:  # lazy load response body iterator
            method = self.input_spec.get('method', 'GET').upper()
            headers = self.input_spec.get('headers', {})
            params = self.input_spec.get('params', {})
            req = requests.request(
                method, self.input_spec['url'], headers=headers, params=params,
                stream=True, allow_redirects=True)
            req.raise_for_status()  # we have the response headers already
            self._iter = req.iter_content(buf_len, decode_unicode=False)

        try:
            return six.next(self._iter)
        except StopIteration:
            return b''