代码如下:

import jsonimport requestsr = requests.post(url, data = {
   "a": json.dumps({
   "b": "c"})}); #url为随意URL

使用Fiddler抓包，虽然在WebForms里面看到格式如下:

但是在Raw中看到结果如下:

即自动执行了urlencode，查看requests/models.py源码发现，如果数据可迭代，即自动加入"application/x-www-form-urlencoded"头，并且执行urlencode:

PreparedRequest类的prepare_body方法中

if data:    body = self._encode_params(data)    if isinstance(data, basestring) or hasattr(data, 'read'):        content_type = None    else:        content_type = 'application/x-www-form-urlencoded'

RequestEncodingMixin类中_encode_params(data)方法中

if isinstance(data, (str, bytes)):    return dataelif hasattr(data, 'read'):    return dataelif hasattr(data, '__iter__'):    result = []    for k, vs in to_key_val_list(data):        if isinstance(vs, basestring) or not hasattr(vs, '__iter__'):            vs = [vs]        for v in vs:            if v is not None:                result.append(                    (k.encode('utf-8') if isinstance(k, str) else k,                     v.encode('utf-8') if isinstance(v, str) else v))    return urlencode(result, doseq=True)else:    return data

解决办法:

import jsonimport requestsheaders = {
   "Content-Type": "application/x-www-form-urlencoded"} data = "a=%s" %  json.dumps({
   "b": "c"})r = requests.post(url, data = data, headers = headers);