python request上传文件

# -*- coding:utf-8 -*-
import requests
import json
import sys

url='xxxxg';
with open('./a.txt', 'rb') as fp:
    data=fp.read()
post = {
    'file':data,
    };

resp=requests.post(url, data=post) #post提交数据

files = {
    'file' : open('./a.txt', 'rb'),
    }
#resp=requests.post(url, files=files)  #上传文件
print resp.text