利用requests发出请求时可能会发生异常，requests中有一个exception库用来区分这些异常。
http协议是基于tcp/ip协议的，tcp/ip三次握手，因此可以在请求中定义等待时间，超出等待时间仍未到达则请求失败。如requests.get(url,timeout=(3,7)),requests.get(url,timeout=10)
import json import requests from requests import exceptions URL = ‘https://api.github.com‘ #构建uri def build_uri(endpoint): return ‘/‘.join([URL,endpoint]) def timeout_request(): try: response = requests.get(build_uri(‘user/emails‘),timeout=5) response.raise_for_status() except exceptions.Timeout as e: print(e) except exceptions.HTTPError as e: print(e) if __name__==‘__main__‘: timeout_request()
原文：http://www.cnblogs.com/HJhj/p/7354324.html