Python请求:requests.exceptions.TooManyRedirects:超过30个重定向

Question

我试图使用python-requests库抓取此页面

import requests
from lxml import etree,html

url = 'http://www.amazon.in/b/ref=sa_menu_mobile_elec_all?ie=UTF8&node=976419031'
r = requests.get(url)
tree = etree.HTML(r.text)
print tree

但我得到了上述错误.(TooManyRedirects)我试图使用allow_redirects参数但同样的错误

r = requests.get(url, allow_redirects=True)

我甚至试图发送标题和数据以及网址,但我不确定这是否是正确的方法.

headers = {'content-type': 'text/html'}
payload = {'ie':'UTF8','node':'976419031'}
r = requests.post(url,data=payload,headers=headers,allow_redirects=True)

如何解决此错误.出于好奇,我甚至尝试过美丽的汤,但我得到了不同但同样的错误

page = BeautifulSoup(urllib2.urlopen(url))

urllib2.HTTPError: HTTP Error 301: The HTTP server returned a redirect error that would lead to an infinite loop.
The last 30x error message was:
Moved Permanently

Answer 1

亚马逊正在将您的请求http://www.amazon.in/b?ie=UTF8&node=976419031重定向到http://www.amazon.in/electronics/b?ie=UTF8&node=976419031,然后重定向到,之后您已进入循环:

>>> loc = url
>>> seen = set()
>>> while True:
...     r = requests.get(loc, allow_redirects=False)
...     loc = r.headers['location']
...     if loc in seen: break
...     seen.add(loc)
...     print loc
... 
http://www.amazon.in/b?ie=UTF8&node=976419031
http://www.amazon.in/electronics/b?ie=UTF8&node=976419031
>>> loc
http://www.amazon.in/b?ie=UTF8&node=976419031

因此,您的原始网址A不会重定向新的网址B,重定向到C,重定向到B等.

显然,亚马逊基于User-Agent标头执行此操作,此时它会设置一个cookie,以便发送回请求.以下作品:

>>> s = requests.Session()
>>> s.headers['User-Agent'] = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.131 Safari/537.36'
>>> r = s.get(url)
>>> r
<Response [200]>

这创建了一个会话(为了便于重复使用和cookie持久性),以及Chrome用户代理字符串的副本.请求成功(返回200响应).

Answer 2

通过明确指定计数可以增加max_redirect，如下例所示：

session = requests.Session()
session.max_redirects = 60
session.get('http://www.amazon.com')