python urllib2 解决重定向问题

原文地址：https://*.com/questions/554446/how-do-i-prevent-pythons-urllib2-from-following-a-redirect

由于urllib2处理重定向不会自动带上cookie，这个是比较麻烦的，找了几篇文章，还是这个靠谱，加上去以备万一。

1 以下代码是使得urllib2拥有重定向带上cookie

import urllib2

#redirect_handler = urllib2.HTTPRedirectHandler()

class MyHTTPRedirectHandler(urllib2.HTTPRedirectHandler):
    def http_error_302(self, req, fp, code, msg, headers):
        print "Cookie Manip Right Here"
        return urllib2.HTTPRedirectHandler.http_error_302(self, req, fp, code, msg, headers)

    http_error_301 = http_error_303 = http_error_307 = http_error_302

cookieprocessor = urllib2.HTTPCookieProcessor()

opener = urllib2.build_opener(MyHTTPRedirectHandler, cookieprocessor)
urllib2.install_opener(opener)

response =urllib2.urlopen("WHEREEVER")
print response.read()

print cookieprocessor.cookiejar

2 以下代码是阻止重定向，并且获得响应页面（非重定向之后的页面）。

class MyHTTPErrorProcessor(urllib2.HTTPErrorProcessor):

    def http_response(self, request, response):
        code, msg, hdrs = response.code, response.msg, response.info()

        # only add this line to stop 302 redirection.
        if code == 302: return response

        if not (200 <= code < 300):
            response = self.parent.error(
                'http', request, response, code, msg, hdrs)
        return response

    https_response = http_response

cj = cookielib.CookieJar()
opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj), MyHTTPErrorProcessor)

class NoRedirection(urllib2.HTTPErrorProcessor):

    def http_response(self, request, response):
        return response

    https_response = http_response

cj = cookielib.CookieJar()
opener = urllib2.build_opener(NoRedirection, urllib2.HTTPCookieProcessor(cj))
data = {}
response = opener.open('http://www.example.com', urllib.urlencode(data))
if response.code == 302:
    redirection_target = response.headers['Location']

这里响应头部的Location字段就是重定向的url。

接下来的文章会利用这两个测试学校图书馆用户登录的问题