scrapy模拟登陆知乎出现重定向无法登陆问题

• 当我使用scrapy想进行模拟登陆, 然后抓取首页的问题和答案时, 一直显示重定向问题

pythonfrom scrapy.contrib.spiders import CrawlSpider, Rule
from scrapy.selector import Selector
from scrapy.contrib.linkextractors.sgml import SgmlLinkExtractor
from scrapy.http import Request, FormRequest
from zhihu.items import ZhihuItem



class ZhihuSipder(CrawlSpider) :
    name = "zhihu"
    allowed_domains = ["www.zhihu.com"]
    start_urls = [
        "http://www.zhihu.com"
    ]
    rules = (
        Rule(SgmlLinkExtractor(allow = r'http://www\.zhihu\.com/question/\d+'), callback = 'parse_page'),
    )

    def start_requests(self):
        return [Request("https://www.zhihu.com/login", callback = self.post_login)]

    #FormRequeset出问题了
    def post_login(self, response):
        print 'Preparing login'
        xsrf = Selector(response).xpath('//input[@name="_xsrf"]/@value').extract()[0]
        print xsrf
        ##############
        return [FormRequest.from_response(response,  #"http://www.zhihu.com/login",
                            formdata = {
                            '_xsrf': xsrf,
                            'email': '@qq.com',
                            'password': '123456',
                            'rememberme': 'y',
                            },
                            callback = self.parse_page
                            )]

    def parse_page(self, response):
        problem = Selector(response)
        item = ZhihuItem()
        item['url'] = response.url
        item['title'] = problem.xpath('//h2[@class="zm-item-title zm-editable-content"]/text()').extract()
        item['description'] = problem.xpath('//div[@class="zm-editable-content"]/text()').extract()
        item['answer']= problem.xpath('//div[@class=" zm-editable-content clearfix"]/text()').extract()
        return item

使用命令运行爬虫, 可以正确打印xsrf, 但无法成功登陆

$ scrapy crawl zhihu

错误结果如下
2014-12-18 14:45:11+0800 [zhihu] INFO: Spider opened
2014-12-18 14:45:11+0800 [zhihu] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2014-12-18 14:45:11+0800 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6023
2014-12-18 14:45:11+0800 [scrapy] DEBUG: Web service listening on 127.0.0.1:6080
2014-12-18 14:45:11+0800 [zhihu] DEBUG: Redirecting (301) to <GET https://www.zhihu.com/> from <GET https://www.zhihu.com/login>
2014-12-18 14:45:11+0800 [zhihu] DEBUG: Redirecting (302) to <GET http://www.zhihu.com/> from <GET https://www.zhihu.com/>
2014-12-18 14:45:12+0800 [zhihu] DEBUG: Crawled (200) <GET http://www.zhihu.com/> (referer: None)
Preparing login
d117e46de0dcc5e8ee2f0c7031fcafe9
2014-12-18 14:45:12+0800 [zhihu] DEBUG: Redirecting (302) to <GET http://www.zhihu.com/> from <POST http://www.zhihu.com/login>
2014-12-18 14:45:12+0800 [zhihu] DEBUG: Filtered duplicate request: <GET http://www.zhihu.com/> - no more duplicates will be shown (see DUPEFILTER_DEBUG to show all duplicates)
2014-12-18 14:45:12+0800 [zhihu] INFO: Closing spider (finished)
2014-12-18 14:45:12+0800 [zhihu] INFO: Dumping Scrapy stats:

希望得到解答, 为什么不能成功登陆, 非常疑惑, 非常感谢

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上面其实已经成功登录, 后来自己测试过了, 只不过没有调用一个抓取页面url的函数