python - 为什么我直接用requests爬网页可以，但用scrapy不行？

Question

class job51():
    def __init__(self):
        self.headers={
   'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
    'Accept-Encoding':'gzip, deflate, sdch',
   'Accept-Language': 'zh-CN,zh;q=0.8',
    'Cache-Control': 'max-age=0',
   'User-Agent':'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.71 Safari/537.36',
    'Cookie':''
}

    def start(self):
        html=session.get("http://my.51job.com/cv/CResume/CV_CResumeManage.php",headers=self.headers)
        self.parse(html)

    def parse(self,response):
        tree=lxml.etree.HTML(response.text)
        resume_url=tree.xpath('//tbody/tr[@class="resumeName"]/td[1]/a/@href')
        print (resume_url[0]

能爬到我想要的结果，就是简历的url,但是用scrapy,同样的headers,页面好像停留在登录页面？

class job51(Spider):
    name = "job51"
    #allowed_domains = ["my.51job.com"]
    start_urls = ["http://my.51job.com/cv/CResume/CV_CResumeManage.php"]
    headers={
   'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
    'Accept-Encoding':'gzip, deflate, sdch',
   'Accept-Language': 'zh-CN,zh;q=0.8',
    'Cache-Control': 'max-age=0',
   'User-Agent':'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.71 Safari/537.36',
    'Cookie':''
}

    def start_requests(self):
        yield  Request(url=self.start_urls[0],headers=self.headers,callback=self.parse)

    def parse(self,response):
        #tree=lxml.etree.HTML(text)
        selector=Selector(response)
        print ("<<<<<<<<<<<<<<<<<<<<<",response.text)
        resume_url=selector.xpath('//tr[@class="resumeName"]/td[1]/a/@href')
        print (">>>>>>>>>>>>",resume_url)

输出的结果：

scrapy.utils.log] INFO: Overridden settings: {'BOT_NAME': 'job51', 'SPIDER_MODULES': ['job51.spiders'], 'ROBOTSTXT_OBEY': True, 'NEWSPIDER_MODULE': 'job51.spiders'}
2017-04-11 10:58:31 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.logstats.LogStats',
 'scrapy.extensions.corestats.CoreStats',
 'scrapy.extensions.telnet.TelnetConsole']
2017-04-11 10:58:32 [scrapy.middleware] INFO: Enabled downloader middlewares:
['scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware',
 'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
 'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
 'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
 'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
 'scrapy.downloadermiddlewares.retry.RetryMiddleware',
 'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
 'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
 'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
 'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
 'scrapy.downloadermiddlewares.stats.DownloaderStats']
2017-04-11 10:58:32 [scrapy.middleware] INFO: Enabled spider middlewares:
['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
 'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
 'scrapy.spidermiddlewares.referer.RefererMiddleware',
 'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
 'scrapy.spidermiddlewares.depth.DepthMiddleware']
2017-04-11 10:58:32 [scrapy.middleware] INFO: Enabled item pipelines:
[]
2017-04-11 10:58:32 [scrapy.core.engine] INFO: Spider opened
2017-04-11 10:58:32 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2017-04-11 10:58:32 [scrapy.extensions.telnet] DEBUG: Telnet console listening on 127.0.0.1:6023
2017-04-11 10:58:33 [scrapy.core.engine] DEBUG: Crawled (404) <GET http://my.51job.com/robots.txt> (referer: None)
2017-04-11 10:58:33 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://my.51job.com/cv/CResume/CV_CResumeManage.php> (referer: None)
<<<<<<<<<<<<<<<<<<<<< <script>window.location='https://login.51job.com/login.php?url=http://my.51job.com%2Fcv%2FCResume%2FCV_CResumeManage.php%3F7087';</script>
>>>>>>>>>>>> []
2017-04-11 10:58:33 [scrapy.core.scraper] ERROR: Spider error processing <GET http://my.51job.com/cv/CResume/CV_CResumeManage.php> (referer: None)
Traceback (most recent call last):
  File "d:\python35\lib\site-packages\scrapy\utils\defer.py", line 102, in iter_errback
    yield next(it)
  File "d:\python35\lib\site-packages\scrapy\spidermiddlewares\offsite.py", line 29, in process_spider_output
    for x in result:
  File "d:\python35\lib\site-packages\scrapy\spidermiddlewares\referer.py", line 22, in <genexpr>
    return (_set_referer(r) for r in result or ())
  File "d:\python35\lib\site-packages\scrapy\spidermiddlewares\urllength.py", line 37, in <genexpr>
    return (r for r in result or () if _filter(r))
  File "d:\python35\lib\site-packages\scrapy\spidermiddlewares\depth.py", line 58, in <genexpr>
    return (r for r in result or () if _filter(r))
  File "E:\WorkGitResp\spider\job51\job51\spiders\51job_resume.py", line 43, in parse
    yield Request(resume_url[0],headers=self.headers,callback=self.getResume)
  File "d:\python35\lib\site-packages\parsel\selector.py", line 58, in __getitem__
    o = super(SelectorList, self).__getitem__(pos)
IndexError: list index out of range
2017-04-11 10:58:33 [scrapy.core.engine] INFO: Closing spider (finished)
2017-04-11 10:58:33 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 628,
 'downloader/request_count': 2,
 'downloader/request_method_count/GET': 2,
 'downloader/response_bytes': 5743,
 'downloader/response_count': 2,
 'downloader/response_status_count/200': 1,
 'downloader/response_status_count/404': 1,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2017, 4, 11, 2, 58, 33, 275634),
 'log_count/DEBUG': 3,
 'log_count/ERROR': 1,
 'log_count/INFO': 7,
 'response_received_count': 2,
 'scheduler/dequeued': 1,
 'scheduler/dequeued/memory': 1,
 'scheduler/enqueued': 1,
 'scheduler/enqueued/memory': 1,
 'spider_exceptions/IndexError': 1,
 'start_time': datetime.datetime(2017, 4, 11, 2, 58, 32, 731603)}
2017-04-11 10:58:33 [scrapy.core.engine] INFO: Spider closed (finished)

Answer 1

ログには 404 が表示されます。scrapy 設定でリダイレクトが無効になっているかどうかを確認してください。

Answer 2

リーリー

ここから、scrapy を使用して作成したクローラーがログインページにリダイレクトされていることがわかります。したがって、エラーが報告されます。リクエストとscrapyを使用するときにパッケージをキャプチャして、その応答コンテンツを確認し、リクエストヘッダーがまったく同じであるかどうかを確認することをお勧めします。 Cookie の有効期限が切れているか、Scrapy がこの方法で Cookie を転送できないのではないかと思います。私は Scrapy にあまり詳しくありませんが、問題は Cookie にあるはずです。

Answer 3

セッションリクエストに使用した実際のリクエストヘッダーにはおそらくすでにCookieが読み込まれているため、上記のようにリクエストヘッダーを比較することをお勧めします