9.scrapy pycharm调试小技巧，请求一次，下次直接调试，不必每次都启动整个爬虫，重新请求一整遍

pycharm调试技巧：调试时，请求一次，下次直接调试，不必每次都启动整个爬虫，重新请求一整遍

【用法】cmd命令运行：scrapy shell 网址

第一步，cmd进行一次请求：

scrapy shell http://blog.jobbole.com/114633/

返回详情：

C:\Users\Administrator>scrapy shell http://blog.jobbole.com/114633/
2019-05-06 14:47:09 [scrapy.utils.log] INFO: Scrapy 1.6.0 started (bot: scrapybo
t)
2019-05-06 14:47:09 [scrapy.utils.log] INFO: Versions: lxml 4.3.3.0, libxml2 2.9
.5, cssselect 1.0.3, parsel 1.5.1, w3lib 1.20.0, Twisted 19.2.0, Python 3.7.3 (v
3.7.3:ef4ec6ed12, Mar 25 2019, 22:22:05) [MSC v.1916 64 bit (AMD64)], pyOpenSSL
19.0.0 (OpenSSL 1.1.1b  26 Feb 2019), cryptography 2.6.1, Platform Windows-7-6.1
.7601-SP1
2019-05-06 14:47:09 [scrapy.crawler] INFO: Overridden settings: {'DUPEFILTER_CLA
SS': 'scrapy.dupefilters.BaseDupeFilter', 'LOGSTATS_INTERVAL': 0}
2019-05-06 14:47:09 [scrapy.extensions.telnet] INFO: Telnet Password: ad4920d938
db236a
2019-05-06 14:47:09 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.corestats.CoreStats',
 'scrapy.extensions.telnet.TelnetConsole']
2019-05-06 14:47:10 [scrapy.middleware] INFO: Enabled downloader middlewares:
['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.httpproxy.HttpProxyMiddleware',
 'scrapy.downloadermiddlewares.stats.DownloaderStats']
2019-05-06 14:47:10 [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']
2019-05-06 14:47:10 [scrapy.middleware] INFO: Enabled item pipelines:
[]
2019-05-06 14:47:10 [scrapy.extensions.telnet] INFO: Telnet console listening on
 127.0.0.1:6023
2019-05-06 14:47:10 [scrapy.core.engine] INFO: Spider opened
2019-05-06 14:47:11 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://blog.j
obbole.com/114633/> (referer: None)
[s] Available Scrapy objects:
[s]   scrapy     scrapy module (contains scrapy.Request, scrapy.Selector, etc)
[s]   crawler    <scrapy.crawler.Crawler object at 0x0000000004A07C50>
[s]   item       {}
[s]   request    <GET http://blog.jobbole.com/114633/>
[s]   response   <200 http://blog.jobbole.com/114633/>
[s]   settings   <scrapy.settings.Settings object at 0x0000000004A07A90>
[s]   spider     <DefaultSpider 'default' at 0x4db6e48>
[s] Useful shortcuts:
[s]   fetch(url[, redirect=True]) Fetch URL and update local objects (by default
, redirects are followed)
[s]   fetch(req)                  Fetch a scrapy.Request and update local object
s
[s]   shelp()           Shell help (print this help)
[s]   view(response)    View response in a browser

第二步，进行调试（好处，只要请求次，其它调试都不用再次请求）：

#用xpath
>>> title=response.xpath("//div[@class='entry-header']/h1/text()")

#title是一个对象
>>> print(title)
[<Selector xpath="//div[@class='entry-header']/h1/text()" data='“三次握手，四次挥手”你真的懂吗？'>]

#返回列表extract()方法
>>> title.extract()
['“三次握手，四次挥手”你真的懂吗？']

#返回列表值
>>> title.extract()[0]
'“三次握手，四次挥手”你真的懂吗？'