问题描述
我只是在学习 Scrapy 和网站爬虫的基础知识，所以非常感谢您的意见.在教程的指导下，我从 Scrapy 构建了一个简单明了的爬虫.
I'm just picking up the basics of Scrapy and website crawlers so I would really appreciate your input. I've built a plain and simple crawler from Scrapy, guided by a tutorial.
它工作正常，但它不会像它应该的那样抓取所有页面.
It works fine but it won't crawl all the pages as it should.
我的蜘蛛代码是:
from scrapy.spider import BaseSpider
from scrapy.selector import HtmlXPathSelector
from scrapy.http.request import Request
from fraist.items import FraistItem
import re
class fraistspider(BaseSpider):
name = "fraistspider"
allowed_domain = ["99designs.com"]
start_urls = ["http://99designs.com/designer-blog/"]
def parse(self, response):
hxs = HtmlXPathSelector(response)
links = hxs.select("//div[@class='pagination']/a/@href").extract()
#We stored already crawled links in this list
crawledLinks = []
#Pattern to check proper link
linkPattern = re.compile("^(?:ftp|http|https):\/\/(?:[\w\.\-\+]+:{0,1}[\w\.\-\+]*@)?(?:[a-z0-9\-\.]+)(?::[0-9]+)?(?:\/|\/(?:[\w#!:\.\?\+=&%@!\-\/\(\)]+)|\?(?:[\w#!:\.\?\+=&%@!\-\/\(\)]+))?$")
for link in links:
# If it is a proper link and is not checked yet, yield it to the Spider
if linkPattern.match(link) and not link in crawledLinks:
crawledLinks.append(link)
yield Request(link, self.parse)
posts = hxs.select("//article[@class='content-summary']")
items = []
for post in posts:
item = FraistItem()
item["title"] = post.select("div[@class='summary']/h3[@class='entry-title']/a/text()").extract()
item["link"] = post.select("div[@class='summary']/h3[@class='entry-title']/a/@href").extract()
item["content"] = post.select("div[@class='summary']/p/text()").extract()
items.append(item)
for item in items:
yield item
输出为:
'title': [u'Design a poster in the style of Saul Bass']}
2015-05-20 16:22:41+0100 [fraistspider] DEBUG: Scraped from <200 http://nnbdesig
ner.wpengine.com/designer-blog/>
{'content': [u'Helping a company come up with a branding strategy can be
exciting\xa0and intimidating, all at once. It gives a designer the opportunity
to make a great visual impact with a brand, but requires skills in logo, print a
nd digital design. If you\u2019ve been hesitating to join a 99designs Brand Iden
tity Pack contest, here are a... '],
'link': [u'http://99designs.com/designer-blog/2015/05/07/tips-brand-ide
ntity-pack-design-success/'],
'title': [u'99designs\u2019 tips for a successful Brand Identity Pack d
esign']}
2015-05-20 16:22:41+0100 [fraistspider] DEBUG: Redirecting (301) to <GET http://
nnbdesigner.wpengine.com/> from <GET http://99designs.com/designer-blog/page/10/
>
2015-05-20 16:22:41+0100 [fraistspider] DEBUG: Redirecting (301) to <GET http://
nnbdesigner.wpengine.com/> from <GET http://99designs.com/designer-blog/page/11/
>
2015-05-20 16:22:41+0100 [fraistspider] INFO: Closing spider (finished)
2015-05-20 16:22:41+0100 [fraistspider] INFO: Stored csv feed (100 items) in: da
ta.csv
2015-05-20 16:22:41+0100 [fraistspider] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 4425,
'downloader/request_count': 16,
'downloader/request_method_count/GET': 16,
'downloader/response_bytes': 126915,
'downloader/response_count': 16,
'downloader/response_status_count/200': 11,
'downloader/response_status_count/301': 5,
'dupefilter/filtered': 41,
'finish_reason': 'finished',
'finish_time': datetime.datetime(2015, 5, 20, 15, 22, 41, 738000),
'item_scraped_count': 100,
'log_count/DEBUG': 119,
'log_count/INFO': 8,
'request_depth_max': 5,
'response_received_count': 11,
'scheduler/dequeued': 16,
'scheduler/dequeued/memory': 16,
'scheduler/enqueued': 16,
'scheduler/enqueued/memory': 16,
'start_time': datetime.datetime(2015, 5, 20, 15, 22, 40, 718000)}
2015-05-20 16:22:41+0100 [fraistspider] INFO: Spider closed (finished)
如您所见，'item_scraped_count' 是 100，但应该更多，因为总共有 122 页，每页 10 篇文章.
As you can see the 'item_scraped_count' is 100 although it should be much more since there are 122 pages in total, 10 articles per page.
从输出中我可以看到存在 301 重定向问题，但我不明白为什么这会导致问题.我尝试了另一种方法来重写我的蜘蛛代码，但在相同部分的几个条目之后它再次中断.
From the output I can see that there is a 301 redirect issue but I don't understand why is this causing problems. I've tried another approach rewriting my spider's code, but again it breaks after a few entries, around the same part.
任何帮助将不胜感激.谢谢！
Any help would be much appreciated. Thank you!
推荐答案
似乎您达到了 http://doc.scrapy.org/en/latest/topics/settings.html#concurrent-items.
对于这种情况，我将使用 CrawlSpider抓取多个页面，所以你必须定义一个 规则与 99designs.com 中的页面匹配，并修改您的解析函数以处理该项目.
For this case I'll go with an CrawlSpider to crawl multiple pages, so you have to define a rule that match the pages in 99designs.com and sightly modify your parse function to process the item.
import scrapy
from scrapy.contrib.spiders import CrawlSpider, Rule
from scrapy.contrib.linkextractors import LinkExtractor
class MySpider(CrawlSpider):
name = 'example.com'
allowed_domains = ['example.com']
start_urls = ['http://www.example.com']
rules = (
# Extract links matching 'category.php' (but not matching 'subsection.php')
# and follow links from them (since no callback means follow=True by default).
Rule(LinkExtractor(allow=('category\.php', ), deny=('subsection\.php', ))),
# Extract links matching 'item.php' and parse them with the spider's method parse_item
Rule(LinkExtractor(allow=('item\.php', )), callback='parse_item'),
)
def parse_item(self, response):
self.log('Hi, this is an item page! %s' % response.url)
item = scrapy.Item()
item['id'] = response.xpath('//td[@id="item_id"]/text()').re(r'ID: (\d+)')
item['name'] = response.xpath('//td[@id="item_name"]/text()').extract()
item['description'] = response.xpath('//td[@id="item_description"]/text()').extract()
return item
I just found this blog post that contain an useful example.
这篇关于Scrapy 在几页后停止爬行的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！