Scrapy start_urls

  • Z时代
  • 2024-01-10
  • 分类：问答

from scrapy.spider import Spider
from scrapy.selector import Selector
from dirbot.items import Website
class DmozSpider(Spider):
    name = "dmoz"
    allowed_domains = ["dmoz.org"]
    start_urls = [
        "http://www.dmoz.org/Computers/Programming/Languages/Python/Books/",
        "http://www.dmoz.org/Computers/Programming/Languages/Python/Resources/",
    ]
    def parse(self, response):
        """
        The lines below is a spider contract. For more info see:
        http://doc.scrapy.org/en/latest/topics/contracts.html
        @url http://www.dmoz.org/Computers/Programming/Languages/Python/Resources/
        @scrapes name
        """
        sel = Selector(response)
        sites = sel.xpath('//ul[@class="directory-url"]/li')
        items = []
        for site in sites:
            item = Website()
            item['name'] = site.xpath('a/text()').extract()
            item['url'] = site.xpath('a/@href').extract()
            item['description'] = site.xpath('text()').re('-\s[^\n]*\\r')
            items.append(item)
        return items

但是为什么只抓取这两个网页呢？我看到了， allowed_domains = ["dmoz.org"]但是这两页还包含指向dmoz.org域内其他页面的链接！为什么它也不会抓取它们？

回答：

start_urlsclass属性包含起始网址-仅此而已。如果你要提取其他网页的网址，parse请使用[another]回调从相应的回调请求中获取收益：

class Spider(BaseSpider):
    name = 'my_spider'
    start_urls = [
                'http://www.domain.com/'
    ]
    allowed_domains = ['domain.com']
    def parse(self, response):
        '''Parse main page and extract categories links.'''
        hxs = HtmlXPathSelector(response)
        urls = hxs.select("//*[@id='tSubmenuContent']/a[position()>1]/@href").extract()
        for url in urls:
            url = urlparse.urljoin(response.url, url)
            self.log('Found category url: %s' % url)
            yield Request(url, callback = self.parseCategory)
    def parseCategory(self, response):
        '''Parse category page and extract links of the items.'''
        hxs = HtmlXPathSelector(response)
        links = hxs.select("//*[@id='_list']//td[@class='tListDesc']/a/@href").extract()
        for link in links:
            itemLink = urlparse.urljoin(response.url, link)
            self.log('Found item link: %s' % itemLink, log.DEBUG)
            yield Request(itemLink, callback = self.parseItem)
    def parseItem(self, response):
        ...

以上是 Scrapy start_urls 的全部内容， 来源链接： utcz.com/qa/411856.html

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