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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):
...
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?
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