四.scrapy XMLFeedSpider用法

一：在何时才会使用到XMLFeedSpider

 处理RSS订阅信息，RSS是一种信息聚合技术，是基于XML

二：举例

新浪微博 http://blog.sina.com.cn/u/1649020634

点击订阅后 

复制链接http://blog.sina.com.cn/rss/1649020634.xml

看到是xml文件

三：如何抓取

scrapy startproject xmlspider

cd xmlspider

scrapy genspider -t xmlfeed myxmlspider sina.com.cn

# -*- coding: utf-8 -*-from scrapy.spiders import XMLFeedSpiderclass MyxmlspiderSpider(XMLFeedSpider):    name = 'myxmlspider'    allowed_domains = ['sina.com.cn']    start_urls = ['http://blog.sina.com.cn/rss/1615888477.xml']    iterator = 'iternodes' # you can change this; see the docs    itertag = 'rss' # change it accordingly    def parse_node(self, response, selector):        i = {}        i['title'] = selector.xpath("/rss/channel/item/title/text()").extract()        i['link'] = selector.xpath("/rss/channel/item/link/text()").extract()        i['author'] = selector.xpath("/rss/channel/item/author/text()").extract()        for j in range(len(i['title'])):            print u'第%d篇文章：'%(j+1)            print u'标题是：'            print i['title'][j]            print u'链接是：'            print i['link'][j]            print u'作者是：'            print i['author'][j]            print '--'*10        return i

注意 iterator:默认秩代器为‘’，itertag默认从rss开始抓取