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scrapy

安装

sudo apt-get install gcc python-virutalenv python-dev libxml2-dev
libxslt-dev

pip install Scrapy

抓取

scrapy crawl douban_book
参数

scrapy crawl myspider -a category=electronics -a domain=system

Spiders receive arguments in their constructors:

class MySpider(BaseSpider):
    name = 'myspider'

    def __init__(self, category='', domain=None):
        self.start_urls = ['http://www.example.com/categories/%s' % category]
        self.domain = domain
    ...

selector

样例
<html>
     <head>
         <base href='http://example.com/' />
         <title>Example website</title>
     </head>
     <body>
         <div id='images'>
             <a href='image1.html'>Name: My image 1 <br />
                <img src='image1_thumb.jpg' /></a>
             <a href='image2.html'>Name: My image 2 <br />
                <img src='image2_thumb.jpg' /></a>
             <a href='image3.html'>Name: My image 3 <br />
                <img src='image3_thumb.jpg' /></a>
             <a href='image4.html'>Name: My image 4 <br />
                <img src='image4_thumb.jpg' /></a>
             <a href='image5.html'>Name: My image 5 <br />
                <img src='image5_thumb.jpg' /></a>
         </div>
     </body>
</html>

xpath
    选择属性使用@
    选择节点文字text()
    选择某节点href属性@href
css
    选择属性使用::
    选择节点文字::text
    选择某节点href属性::attr(href)

xpath

    sel.xpath('//title/text()') -- [<Selector (text) xpath=//title/text()>]
    sel.xpath('//title/text()').extract() -- [u'Example website']
    sel.xpath('//base/@href').extract() -- [u'http://example.com/']
    sel.xpath('//a[contains(@href, "image")]/@href').extract()
        [u'image1.html', u'image2.html', u'image3.html',
         u'image4.html', u'image5.html']
    sel.xpath('//a[contains(@href, "image")]/img/@src').extract()
        [u'image1_thumb.jpg', u'image2_thumb.jpg', u'image3_thumb.jpg',
         u'image4_thumb.jpg', u'image5_thumb.jpg']

css

    sel.css('title::text').extract() -- [u'Example website']
    sel.css('base::attr(href)').extract() -- [u'http://example.com/']
    sel.css('a[href*=image]::attr(href)').extract()
    [u'image1.html', u'image2.html', u'image3.html', u'image4.html', u'image5.html']
    sel.css('a[href*=image] img::attr(src)').extract()
        [u'image1_thumb.jpg', u'image2_thumb.jpg', u'image3_thumb.jpg',
         u'image4_thumb.jpg', u'image5_thumb.jpg']