用scrapy进行网页抓取
最近用scrapy来进行网页抓取,对于pythoner来说它用起来非常方便,详细文档在这里:http://doc.scrapy.org/en/0.14/index.html
要想利用scrapy来抓取网页信息,需要先新建一个工程,scrapy startproject myproject
工程建立好后,会有一个myproject/myproject的子目录,里面有item.py(由于你要抓取的东西的定义),pipeline.py(用于处理抓取后的数据,可以保存数据库,或是其他),然后是spiders文件夹,可以在里面编写爬虫的脚本.
这里以爬取某网站的书籍信息为例:
item.py如下:
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from scrapy.item import Item, Fieldclass BookItem(Item): # define the fields for your item here like: name = Field() publisher = Field() publish_date = Field() price = Field()
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我们要抓取的东西都在上面定义好了,分别是名字,出版商,出版日期,价格,
下面就要写爬虫去网战抓取信息了,
spiders/book.py如下:
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from urlparse import urljoinimport simplejsonfrom scrapy.http import Requestfrom scrapy.contrib.spiders import CrawlSpider, Rulefrom scrapy.contrib.linkextractors.sgml import SgmlLinkExtractorfrom scrapy.selector import HtmlXPathSelectorfrom myproject.items import BookItemclass BookSpider(CrawlSpider): name = 'bookspider' allowed_domains = ['test.com'] start_urls = [ "http://test_url.com", #这里写开始抓取的页面地址(这里网址是虚构的,实际使用时请替换) ] rules = ( #下面是符合规则的网址,但是不抓取内容,只是提取该页的链接(这里网址是虚构的,实际使用时请替换) Rule(SgmlLinkExtractor(allow=(r'http://test_url/test?page_index=\d+'))), #下面是符合规则的网址,提取内容,(这里网址是虚构的,实际使用时请替换) Rule(SgmlLinkExtractor(allow=(r'http://test_rul/test?product_id=\d+')), callback="parse_item"), ) def parse_item(self, response): hxs = HtmlXPathSelector(response) item = BookItem() item['name'] = hxs.select('//div[@name="code">from scrapy import log#from scrapy.core.exceptions import DropItemfrom twisted.enterprise import adbapifrom scrapy.http import Requestfrom scrapy.exceptions import DropItemfrom scrapy.contrib.pipeline.images import ImagesPipelineimport timeimport MySQLdbimport MySQLdb.cursorsclass MySQLStorePipeline(object): def __init__(self): self.dbpool = adbapi.ConnectionPool('MySQLdb', db = 'test', user = 'user', passwd = '******', cursorclass = MySQLdb.cursors.DictCursor, charset = 'utf8', use_unicode = False ) def process_item(self, item, spider): query = self.dbpool.runInteraction(self._conditional_insert, item) query.addErrback(self.handle_error) return item def _conditional_insert(self, tx, item): if item.get('name'): tx.execute(\ "insert into book (name, publisher, publish_date, price ) \ values (%s, %s, %s, %s)", (item['name'], item['publisher'], item['publish_date'], item['price']) )?完成之后在setting.py中添加该pipeline:
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ITEM_PIPELINES = ['myproject.pipelines.MySQLStorePipeline']
?最后运行scrapy crawl bookspider就开始抓取了
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