【scrapy】使用方法概要（四）(转)

【请初学者作为参考，不建议高手看这个浪费时间】

上一篇文章，我们抓取到了一大批代理ip，本篇文章介绍如何实现downloaderMiddleware，达到随即使用代理ip对目标网站进行抓取的。

抓取的目标网站是现在炙手可热的旅游网站 www.qunar.com, 目标信息是qunar的所有seo页面，及页面的seo相关信息。

qunar并没有一般网站具有的 robots.txt文件，所以无法利用列表进行抓取，但是，可以发现，qunar的seo页面主要部署在

http://www.qunar.com/routes/ 下，这个页面为入口文件，由此页面及此页面上所有带有routes的链接开始递归的抓取所有带有routes/字段的链接即可。

开始吧

目标信息为目标站点的seo信息，所以为head中的meta和description字段。

 1 # Define here the models for your scraped items
 2 #
 3 # See documentation in:
 4 # http://doc.scrapy.org/topics/items.html
 5 
 6 from scrapy.item import Item, Field
 7 
 8 class SitemapItem(Item):
 9     # define the fields for your item here like:
10     # name = Field()
11     url = Field()
12     keywords = Field()
13     description = Field()

因为要使用代理ip，所以需要实现自己的downloadermiddlerware，主要功能是从代理ip文件中随即选取一个ip端口作为代理服务，代码如下

 1 import random
 2 
 3 class ProxyMiddleware(object):
 4     def process_request(self, request, spider):
 5         fd = open('/home/xxx/services_runenv/crawlers/sitemap/sitemap/data/proxy_list.txt','r')
 6         data = fd.readlines()
 7         fd.close()
 8         length = len(data)
 9         index  = random.randint(0, length -1)
10         item   = data[index]
11         arr    = item.split(',')
12         request.meta['proxy'] = 'http://%s:%s' % (arr[0],arr[1])

最重要的还是爬虫，主要功能是提取页面所有的链接，把满足条件的url实例成Request对象并yield，同时提取页面的keywords，description信息，以item的形式yield，代码如下:

 1 from scrapy.selector import HtmlXPathSelector
 2 from sitemap.items import SitemapItem
 3 
 4 import urllib
 5 import simplejson
 6 import exceptions
 7 import pickle
 8 
 9 class SitemapSpider(CrawlSpider):
10     name = 'sitemap_spider'
11     allowed_domains = ['qunar.com']
12     start_urls = ['http://www.qunar.com/routes/']
13 
14     rules = (
15         #Rule(SgmlLinkExtractor(allow=(r'http://www.qunar.com/routes/.*')), callback='parse'),
16         #Rule(SgmlLinkExtractor(allow=('http:.*/routes/.*')), callback='parse'),
17     )
18 
19     def parse(self, response):
20         item = SitemapItem()
21         x         = HtmlXPathSelector(response)
22         raw_urls  = x.select("//a/@href").extract()
23         urls      = []
24         for url in raw_urls:
25             if 'routes' in url:
26                 if 'http' not in url:
27                     url = 'http://www.qunar.com' + url
28                 urls.append(url)
29 
30         for url in urls:
31             yield Request(url)
32 
33         item['url']         = response.url.encode('UTF-8')
34         arr_keywords        = x.select("//meta[@name='keywords']/@content").extract()
35         item['keywords']    = arr_keywords[0].encode('UTF-8')
36         arr_description     = x.select("//meta[@name='description']/@content").extract()
37         item['description'] = arr_description[0].encode('UTF-8')
38 
39         yield item

pipe文件比较简单，只是把抓取到的数据存储起来，代码如下

 1 # Define your item pipelines here
 2 #
 3 # Don't forget to add your pipeline to the ITEM_PIPELINES setting
 4 # See: http://doc.scrapy.org/topics/item-pipeline.html
 5 
 6 class SitemapPipeline(object):
 7     def process_item(self, item, spider):
 8         data_path = '/home/xxx/services_runenv/crawlers/sitemap/sitemap/data/output/sitemap_data.txt'
 9         fd = open(data_path, 'a')
10         line = str(item['url']) + '#$#' + str(item['keywords']) + '#$#' + str(item['description']) + '
'
11         fd.write(line)
12         fd.close
13         return item

最后附上的是setting.py文件

# Scrapy settings for sitemap project
#
# For simplicity, this file contains only the most important settings by
# default. All the other settings are documented here:
#
#     http://doc.scrapy.org/topics/settings.html
#

BOT_NAME = 'sitemap hello,world~!'
BOT_VERSION = '1.0'

SPIDER_MODULES = ['sitemap.spiders']
NEWSPIDER_MODULE = 'sitemap.spiders'
USER_AGENT = '%s/%s' % (BOT_NAME, BOT_VERSION)

DOWNLOAD_DELAY = 0

ITEM_PIPELINES = [
    'sitemap.pipelines.SitemapPipeline'
]

DOWNLOADER_MIDDLEWARES = {
    'scrapy.contrib.downloadermiddleware.httpproxy.HttpProxyMiddleware': 110,
    'sitemap.middlewares.ProxyMiddleware': 100,
    }

CONCURRENT_ITEMS = 128
CONCURRENT_REQUEST = 64
CONCURRENT_REQUEST_PER_DOMAIN = 64


LOG_ENABLED = True
LOG_ENCODING = 'utf-8'
LOG_FILE = '/home/xxx/services_runenv/crawlers/sitemap/sitemap/log/sitemap.log'
LOG_LEVEL = 'DEBUG'
LOG_STDOUT = False

对scrapy的介绍将告一段落，更复杂的应用还没有接触过，想等看完redis的源码，再来研究下scrapy的源码~~ 希望通过分享能给正在入门scrapy的童鞋带来帮助~

喜欢一起简单，实用的东西，拒绝复杂花哨，我不是GEEK.