python爬虫之Scrapy 使用代理配置

http://www.pythontab.com/html/2014/pythonweb_0326/724.html

在爬取网站内容的时候，最常遇到的问题是：网站对IP有限制，会有防抓取功能，最好的办法就是IP轮换抓取（加代理）

下面来说一下Scrapy如何配置代理，进行抓取

1.在Scrapy工程下新建“middlewares.py”

# Importing base64 library because we'll need it ONLY in case if the proxy we are going to use requires authentication
import  base64
# Start your middleware class
class  ProxyMiddleware( object ):
    # overwrite process request
    def  process_request( self , request, spider):
        # Set the location of the proxy
        request.meta[ 'proxy' ]  =  "http://YOUR_PROXY_IP:PORT"

        # Use the following lines if your proxy requires authentication
        proxy_user_pass  =  "USERNAME:PASSWORD"
        # setup basic authentication for the proxy
        encoded_user_pass  =  base64.encodestring(proxy_user_pass)
        request.headers[ 'Proxy-Authorization' ]  =  'Basic '  +  encoded_user_pass

2.在项目配置文件里(./pythontab/settings.py)添加

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