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