python爬虫之Scrapy 使用代理配置

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,
}