Python2 基于urllib2 的HTTP请求类

一个利用urllib2模块编写的下载器，虽然有了requests模块，但是毕竟标准库

 import urllib2,random

 class strong_down():
     def __init__(self):
        #ip_list和agent_list可以自己写到config文件中，然后读出来
　　　　　　self.proxy_ip_list = ['122.224.227.202:3128',
                               '182.254.220.21:3128',
                               '123.7.115.141:9797',
                               '183.61.236.54:3128',
                               '124.88.67.31:843',
                               '120.24.73.165:3128']
         self.user_agent_list = ["Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/22.0.1207.1 Safari/537.1",
                                 "Mozilla/5.0 (X11; CrOS i686 2268.111.0) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.57 Safari/536.11"
                                 ]
         self.proxy_ip_num = len(self.proxy_ip_list)
         self.user_agent_num = len(self.user_agent_list)

     def proxy_down(self,url,time_out=5,num_retries=3):
         proxy_ip = self.proxy_ip_list[random.randint(0,self.proxy_ip_num-1)]
         user_agent = self.user_agent_list[random.randint(0,self.user_agent_num-1)]
         proxy_handler = urllib2.ProxyHandler({'http':proxy_ip})
         opener = urllib2.build_opener(proxy_handler)
         request = urllib2.Request(url,headers={'User-Agent':user_agent})
         #print request.headers
         try:
             response = opener.open(request,timeout=time_out)
             html = response.read()
             if html == None:print 'none'
             return  html
         except urllib2.URLError, e:
             if hasattr(e,"code"):
                 print '',e.code,e.reason
             if hasattr(e,"reason"):
                 print '',e.reason
             if num_retries>1:
                 return self.proxy_down(url,time_out,num_retries-1)
         except Exception as e:
             print 'error:',e
             if num_retries>0:
                 print 'proxy try...'
                 return self.proxy_down(url,time_out,num_retries-1)
             else:
                 print u'代理也没diao用'
                 return  None

     def down(self,url,time_out=5,num_retries=3):
         user_agent = self.user_agent_list[random.randint(0,self.user_agent_num-1)]
         request = urllib2.Request(url,headers={'User-Agent':user_agent})
         try:
             response = urllib2.urlopen(request,timeout=time_out)
             html = response.read()
             return html
         except urllib2.URLError, e:
             if hasattr(e,"code"):
                 print '', e.code,e.reason,e.msg
             if hasattr(e,"reason"):
                 print '', e.reason
             if num_retries>0:
                 print 'try...'
                 return self.down(url,time_out,num_retries-1)
         except Exception as e:
             print 'error:',e
             if num_retries>0:
                 print 'try...'
                 return self.down(url,time_out,num_retries-1)

             #代理
             if num_retries <=0:
                 return self.proxy_down(url,time_out,num_retries=3)