useragent_middlewares.py 文件源码

def process_request(self, request, spider):
        ua = random.choice(self.user_agent_list)
        if ua:
            #???????useragent
            #print "********Current UserAgent:%s************" %ua
            #??
            log.msg('Current UserAgent: '+ua, _level=logging.INFO)
            request.headers.setdefault('User-Agent', ua)

    #the default user_agent_list composes chrome,I E,firefox,Mozilla,opera,netscape
    #for more user agent strings,you can find it in http://www.useragentstring.com/pages/useragentstring.php