scrapy基础知识之随机切换fake-useragent 库的使用：

pip install fake-useragent

from fake_useragent import UserAgent
ua = UserAgent()

middlewares.py

 from fake_useragent import UserAgent

 class RandomUserAgent(object):
     # def __init__(self,crawl):
     #     super(RandomUserAgent,self).__init__()
     #     self.ua=UserAgent()
     def process_request(self, request, spider):
         #useragent = random.choice(USER_AGENTS)
         ua=UserAgent()
         request.headers.setdefault("User-Agent",ua.random)

settints.py

 DOWNLOADER_MIDDLEWARES = {
       'LaGou.middlewares.RandomUserAgent': 1,
 #    'LaGou.middlewares.MyCustomDownloaderMiddleware': 543,
 }

更多访问地址：https://github.com/hellysmile/fake-useragent