什么是user-agent?
用户代理,服务器识别用户的操作系统,浏览器类型和渲染引擎,不同浏览器的user-agent是不同的
如何随机更改user-agent?
1. 在setting中添加user-agent列表
# setting:
# 随机更换user-agent
# USER_AGENT_LIST = ['zspider/0.9-dev http://feedback.redkolibri.com/',
# 'Xaldon_WebSpider/2.0.b1',
# 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) Speedy Spider (http://www.entireweb.com/about/search_tech/speedy_spider/)',
# 'Mozilla/5.0 (compatible; Speedy Spider; http://www.entireweb.com/about/search_tech/speedy_spider/)',
# 'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0) AddSugarSpiderBot www.idealobserver.com',
# ]
2. 在download_middleware中导入user-agent列表,每次列表中取得一个值
__author__ = 'beimenchuixue'
__blog__ = 'http://www.cnblogs.com/2bjiujiu/' from random import choice class RandomUserAgentMiddleware(object): def __init__(self, agent_list):
super(RandomUserAgentMiddleware, self).__init__()
self.agent_list = agent_list @classmethod
def from_crawler(cls, crawler):
# 获取USER_AGENT_LIST列表
o = crawler.settings['USER_AGENT_LIST']
return cls(o) def process_request(self, request, spider):
if self.agent_list:
# 随机取得一个值
random_user_agent = choice(self.agent_list)
# 设置User-Agent值
request.headers.setdefault(b'User-Agent', random_user_agent)
3. setting中注册download_middleware,把原生的置为None
DOWNLOADER_MIDDLEWARES = {
'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware': None,
'JobBole.middlewares.RandomUserAgentMiddleware': 400, }
download_middleware类有什么用?
他是介于request和response中的钩子框架,用来全局修改request和response
还有哪些更改随机user-agent方法?
scrapy-fake-useragent -- Githup直接搜索