Scrapy设置随机请求头

Scrapy设置随机请求头

基本介绍

设置随机请求头是应对反爬虫的一种手段，如果某个相同的请求头对目标网站频繁进行访问，可能会被封禁。
故此我们在爬虫的时候最好随机更改我们的请求头，我将在Scrapy的下载器中间件上进行随机更改请求头

常见备选请求头User-Agent

Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.1 (KHTML, like Gecko) Chrome/14.0.835.163 Safari/535.1
 
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0) Gecko/20100101 Firefox/6.0
 
Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.50 (KHTML, like Gecko) Version/5.1 Safari/534.50

Opera/9.80 (Windows NT 6.1; U; zh-cn) Presto/2.9.168 Version/11.50
 
Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0; .NET CLR 2.0.50727; SLCC2; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.3; .NET4.0C; Tablet PC 2.0; .NET4.0E)
 
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; InfoPath.3)
 
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB7.0)
 
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)

Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)
 
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.3; .NET4.0C; .NET4.0E)
 
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.3; .NET4.0C; .NET4.0E; SE 2.X MetaSr 1.0)
 
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.3 (KHTML, like Gecko) Chrome/6.0.472.33 Safari/534.3 SE 2.X MetaSr 1.0
 
Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.3; .NET4.0C; .NET4.0E)
 
Mozilla/5.0 (Windows NT 6.1) AppleWebKit/535.1 (KHTML, like Gecko) Chrome/13.0.782.41 Safari/535.1 QQBrowser/6.9.11079.201

Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.3; .NET4.0C; .NET4.0E) QQBrowser/6.9.11079.201
 
Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)

编写下载器中间件

我们选择重写我们的下载器中间件类，在middlewares.py中添加如下代码

class RandomUserAgentMiddleWare(object): 
	USER_AGENT_LIST = [   
		"Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0) Gecko/20100101 Firefox/6.0",        		 "Opera/9.80 (Windows NT 6.1; U; zh-cn) Presto/2.9.168 Version/11.50"
		"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)"    ] 
	def process_request(self,request,spider):  
		user_agent = random.choice(self.USER_AGENT_LIST)  
		request.heardes['User-Agent'] = user_agent

Setting.py的配置

在setting.py中找到这段注释，并将蓝色部分换成我们刚写好的类

再去运行我们的爬虫，爬虫就会生成随机请求头去访问我们的目标网站