UA池和ip代理池

UA池

背景

     我们在使用下载中间件处理请求,一般会对请求设置随机的User-Agent,设置随机的代理.目的就是防止爬取网站的反爬虫策略,但是同一类型User-Agent的浏览器还是容易被监测到,开启UA池放置更多类型的User-Agent就能够极大避免反扒机制

作用

　　- 尽可能多的将scrapy工程中的请求伪装成不同类型的浏览器身份

操作流程

• 在下载中间件中拦截请求
• 将拦截到的请求的请求头信息中的UA进行篡改伪装
• 在settings.py中开启下载中间件

具体代码

#导包
from scrapy.contrib.downloadermiddleware.useragent import UserAgentMiddleware
import random

#UA池代码的编写(单独给UA池封装一个下载中间件的一个类   )
class RandomUserAgent( UserAgentMiddleware):

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",
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.6 "
        "(KHTML, like Gecko) Chrome/20.0.1092.0 Safari/536.6",
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.6 "
        "(KHTML, like Gecko) Chrome/20.0.1090.0 Safari/536.6",
        "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.1 "
        "(KHTML, like Gecko) Chrome/19.77.34.5 Safari/537.1",
        "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.5 "
        "(KHTML, like Gecko) Chrome/19.0.1084.9 Safari/536.5",
        "Mozilla/5.0 (Windows NT 6.0) AppleWebKit/536.5 "
        "(KHTML, like Gecko) Chrome/19.0.1084.36 Safari/536.5",
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",
        "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_0) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1063.0 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1062.0 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1061.1 Safari/536.3",
        "Mozilla/5.0 (Windows NT 6.2) AppleWebKit/536.3 "
        "(KHTML, like Gecko) Chrome/19.0.1061.0 Safari/536.3",
        "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/535.24 "
        "(KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24",
        "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/535.24 "
        "(KHTML, like Gecko) Chrome/19.0.1055.1 Safari/535.24"
]

    def process_request(self,request,spider):
        #从列表中随机抽取一个ua值
         ua = random.choice(user_agent_list)
        #ua值进行当前拦截到请求的ua的写入操作
        request.headers.setdefault("User-Agent",ua)

 ip代理池

 作用

　　- 尽可能多的将scrapy工程中的请求的IP设置成不同的,防止被反扒策略封禁本机IP

操作流程

• 在下载中间件拦截请求
• 将拦截到的请求IP修改成某一代理ip
• 在settings.py中开启下载中间件

具体代码

"""批量对拦截到的请求进行ip更换"""
#单独封装下载中间件类

class Proxy(object):

#可被选用的代理IP
PROXY_http = [
    '126.120.102.124:80',
    '101.208.131.169:56055',
]
PROXY_https = [
    '20.83.49.90:900',
    '91.182.12.212:3508',
]
    
    def process_exception(self,request,spider):
        #针对拦截到的url进行判断,(协议头http/https的区分)
        #request.url 返回值处理为 http/https//:www.xxx.com
        h = request.url.split(':')[0]  #获取请求头协议
        if h == "https":
            ip.random.choice(Proxy_https)
            request.meta['proxy'] = 'https' + ip
        else:
            ip.random.choice(Proxy_http)
            request.meta['proxy'] = "http" + ip
　　　　　return request

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