UA池和代理池

2. UA池：User-Agent池

- 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：

1.在下载中间件中拦截请求

2.将拦截到的请求的请求头信息中的UA进行篡改伪装

3.在配置文件中开启下载中间件

代码展示：

#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):
 ?
     def process_request(self, request, spider):
         #从列表中随机抽选出一个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)
 ?
 ?
 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"
 ]


3. 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。
- 操作流程：
 1.在下载中间件中拦截请求
 2.将拦截到的请求的IP修改成某一代理IP
 3.在配置文件中开启下载中间件
代码展示：

 #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):
     def process_request(self, request, spider):
         #对拦截到请求的url进行判断（协议头到底是http还是https）
         #request.url返回值：http://www.xxx.com
         h = request.url.split(‘:‘)[0]  #请求的协议头
         if h == ‘https‘:
             ip = random.choice(PROXY_https)
             request.meta[‘proxy‘] = ‘https://‘+ip
         else:
             ip = random.choice(PROXY_http)
             request.meta[‘proxy‘] = ‘http://‘ + ip
 ?
 #可被选用的代理IP
 PROXY_http = [
     ‘153.180.102.104:80‘,
     ‘195.208.131.189:56055‘,
 ]
 PROXY_https = [
     ‘120.83.49.90:9000‘,
     ‘95.189.112.214:35508‘,
 ]