一、为什么需要建立爬虫代理ip池

在众多的网站防爬措施中，有一种是根据ip的访问频率进行限制的，在某段时间内，当某个ip的访问量达到一定的阀值时， 该ip会被拉黑、在一段时间内被禁止访问这种时候，可以通过降低爬虫的频率，或者更改ip来应对。后者就需要有一个可 用的代理ip池，以供爬虫工作时切换。这个就是更换ip软件。二、如何建立一个爬虫代理ip池思路：1、找到一个免费的ip代理网站(如：西刺代理)2、爬取ip（常规爬取requests+BeautifulSoup）3、验证ip有效性（携带爬取到的ip，去访问指定的url，看返回的状态码是不是200）4、记录ip （写到文档）#!/usr/bin/env python3

-- coding: utf-8 --

import requests,threading,datetime

from bs4 import BeautifulSoupimport random1、抓取西刺代理网站的代理ip2、并根据指定的目标url,对抓取到ip的有效性进行验证3、最后存到指定的path文档处理

def write(path,text):         with open(path,'a', encoding='utf-8') as f:                 f.writelines(text)                 f.write('\n')

清空文档

def truncatefile(path):         with open(path, 'w', encoding='utf-8') as f:                 f.truncate()

读取文档

def read(path):            with open(path, 'r', encoding='utf-8') as f:                txt = []                for s in f.readlines():                    txt.append(s.strip())            return txt

计算时间差,格式: 时分秒

def gettimediff(start,end):            seconds = (end - start).seconds            m, s = divmod(seconds, 60)            h, m = divmod(m, 60)            diff = ("%02d:%02d:%02d" % (h, m, s))            return diff

返回一个随机的请求头 headers

def getheaders():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"            ]        UserAgent=random.choice(user_agent_list)        headers = {'User-Agent': UserAgent}        return headers

检查ip是否可用

def checkip(targeturl,ip):            headers =getheaders()  # 定制请求头            proxies = {"http": "http://"+ip, "https": "http://"+ip}  # 代理ip            try:                response=requests.get(url=targeturl,proxies=proxies,headers=headers,timeout=5).status_code                if response == 200 :                    return True                else:                    return False            except:                return False

获取代理方法 免费代理 XiciDaili

def findip(type,pagenum,targeturl,path): # ip类型,页码,目标url,存放ip的路径            list={'1': 'http://www.xicidaili.com/nt/', # xicidaili国内普通代理                  '2': 'http://www.xicidaili.com/nn/', # xicidaili国内高匿代理                  '3': 'http://www.xicidaili.com/wn/', # xicidaili国内https代理                  '4': 'http://www.xicidaili.com/wt/'} # xicidaili国外http代理            url=list[str(type)]+str(pagenum) # 配置url            headers = getheaders() # 定制请求头            html=requests.get(url=url,headers=headers,timeout = 5).text            soup=BeautifulSoup(html,'lxml')            all=soup.find_all('tr',class_='odd')            for i in all:                t=i.find_all('td')                ip=t[1].text+':'+t[2].text                is_avail = checkip(targeturl,ip)                if is_avail == True:                    write(path=path,text=ip)                    print(ip)

多线程抓取ip入口

def getip(targeturl,path):         truncatefile(path) # 爬取前清空文档         start = datetime.datetime.now() # 开始时间         threads=[]         for type in range(4):   # 四种类型ip,每种类型取前三页,共12条线程             for pagenum in range(3):                 t=threading.Thread(target=findip,args=(type+1,pagenum+1,targeturl,path))                 threads.append(t)         print('开始爬取代理ip')         for s in threads: # 开启多线程爬取             s.start()         for e in threads: # 等待所有线程结束             e.join()         print('爬取完成')         end = datetime.datetime.now() # 结束时间         diff = gettimediff(start, end)  # 计算耗时         ips = read(path)  # 读取爬到的ip数量         print('一共爬取代理ip: %s 个,共耗时: %s \n' % (len(ips), diff))

启动

if __name__ == '__main__':            path = 'ip.txt' # 存放爬取ip的文档path            targeturl = 'http://www.cnblogs.com/TurboWay/' # 验证ip有效性的指定url        getip(targeturl,path)  http网页在线代理