如何建立爬蟲代理ip池

一、爲什麼需要建立爬蟲代理ip池
在衆多的網站防爬措施中，有一種是根據ip的訪問頻率進行限制的，在某段時間內，當某個ip的訪問量達到一定的閥值時， 該ip會被拉黑、在一段時間內被禁止訪問這種時候，可以通過降低爬蟲的頻率，或者更改ip來應對。後者就需要有一個可 用的代理ip池，以供爬蟲工作時切換。這個就是更換ip軟件。
二、如何建立一個爬蟲代理ip池
思路：
1、找到一個免費的ip代理網站(如：西刺代理)
2、爬取ip（常規爬取requests+BeautifulSoup）
3、驗證ip有效性（攜帶爬取到的ip，去訪問指定的url，看返回的狀態碼是不是200）
4、記錄ip （寫到文檔）
#!/usr/bin/env python3

-- coding: utf-8 --

import requests,threading,datetime
from bs4 import BeautifulSoup
import random
1、抓取西刺代理網站的代理ip
2、並根據指定的目標url,對抓取到ip的有效性進行驗證
3、最後存到指定的path
文檔處理

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

清空文檔

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

讀取文檔

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

計算時間差,格式: 時分秒

        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

返回一個隨機的請求頭 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

檢查ip是否可用

        def checkip(targeturl,ip):
            headers =getheaders()  # 定製請求頭
            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

獲取代理方法 免費代理 XiciDaili

        def findip(type,pagenum,targeturl,path): # ip類型,頁碼,目標url,存放ip的路徑
            list={'1': 'http://www.xicidaili.com/nt/', # xicidaili國內普通代理
                  '2': 'http://www.xicidaili.com/nn/', # xicidaili國內高匿代理
                  '3': 'http://www.xicidaili.com/wn/', # xicidaili國內https代理
                  '4': 'http://www.xicidaili.com/wt/'} # xicidaili國外http代理
            url=list[str(type)]+str(pagenum) # 配置url
            headers = getheaders() # 定製請求頭
            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)

多線程抓取ip入口

       def getip(targeturl,path):
         truncatefile(path) # 爬取前清空文檔
         start = datetime.datetime.now() # 開始時間
         threads=[]
         for type in range(4):   # 四種類型ip,每種類型取前三頁,共12條線程
             for pagenum in range(3):
                 t=threading.Thread(target=findip,args=(type+1,pagenum+1,targeturl,path))
                 threads.append(t)
         print('開始爬取代理ip')
         for s in threads: # 開啓多線程爬取
             s.start()
         for e in threads: # 等待所有線程結束
             e.join()
         print('爬取完成')
         end = datetime.datetime.now() # 結束時間
         diff = gettimediff(start, end)  # 計算耗時
         ips = read(path)  # 讀取爬到的ip數量
         print('一共爬取代理ip: %s 個,共耗時: %s \n' % (len(ips), diff))

啓動

           if __name__ == '__main__':
            path = 'ip.txt' # 存放爬取ip的文檔path
            targeturl = 'http://www.cnblogs.com/TurboWay/' # 驗證ip有效性的指定url
        getip(targeturl,path)  http網頁在線代理