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。
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）
代码如下：
#!/usr/bin/env python3 # -*- coding: utf-8 -*- import requests,threading,datetime from bs4 import BeautifulSoup import random """ 1、抓取西刺代理网站的代理ip 2、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-------------------------------------------------------- # 写入文档 def write(path,text): with open(path,'a', encoding='utf-8') as f: f.writelines(text) f.write(' ') # 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 ' % (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)
结果：
