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('\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.cdsy.xyz/computer/' # 验证ip有效性的指定url
- getip(targeturl,path)
结果: