python scrapy爬虫防止ip被封的实现方案

主要策略：

动态设置user agent
禁用cookies
设置延迟下载
使用google cache
使用IP地址池（Tor Project、VPN和代理IP）
使用Crawlera
1、创建middlewares.py

　　scrapy代理IP、user agent的切换都是通过DOWNLOADER_MIDDLEWARES进行控制，下面我们创建middlewares.py文件。

import random
import base64
from Questions.settings import PROXIES

class RandomUserAgent(object):
    """Randomly rotate user agents based on a list of predefined ones"""

    def __init__(self, agents):
        self.agents = agents

    @classmethod
    def from_crawler(cls, crawler):
        return cls(crawler.settings.getlist('USER_AGENTS'))

    def process_request(self, request, spider):
        #print "**************************" + random.choice(self.agents)
        request.headers.setdefault('User-Agent', random.choice(self.agents))

class ProxyMiddleware(object):
    def process_request(self, request, spider):
        proxy = random.choice(PROXIES)
        if proxy['user_pass'] is not None:
            request.meta['proxy'] = "http://%s" % proxy['ip_port']
            encoded_user_pass = base64.b64encode(proxy['user_pass'].encode('utf-8'))
            request.headers['Proxy-Authorization'] = 'Basic ' + encoded_user_pass.decode()
            print("**************ProxyMiddleware have pass************" + proxy['ip_port'])
        else:
            print("**************ProxyMiddleware no pass************" + proxy['ip_port'])
            request.meta['proxy'] = "http://%s" % proxy['ip_port']

类RandomUserAgent主要用来动态获取user agent，user agent列表USER_AGENTS在settings.py中进行配置。

类ProxyMiddleware用来切换代理，proxy列表PROXIES也是在settings.py中进行配置。

2、修改settings.py配置USER_AGENTS和PROXIES

　　a)：添加USER_AGENTS

USER_AGENTS = [
    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; AcooBrowser; .NET CLR 1.1.4322; .NET CLR 2.0.50727)",
    "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; Acoo Browser; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506)",
    "Mozilla/4.0 (compatible; MSIE 7.0; AOL 9.5; AOLBuild 4337.35; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)",
    "Mozilla/5.0 (Windows; U; MSIE 9.0; Windows NT 9.0; en-US)",
    "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 2.0.50727; Media Center PC 6.0)",
    "Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 1.0.3705; .NET CLR 1.1.4322)",
    "Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 5.2; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506.30)",
    "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN) AppleWebKit/523.15 (KHTML, like Gecko, Safari/419.3) Arora/0.3 (Change: 287 c9dfb30)",
    "Mozilla/5.0 (X11; U; Linux; en-US) AppleWebKit/527+ (KHTML, like Gecko, Safari/419.3) Arora/0.6",
    "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2pre) Gecko/20070215 K-Ninja/2.1.1",
    "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9) Gecko/20080705 Firefox/3.0 Kapiko/3.0",
    "Mozilla/5.0 (X11; Linux i686; U;) Gecko/20070322 Kazehakase/0.4.5",
    "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.8) Gecko Fedora/1.9.0.8-1.fc10 Kazehakase/0.5.6",
    "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11",
    "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_3) AppleWebKit/535.20 (KHTML, like Gecko) Chrome/19.0.1036.7 Safari/535.20",
    "Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; fr) Presto/2.9.168 Version/11.52",
]

b)：添加匿名代理IP设置PROXIES

PROXIES = [
    {'ip_port': '61.178.238.122:63000', 'user_pass': ''},
    {'ip_port': '117.114.149.66:53281', 'user_pass': ''},
    {'ip_port': '61.138.33.20:808', 'user_pass': ''},
    {'ip_port': '61.135.217.7:80', 'user_pass': ''},
    {'ip_port': '27.17.45.90:43411', 'user_pass': ''},
    {'ip_port': '118.122.92.252:37901', 'user_pass': ''},
    {'ip_port': '219.238.186.188:8118', 'user_pass': ''},
    {'ip_port': '61.164.39.69:53281', 'user_pass': ''},
    {'ip_port': '60.191.201.38:45461', 'user_pass': ''},
    {'ip_port': '113.108.242.36:47713', 'user_pass': ''},
    {'ip_port': '117.191.11.107:80', 'user_pass': ''},
    {'ip_port': '106.14.176.162:80', 'user_pass': ''},
    {'ip_port': '163.125.251.144:8118', 'user_pass': ''},
    {'ip_port': '119.179.137.217:8060', 'user_pass': ''},
    {'ip_port': '111.230.254.195:8118', 'user_pass': ''}
]

代理IP可以去网上搜，比较多。测试的时候有些IP不行就删掉。

c)：禁用cookies

COOKIES_ENABLED=False
d)：设置下载延迟

DOWNLOAD_DELAY=3
e)：最后设置DOWNLOADER_MIDDLEWARES，根据自己的项目名称设置

DOWNLOADER_MIDDLEWARES = {
    'Questions.middlewares.RandomUserAgent': 1,
    'scrapy.contrib.downloadermiddleware.httpproxy.HttpProxyMiddleware': 110,
    'Questions.middlewares.ProxyMiddleware': 100,
}

然后就OK了。