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如何让你的scrapy爬虫不再被ban
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前面用scrapy编写爬虫抓取了自己博客的内容并保存成json格式的数据（scrapy爬虫成长日记之创建工程-抽取数据-保存为json格式的数据）和写入数据库（scrapy爬虫成长日记之将抓取内容写入mysql数据库）。然而，这个爬虫的功能还是过于弱小，一旦目标网站设置了爬虫的限制，我们的爬虫也就失效了。因此这里重点讲述一下如何避免scrapy爬虫被ban。本门的所有内容都是基于前面两篇文章的基础上完成的，如果您错过了可以点击此回看：scrapy爬虫成长日记之创建工程-抽取数据-保存为json格式的数据，scrapy爬虫成长日记之将抓取内容写入mysql数据库
根据scrapy官方文档：http://doc.scrapy.org/en/master/topics/practices.html#avoiding-getting-banned里面的描述，要防止scrapy被ban，主要有以下几个策略。
- 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
由于Google cache受国内网络的影响，你懂得；Crawlera的分布式下载，我们可以在下次用一篇专门的文章进行讲解。所以本文主要从动态随机设置user agent、禁用cookies、设置延迟下载和使用代理IP这几个方式。好了，入正题：
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。
[root@bogon cnblogs]# vi cnblogs/middlewares.pyimport random
import base64
from settings import PROXIESclass 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.encodestring(proxy['user_pass'])
request.headers['Proxy-Authorization'] = 'Basic ' + encoded_user_pass
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)：添加代理IP设置PROXIES
PROXIES = [
{'ip_port': '111.11.228.75:80', 'user_pass': ''},
{'ip_port': '120.198.243.22:80', 'user_pass': ''},
{'ip_port': '111.8.60.9:8123', 'user_pass': ''},
{'ip_port': '101.71.27.120:80', 'user_pass': ''},
{'ip_port': '122.96.59.104:80', 'user_pass': ''},
{'ip_port': '122.224.249.122:8088', 'user_pass': ''},
]
代理IP可以网上搜索一下，上面的代理IP获取自：http://www.xici.net.co/。
c)：禁用cookies
COOKIES_ENABLED=False
d)：设置下载延迟
DOWNLOAD_DELAY=3
e)：最后设置DOWNLOADER_MIDDLEWARES
DOWNLOADER_MIDDLEWARES = {
# 'cnblogs.middlewares.MyCustomDownloaderMiddleware': 543,
'cnblogs.middlewares.RandomUserAgent': 1,
'scrapy.contrib.downloadermiddleware.httpproxy.HttpProxyMiddleware': 110,
#'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware': 110,
'cnblogs.middlewares.ProxyMiddleware': 100,
}
保存settings.py
3、测试
[root@bogon cnblogs]# scrapy crawl CnblogsSpider
源码更新至此：https://github.com/jackgitgz/CnblogsSpider
篇外话：本文的user agent和proxy列表都是采用settings.py的方式进行设置的，实际生产中user agent和proxy有可能会经常更新，每次更改配置文件显得很笨拙也不便于管理。因而，可以根据需要保存在mysql数据库。
