一、普通抓取（这里演示的是抓取百度首页的相关代码，包括css和js）
#!/usr/bin/env python # -*- coding: utf-8 -*- import urllib2 def clear(): '''该函数用于清屏 ''' print(u'内容较多，显示3秒后翻页') time.sleep(3) OS = platform.system() if (OS == u'Windows'): os.system('cls') else: os.system('clear') def linkBaidu(): url = 'http://www.baidu.com' try: response = urllib2.urlopen(url, timeout=3) except urllib2.URLError: print(u"网络地址错误") exit() with open('./baidu.txt', 'w') as fp: fp.write(response.read()) print(u"获取url信息，response.geturl() \n: %s" % response.geturl()) print(u"获取返回代码，response.getcode() \n: %s" % response.getcode()) print(u"获取返回信息，response.info() \n: %s" % response.info()) print(u"获取的网页内容已存入当前目录的baidu.txt中，请自行查看") if __name__ == '__main__': linkBaidu() 二、通过代理（免费proxy）爬取，与第一点相比的好处就是不太容易被封住，或者说封住后可以换） #!/usr/bin/env python # -*- coding: utf-8 -*- import urllib2 import sys import re def testArgument(): '''测试输入参数，只需要一个参数 ''' if len(sys.argv) != 2: print(u'只需要一个参数就够了') tipUse() exit() else: TP = TestProxy(sys.argv[1]) def tipUse(): '''显示提示信息 ''' print(u'该程序只能输入一个参数，这个参数必须是一个可用的proxy') # 一下两句是命令行中的用法案例，先是python然后是文件名最后是代理ip地址 print(u'usage: python testUrllib2WithProxy.py http://1.2.3.4:5') print(u'usage: python testUrllib2WithProxy.py https://1.2.3.4:5') class TestProxy(object): '''这个类的作用是测试proxy是否有效 ''' def __init__(self, proxy): self.proxy = proxy self.checkProxyFormat(self.proxy) self.url = 'http://www.baidu.com' self.timeout = 5 self.flagWord = '百度' # 在网页返回的数据中查找这个关键词 self.useProxy(self.proxy) def checkProxyFormat(self, proxy): try: proxyMatch = re.compile('http[s]?://[\d]{1,3}\.[\d]{1,3}\.[\d]{1,3}\.[\d]{1,3}:[\d]{1,5}$') re.search(proxyMatch, proxy).group() except AttributeError: tipUse() exit() flag = 1 proxy = proxy.replace('//', '') try: protocol = proxy.split(':')[0] ip = proxy.split(':')[1] port = proxy.split(':')[2] except IndexError: print(u'下标出界') tipUse() exit() flag = flag and len(proxy.split(':')) == 3 and len(ip.split('.')) == 4 flag = ip.split('.')[0] in map(str, xrange(1, 256)) and flag flag = ip.split('.')[1] in map(str, xrange(256)) and flag flag = ip.split('.')[2] in map(str, xrange(256)) and flag flag = ip.split('.')[3] in map(str, xrange(1, 255)) and flag flag = protocol in [u'http', u'https'] and flag flag = port in map(str, range(1, 65535)) and flag '''这里是在检查proxy的格式 ''' if flag: print(u'输入的http代理服务器符合标准') else: tipUse() exit() def useProxy(self, proxy): '''利用代理访问百度，并查找关键词 ''' protocol = proxy.split('//')[0].replace(':', '') ip = proxy.split('//')[1] opener = urllib2.build_opener(urllib2.ProxyHandler({protocol: ip})) urllib2.install_opener(opener) try: response = urllib2.urlopen(self.url, timeout=self.timeout) except: print(u'连接错误，退出程序') exit() str = response.read() if re.search(self.flagWord, str): print(u'已取得特征词，该代理可用') else: print(u'该代理不可用') if __name__ == '__main__': testArgument() 三、用的网站会验证你是机器人还是人，所以第三种方法是赋予爬虫一个浏览器的header来冒充人先给出常用header的python包：userAgents
#!/usr/bin/env python #-*- coding: utf-8 -*- pcUserAgent = { "safari 5.1 – MAC":"User-Agent:Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_8; en-us) AppleWebKit/534.50 (KHTML, like Gecko) Version/5.1 Safari/534.50", "safari 5.1 – Windows":"User-Agent:Mozilla/5.0 (Windows; U; Windows NT 6.1; en-us) AppleWebKit/534.50 (KHTML, like Gecko) Version/5.1 Safari/534.50", "IE 9.0":"User-Agent:Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0);", "IE 8.0":"User-Agent:Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0)", "IE 7.0":"User-Agent:Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)", "IE 6.0":"User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)", "Firefox 4.0.1 – MAC":"User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0.1) Gecko/20100101 Firefox/4.0.1", "Firefox 4.0.1 – Windows":"User-Agent:Mozilla/5.0 (Windows NT 6.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1", "Opera 11.11 – MAC":"User-Agent:Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; en) Presto/2.8.131 Version/11.11", "Opera 11.11 – Windows":"User-Agent:Opera/9.80 (Windows NT 6.1; U; en) Presto/2.8.131 Version/11.11", "Chrome 17.0 – MAC":"User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_0) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11", "Maxthon":"User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Maxthon 2.0)", "Tencent TT":"User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; TencentTraveler 4.0)", "The World 2.x":"User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)", "The World 3.x":"User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; The World)", "sogou 1.x":"User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; SE 2.X MetaSr 1.0; SE 2.X MetaSr 1.0; .NET CLR 2.0.50727; SE 2.X MetaSr 1.0)", "360":"User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; 360SE)", "Avant":"User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Avant Browser)", "Green Browser":"User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)" } mobileUserAgent = { "iOS 4.33 – iPhone":"User-Agent:Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5", "iOS 4.33 – iPod Touch":"User-Agent:Mozilla/5.0 (iPod; U; CPU iPhone OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5", "iOS 4.33 – iPad":"User-Agent:Mozilla/5.0 (iPad; U; CPU OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5", "Android N1":"User-Agent: Mozilla/5.0 (Linux; U; Android 2.3.7; en-us; Nexus One Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1", "Android QQ":"User-Agent: MQQBrowser/26 Mozilla/5.0 (Linux; U; Android 2.3.7; zh-cn; MB200 Build/GRJ22; CyanogenMod-7) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1", "Android Opera ":"User-Agent: Opera/9.80 (Android 2.3.4; Linux; Opera Mobi/build-1107180945; U; en-GB) Presto/2.8.149 Version/11.10", "Android Pad Moto Xoom":"User-Agent: Mozilla/5.0 (Linux; U; Android 3.0; en-us; Xoom Build/HRI39) AppleWebKit/534.13 (KHTML, like Gecko) Version/4.0 Safari/534.13", "BlackBerry":"User-Agent: Mozilla/5.0 (BlackBerry; U; BlackBerry 9800; en) AppleWebKit/534.1+ (KHTML, like Gecko) Version/6.0.0.337 Mobile Safari/534.1+", "WebOS HP Touchpad":"User-Agent: Mozilla/5.0 (hp-tablet; Linux; hpwOS/3.0.0; U; en-US) AppleWebKit/534.6 (KHTML, like Gecko) wOSBrowser/233.70 Safari/534.6 TouchPad/1.0", "Nokia N97":"User-Agent: Mozilla/5.0 (SymbianOS/9.4; Series60/5.0 NokiaN97-1/20.0.019; Profile/MIDP-2.1 Configuration/CLDC-1.1) AppleWebKit/525 (KHTML, like Gecko) BrowserNG/7.1.18124", "Windows Phone Mango":"User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows Phone OS 7.5; Trident/5.0; IEMobile/9.0; HTC; Titan)", "UC":"User-Agent: UCWEB7.0.2.37/28/999", "UC standard":"User-Agent: NOKIA5700/ UCWEB7.0.2.37/28/999", "UCOpenwave":"User-Agent: Openwave/ UCWEB7.0.2.37/28/999", "UC Opera":"User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; ) Opera/UCWEB7.0.2.37/28/999" } 然后是修改header版爬虫 #!/usr/bin/env python # -*- coding: utf-8 -*- import urllib2 import userAgents '''userAgents.py是个自定义的模块，位置处于当前目录下 ''' class Urllib2ModifyHeader(object): '''使用urllib2模块修改header ''' def __init__(self): # 这个是PC + IE 的User-Agent PIUA = userAgents.pcUserAgent.get('IE 9.0') # 这个是Mobile + UC的User-Agent MUUA = userAgents.mobileUserAgent.get('UC standard') # 测试用的网站选择的是有道翻译 self.url = 'http://fanyi.youdao.com' self.useUserAgent(PIUA, 1) self.useUserAgent(MUUA, 2) def useUserAgent(self, userAgent, name): request = urllib2.Request(self.url) request.add_header(userAgent.split(':')[0], userAgent.split(':')[1]) response = urllib2.urlopen(request) fileName = str(name) + '.html' with open(fileName, 'a') as fp: fp.write("%s\n\n" % userAgent) fp.write(response.read()) if __name__ == '__main__': umh = Urllib2ModifyHeader()资料摘自 python网络爬虫实战
