urllib2下载器网页的三种方法

python网络爬虫第一步：

coding:utf8import urllib2import cookieliburl = 'https://www.baidu.com/'print("第一种方法")response1 = urllib2.urlopen(url)print response1.getcode()print len(response1.read())print("第二种方法")request = urllib2.Request(url)request.add_header('user-agent','Mozilla/5.0')response2 = urllib2.urlopen(request)print response2.getcode()print len(response2.read())print("第三种方法")cj = cookielib.CookieJar()opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj))urllib2.install_opener(opener)response3 = urllib2.urlopen(url)print cjprint response3.getcode()print response3.read()