总结一下urllib2下载网页的三种方法

import urllib2
import cookielib

url = “http://www.baidu.com”

print ‘第一种下载网页的方法’
response1 = urllib2.urlopen(url)
print response1.getcode()
print len(response1.read())

print ‘第二种下载网页的方法’
request= urllib2.Request(url)
request.add_header(‘user-agent’,’xw’)
response2 = urllib2.urlopen(request)
print response2.getcode()
print len(response2.read())

print ‘第三种下载网页的方法’
cj = cookielib.CookieJar()
opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj))
urllib2.install_opener(opener)
response3 = urllib2.urlopen(url)
print response3.getcode()
print cj
print len(response3.read())