urllib2下载器网页的三种方法

python网络爬虫第一步

#coding:utf8
import urllib2
import cookielib
url = 'http://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(cj)