很多网站使用cookie在本地硬盘中存储各种信息。可能想要查看cookie中保存的信息，或者使用cookie自动登录网站。
我们要记下表单中几个字段的ID，然后决定提交哪些虚拟值。我们首先要访问登录页面，再访问首页，查看在cookie中保存了什么。

import cookielib 
import urllib 
import urllib2 
ID_USERNAME = 'id_username' 
ID_PASSWORD = 'id_password' 
USERNAME = 'you@email.com' 
PASSWORD = 'mypassword' 
LOGIN_URL = 'https://bitbucket.org/account/signin/?next=/' 
NORMAL_URL = 'https://bitbucket.org/' 
def extract_cookie_info(): 
	# setup cookie jar 
	cj = cookielib.CookieJar() 
	login_data = urllib.urlencode({ ID_USERNAME : USERNAME, ID_PASSWORD : PASSWORD}) 
	# create url opener 
	opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj)) 
	resp = opener.open(LOGIN_URL, login_data) 
	# send login info 
	for cookie in cj: 
		print("----First time cookie: {} --> {}".format(cookie.name, cookie.value))
	print("Headers: {}".format(resp.headers))
	# now access without any login info 
	resp = opener.open(NORMAL_URL) 
	for cookie in cj: 
		print("++++Second time cookie: {} --> {}".format(cookie.name, cookie.value))
	print("Headers: {}".format(resp.headers))
if __name__ == '__main__': 
	extract_cookie_info()