用python登录页面

import urllib2,cookielib

cookie=cookielib.CookieJar()
opener=urllib2.build_opener(urllib2.HTTPCookieProcessor(cookie))
urllib2.install_opener(opener)

user=raw_input('帐号:')
mm=raw_input('密码:')

postdata=urllib.urlencode({'username':user,'password':mm,'roleid':'4'})
login_response= urllib2.urlopen('url' ,postdata)