使用urllib2，太强大了
试了下用代理登陆拉取cookie，跳转抓图片……
文档：http://docs.python.org/library/urllib2.html

直接上demo代码了
包括：直接拉取，使用Reuqest(post/get),使用代理，cookie,跳转处理

#!/usr/bin/python
# -*- coding:utf-8 -*-
# urllib2_test.py
# author: wklken
# 2012-03-17 wklken@yeah.net


import urllib,urllib2,cookielib,socket

url = \"http://www.testurl.....\" #change yourself
#最简单方式
def use_urllib2():
 try:
  f = urllib2.urlopen(url, timeout=5).read()
 except urllib2.URLError, e:
  print e.reason
 print len(f)

#使用Request
def get_request():
 #可以设置超时
 socket.setdefaulttimeout(5)
 #可以加入参数 [无参数，使用get，以下这种方式，使用post]
 params = {\"wd\":\"a\",\"b\":\"2\"}
 #可以加入请求头信息，以便识别
 i_headers = {\"User-Agent\": \"Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.1) Gecko/20090624 Firefox/3.5\",
       \"Accept\": \"text/plain\"}
 #use post,have some params post to server,if not support ,will throw exception
 #req = urllib2.Request(url, data=urllib.urlencode(params), headers=i_headers)
 req = urllib2.Request(url, headers=i_headers)

 #创建request后，还可以进行其他添加,若是key重复，后者生效
 #request.add_header(\'Accept\',\'application/json\')
 #可以指定提交方式
 #request.get_method = lambda: \'PUT\'
 try:
  page = urllib2.urlopen(req)
  print len(page.read())
  #like get
  #url_params = urllib.urlencode({\"a\":\"1\", \"b\":\"2\"})
  #final_url = url + \"?\" + url_params
  #print final_url
  #data = urllib2.urlopen(final_url).read()
  #print \"Method:get \", len(data)
 except urllib2.HTTPError, e:
  print \"Error Code:\", e.code
 except urllib2.URLError, e:
  print \"Error Reason:\", e.reason

def use_proxy():
 enable_proxy = False
 proxy_handler = urllib2.ProxyHandler({\"http\":\"http://proxyurlXXXX.com:8080\"})
 null_proxy_handler = urllib2.ProxyHandler({})
 if enable_proxy:
  opener = urllib2.build_opener(proxy_handler, urllib2.HTTPHandler)
 else:
  opener = urllib2.build_opener(null_proxy_handler, urllib2.HTTPHandler)
 #此句设置urllib2的全局opener
 urllib2.install_opener(opener)
 content = urllib2.urlopen(url).read()
 print \"proxy len:\",len(content)

class NoExceptionCookieProcesser(urllib2.HTTPCookieProcessor):
 def http_error_403(self, req, fp, code, msg, hdrs):
  return fp
 def http_error_400(self, req, fp, code, msg, hdrs):
  return fp
 def http_error_500(self, req, fp, code, msg, hdrs):
  return fp

def hand_cookie():
 cookie = cookielib.CookieJar()
 #cookie_handler = urllib2.HTTPCookieProcessor(cookie)
 #after add error exception handler
 cookie_handler = NoExceptionCookieProcesser(cookie)
 opener = urllib2.build_opener(cookie_handler, urllib2.HTTPHandler)
 url_login = \"https://www.yourwebsite/?login\"
 params = {\"username\":\"user\",\"password\":\"111111\"}
 opener.open(url_login, urllib.urlencode(params))
 for item in cookie:
  print item.name,item.value
 #urllib2.install_opener(opener)
 #content = urllib2.urlopen(url).read()
 #print len(content)
#得到重定向 N 次以后最后页面URL
def get_request_direct():
 import httplib
 httplib.HTTPConnection.debuglevel = 1
 request = urllib2.Request(\"http://www.google.com\")
 request.add_header(\"Accept\", \"text/html,*/*\")
 request.add_header(\"Connection\", \"Keep-Alive\")
 opener = urllib2.build_opener()
 f = opener.open(request)
 print f.url
 print f.headers.dict
 print len(f.read())

if __name__ == \"__main__\":
 use_urllib2()
 get_request()
 get_request_direct()
 use_proxy()
 hand_cookie()