Python使用urllib2模块实现断点续传下载的方法

#!/usr/bin/python 
# -*- coding: UTF-8 -* 
''' 
Created on 2013-04-15 
Created by RobinTang 
A demo for Resuming Transfer 
''' 
import urllib2 
req = urllib2.Request('http://www.python.org/') 
req.add_header('Range', 'bytes=0-20')
# set the range, from 0byte to 19byte, 20bytes len 
res = urllib2.urlopen(req) 
data = res.read() 
print data 
print '---------' 
print 'len:%d'%len(data)