python下载文件的三种方法

Python开发中时长遇到要下载文件的情况，最常用的方法就是通过Http利用urllib或者urllib2模块。

当然你也可以利用ftplib从ftp站点下载文件。此外Python还提供了另外一种方法requests。

下面来看看三种方法是如何来下载zip文件的：

    import urllib 
    import urllib2 
    import requests
    print "downloading with urllib" 
    url = 'http://www.pythontab.com/test/demo.zip'  
    print "downloading with urllib"
    urllib.urlretrieve(url, "demo.zip")
    import urllib2
    print "downloading with urllib2"
    url = 'http://www.pythontab.com/test/demo.zip' 
    f = urllib2.urlopen(url) 
    data = f.read() 
    with open("demo2.zip", "wb") as code:     
        code.write(data)
    import requests 
    print "downloading with requests"
    url = 'http://www.pythontab.com/test/demo.zip' 
    r = requests.get(url) 
    with open("demo3.zip", "wb") as code:
         code.write(r.content)
看起来使用urllib最为简单，一句语句即可。当然你可以把urllib2缩写成：
  f = urllib2.urlopen(url)