python抓取网页编码问题

抓取的网页如果包含中文，那么正确打印和保存网页就需要解码和编码

import urllib

url = 'http://example.com/'
html = urllib.urlopen(url).read()
unicode = html.decode("utf-8")
gbkcode = unicode.encode("gbk")
print(gbkcode)
f = open("hello.txt", "w")
f.write(gbkcode)
f.close