呈现一段最简单的代码：

import urllib.request

with urllib.request.urlopen('http://www.python.org/') as f:
    print(f.read().decode('utf-8'))

剩下的可以看官网

http://docs.python.org/3.3/library/urllib.html?highlight=urllib#urllib

更详细地可以看：

http://docs.python.org/3.3/library/urllib.request.html#module-urllib.request

21.5. urllib —
URL handling modules

urllib is a package that collects several modules
for working with URLs:

• urllib.request for
  opening and reading URLs
• urllib.error containing
  the exceptions raised by urllib.request
• urllib.parse for
  parsing URLs
• urllib.robotparser for
  parsing robots.txt files