python对url格式解析的方法

from urlparse import urlparse
url_str = "http://www.163.com/mail/index.htm"
url = urlparse(url_str)
print 'protocol:',url.scheme
print 'hostname:',url.hostname
print 'port:',url.port
print 'path:',url.path
print 'query:'url.query #查询参数，格式a=1
i = len(url.path) - 1
while i > 0:
  if url.path[i] == '/':
    break
  i = i - 1
print 'filename:',url.path[i+1:len(url.path)]