修改文件后缀名的python，第一次写，想必肯定有更简单的方法，求指点

import os
import string
dirName = "./code/demo/"
li=os.listdir(dirName)
for filename in li:
newname = filename
newname = newname.split(".")
if newname[-1]=="txt":
newname[-1]="html"
newname = string.join(newname,".")
filename = dirName+filename
newname = dirName+newname
os.rename(filename,newname)
print newname,"updated successfully"

顺便问句，怎么发帖就要花分数啊？。。。郁闷
[解决办法]
str = "hello.txt"
print str.endswith(".txt")
print str.replace(".txt",".html")