参考博客:https://www.cnblogs.com/xingh/p/6937353.html
import os
files = os.listdir("D:/ruanjianxiazai/tuxiangyangben/fengehou/train")#列出当前目录下所有的文件
for filename in files:
portion = os.path.splitext(filename)#分离文件名字和后缀
# print(portion)
if portion[1] ==".png":#根据后缀来修改,如无后缀则空
newname = portion[0]+".jpg"#要改的新后缀
os.chdir("D:/ruanjianxiazai/tuxiangyangben/fengehou/train")#切换文件路径,如无路径则要新建或者路径同上,做好备份
os.rename(filename,newname)