arcpy 批量修改文件名

import arcpy
import os
import re

from os.path import join, getsize

def getFile(filepath,ext):
    arcpy.env.workspace = filepath
    return arcpy.ListFiles("*"+ext)
def getmxdfile(workspace,ext):
    FileList=[]
    for dirpath, dirnames, filenames in os.walk(workspace):
        for filename in filenames:
            #arcpy.AddMessage("filename=="+filename)

            if filename.lower().endswith(ext):
                fullfile=os.path.join(dirpath, filename)
                arcpy.AddMessage(fullfile)
                FileList.append(fullfile)
    return FileList

inpath  = arcpy.GetParameterAsText(0)
oldname = arcpy.GetParameterAsText(1)
newname = arcpy.GetParameterAsText(2)
mydir = inpath
a=getmxdfile(mydir,".tbx")

for b in a:

    #arcpy.AddMessage("mxd="+str(mxd))
    if b.find(oldname)>-1:
        arcpy.AddMessage(b)
        newFile=b.replace(oldname,newname)
        arcpy.AddMessage("old:"+newFile)
        try:
            os.rename(b,  newFile)

        except Exception as e:
              print(e.message)
              # If using this code within a script tool, AddError c  an be used to return messages
              #   back to a script tool.  If not, AddError will have no effect.
              arcpy.AddError(e.message)