文件的md5计算

 1 def GetFileMd5(filename):
 2      if not os.path.isfile(filename):
 3          return
 4      myhash = hashlib.md5()
 5      with open(filename,'rb') as f:
 6          while True:
 7              b = f.read(8096)
 8              if not b :
 9                  break
10              myhash.update(b)
11              return myhash.hexdigest()