Python通过文件路径计算文件Hash值的方法

import hashlib
import os,sys
def CalcSha1(filepath):
  with open(filepath,'rb') as f:
    sha1obj = hashlib.sha1()
    sha1obj.update(f.read())
    hash = sha1obj.hexdigest()
    print(hash)
    return hash
def CalcMD5(filepath):
  with open(filepath,'rb') as f:
    md5obj = hashlib.md5()
    md5obj.update(f.read())
    hash = md5obj.hexdigest()
    print(hash)
    return hash
if __name__ == "__main__":
  if len(sys.argv)==2 :
    hashfile = sys.argv[1]
    if not os.path.exists(hashfile):
      hashfile = os.path.join(os.path.dirname(__file__),hashfile)
      if not os.path.exists(hashfile):
        print("cannot found file")
      else
      CalcMD5(hashfile)
  else:
    CalcMD5(hashfile)
    #raw_input("pause")
else:
  print("no filename")