计算文件MD5值-python

#coding=utf-8

import hashlib 

import sys 

def md5_calc(file):       

    md5_value=hashlib.md5()

    with open(file,'rb') as file_b:

        while True:

            data_flow=file_b.read(8096)      #每次读入8089kb进入内存

            if not data_flow:                #读取完后返回空值，False

                break

            md5_value.update(data_flow)

    file_b.close()

    return md5_value.hexdigest()

print(md5_calc(sys.argv[1]))