python文件取MD5

import hashlib

def md5sum(filename, blocksize=65536):

	hash = hashlib.md5()

	with open(filename, "rb") as f:

		#必须是rb形式打开的，否则的两次出来的结果不一致

		for block in iter(lambda: f.read(blocksize), b""):

			hash.update(block)

	return hash.hexdigest()