Python计算文件的MD5

John Doe at 2012-05-15 under python md5 hash

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下面两个函数，一个用于计算字符串的MD5，另一个用于计算指定文件的MD5

# -*- coding: utf-8 -*-

import hashlib


def md5hex(word):
    """ MD5加密算法，返回32位小写16进制符号 """
    if isinstance(word, unicode):
        word = word.encode("utf-8")
    elif not isinstance(word, str):
        word = str(word)
    m = hashlib.md5()
    m.update(word)
    return m.hexdigest()


def md5sum(fname):
    """ 计算文件的MD5值 """
    def read_chunks(fh):
        fh.seek(0)
        chunk = fh.read(8096)
        while chunk:
            yield chunk
            chunk = fh.read(8096)
        else: #最后要将游标放回文件开头
            fh.seek(0)
    m = hashlib.md5()
    if isinstance(fname, basestring) \
            and os.path.exists(fname):
        with open(fname, "rb") as fh:
            for chunk in read_chunks(fh):
                m.update(chunk)
    #上传的文件缓存 或 已打开的文件流
    elif fname.__class__.__name__ in ["StringIO", "StringO"] \
                or isinstance(fname, file):
        for chunk in read_chunks(fname):
            m.update(chunk)
    else:
        return ""
    return m.hexdigest()

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