Python base64编码

2019-11-11 02:13:40

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base64要求把每三个8bit的字节转换为四个6bit的字节(3*8=4*6)，然后把6bit的字节再添两位高位0，组成四个8bit字节，也就是说，转换后的字符串理论上将要比原来的长1/3。

1.base64编码

# -*- coding: utf-8 -*-import base64initial_data = open(__file__, 'rt').read()encoded_data = base64.b64encode(initial_data)PRint '%d bytes before encoding' % len(initial_data)print '%d bytes after encoding' % len(encoded_data)printprint encoded_data

输出：

260 bytes before encoding348 bytes after encodingIyAtKi0gY29kaW5nOiB1dGYtOCAtKi0KaW1wb3J0IGJhc2U2NAoKaW5pdGlhbF9kYXRhID0gb3BlbihfX2ZpbGVfXywgJ3J0JykucmVhZCgpCgplbmNvZGVkX2RhdGEgPSBiYXNlNjQuYjY0ZW5jb2RlKGluaXRpYWxfZGF0YSkKCnByaW50ICclZCBieXRlcyBiZWZvcmUgZW5jb2RpbmcnICUgbGVuKGluaXRpYWxfZGF0YSkKcHJpbnQgJyVkIGJ5dGVzIGFmdGVyIGVuY29kaW5nJyAlIGxlbihlbmNvZGVkX2RhdGEpCnByaW50CnByaW50IGVuY29kZWRfZGF0YQo=

2.base64解码

# -*- coding: utf-8 -*-import base64original_string = 'This is the data, in the clear.'print 'Original:', original_stringencoded_string = base64.b64encode(original_string)print 'Encoded:', encoded_stringdecoded_string = base64.b64decode(encoded_string)print 'Decoded:', decoded_string

输出：

Original: This is the data, in the clear.Encoded: VGhpcyBpcyB0aGUgZGF0YSwgaW4gdGhlIGNsZWFyLg==Decoded: This is the data, in the clear.

3.URL_Safe变体

默认的base64字母表可能会使用+和/，而这些字符可能出现在URL中，因此必须为这些字符指定可选择的编码情况，+由符号-来代替，而/由下划线_来代替，其他字母表不变。

# -*- coding: utf-8 -*-import base64for original in ['/xfb/xef', '/xff/xff']: print 'Original :', repr(original) print 'Standard encoding:', base64.standard_b64encode(original) print 'URL-safe encoding:', base64.urlsafe_b64encode(original) print

输出：

Original : '/xfb/xef'Standard encoding: ++8=URL-safe encoding: --8=Original : '/xff/xff'Standard encoding: //8=URL-safe encoding: __8=

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