• python模块介绍 base64 使用ASCII编码二进制数据


    出自:http://blog.csdn.net/oychw/article/details/8920653

    2013-05-13 磁针石

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    #参考资料:《The PythonStandard Libraryby Example 2011》

          

           转换二进制数据为适合明文协议传输的ASCII序列。转换8bits为每个字节包含6,5或4bits的有效数据,比如SMTP,URL的一部分或者HTTPPOST的一部分。参考:RFC 3548。编码算法不同于uuencode。

           Base64编码:

    #end_pymotw_header

    import base64

    import textwrap

    # Load this source file and strip the header.

    with open(__file__, 'rt') as input:

        raw =input.read()

       initial_data = raw.split('#end_pymotw_header')[1]

    encoded_data = base64.b64encode(initial_data)

    num_initial = len(initial_data)

    # There will never be more than 2 padding bytes.

    padding = 3 - (num_initial % 3)

    print '%d bytes before encoding' % num_initial

    print 'Expect %d padding bytes' % padding

    print '%d bytes after encoding' % len(encoded_data)

    print

    print encoded_data

    执行结果:

    $ python base64_b64encode.py

    168 bytes before encoding

    Expect 3 padding bytes

    224 bytes after encoding

    CgppbXBvcnQgYmFzZTY0CmltcG9ydCB0ZXh0d3JhcAoKIyBMb2FkIHRoaXMgc291c

    mNlIGZpbGUgYW5kIHN0cmlwIHRoZSBoZWFkZXIuCndpdGggb3BlbihfX2ZpbGVfXy

    wgJ3J0JykgYXMgaW5wdXQ6CiAgICByYXcgPSBpbnB1dC5yZWFkKCkKICAgIGluaXR

    pYWxfZGF0YSA9IHJhdy5zcGxpdCgn

    b64decode()通过把4bytes转为3bytes实现解码。

    #end_pymotw_header

    import base64

    original_string = 'This is the data, in the clear.'

    print 'Original:', original_string

    encoded_string = base64.b64encode(original_string)

    print 'Encoded :', encoded_string

    decoded_string = base64.b64decode(encoded_string)

    print 'Decoded :', decoded_string

    执行结果:

    $ python base64_b64decode.py

    Original: This is the data, in the clear.

    Encoded : VGhpcyBpcyB0aGUgZGF0YSwgaW4gdGhlIGNsZWFyLg==

    Decoded : This is the data, in the clear.

    Base64默认会使用+和/, 但是这2个字符在url中也有特殊含义。使用urlsafe可以解决这个问题。这个2个字符会用下划线替换。

    #end_pymotw_header

    importbase64

    encodes_with_pluses= chr(251) + chr(239)

    encodes_with_slashes= chr(255) * 2

    fororiginal in [ encodes_with_pluses, encodes_with_slashes ]:

        print 'Original         :', repr(original)

        print 'Standard encoding:',base64.standard_b64encode(original)

        print 'URL-safe encoding:',base64.urlsafe_b64encode(original)

    print

                  执行结果:

                  $ python base64_urlsafe.py

    Original: ’\xfb\xef’

    Standardencoding: ++8=

    URL-safeencoding: --8=

    Original: ’\xff\xff’

    Standardencoding: //8=

    URL-safeencoding: __8=

    其他编码:Base32包含26个大写字母和2-7的数字。

    __version__= "$Id$"

    #end_pymotw_header

    importbase64

    original_string= 'This is the data, in the clear.'

    print'Original:', original_string

    encoded_string= base64.b32encode(original_string)

    print'Encoded :', encoded_string

    decoded_string= base64.b32decode(encoded_string)

    print'Decoded :', decoded_string

    执行结果:

    $python base64_base32.py

    Original:This is the data, in the clear.

    Encoded: KRUGS4ZANFZSA5DIMUQGIYLUMEWCA2LOEB2GQZJAMNWGKYLSFY======

    Decoded: This is the data, in the clear.

    其他编码:Base16包含16个16进制大写数字。

    __version__= "$Id$"

    #end_pymotw_header

    importbase64

    original_string= 'This is the data, in the clear.'

    print'Original:', original_string

    encoded_string= base64.b16encode(original_string)

    print'Encoded :', encoded_string

    decoded_string= base64.b16decode(encoded_string)

    print'Decoded :', decoded_string

    执行结果:

    $python base64_base16.py

    Original:This is the data, in the clear.

    Encoded: 546869732069732074686520646174612C20696E2074686520636C6561

    722E

    Decoded: This is the data, in the clear.

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  • 原文地址:https://www.cnblogs.com/mfryf/p/3090062.html
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