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 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)
执行结果：
$ python base64_urlsafe.py
Original: ’\xfb\xef’
Standardencoding: ++8=
URL-safeencoding: --8=
Original: ’\xff\xff’
Standardencoding: //8=
URL-safeencoding: __8=
__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.
