python2与python3下的base64模块

Python2的编解码

python2中程序数据类型默认为ASCII，所以需要先将数据解码（decode）成为Unicode类型，然后再编码（encode）成为想要转换的数据类型（gbk，utf-8，gb18030，gb2312），然后再解码成为对应的数据类型显示在屏幕上；

Python3的编解码

python3中程序默认数据类型为Unicode，所以直接将数据编码（encode）成为想要转换的数据类型（gbk，utf-8，gb18030，gb2312），然后解码成为对应的数据类型显示在屏幕上。

base64

Base64编码是一种“防君子不防小人”的编码方式。广泛应用于MIME协议，作为电子邮件的传输编码，生成的编码可逆，后一两位可能有“=”，生成的编码都是ascii字符。

因此对于python2来说，编解码相对要容易一些。python3因为要从Unicode转换一下，相对麻烦一些。一切见下例：

Python2

 1 def b64encode(s, altchars=None):
 2     """Encode a string using Base64.
 3 
 4     s is the string to encode.  Optional altchars must be a string of at least
 5     length 2 (additional characters are ignored) which specifies an
 6     alternative alphabet for the '+' and '/' characters.  This allows an
 7     application to e.g. generate url or filesystem safe Base64 strings.
 8 
 9     The encoded string is returned.
10     """
11     # Strip off the trailing newline
12     encoded = binascii.b2a_base64(s)[:-1]
13     if altchars is not None:
14         return encoded.translate(string.maketrans(b'+/', altchars[:2]))
15     return encoded

 1 def b64decode(s, altchars=None):
 2     """Decode a Base64 encoded string.
 3 
 4     s is the string to decode.  Optional altchars must be a string of at least
 5     length 2 (additional characters are ignored) which specifies the
 6     alternative alphabet used instead of the '+' and '/' characters.
 7 
 8     The decoded string is returned.  A TypeError is raised if s is
 9     incorrectly padded.  Characters that are neither in the normal base-64
10     alphabet nor the alternative alphabet are discarded prior to the padding
11     check.
12     """
13     if altchars is not None:
14         s = s.translate(string.maketrans(altchars[:2], '+/'))
15     try:
16         return binascii.a2b_base64(s)
17     except binascii.Error, msg:
18         # Transform this exception for consistency
19         raise TypeError(msg)

b64decode源码