utf8转换为gb2312报错， 原因：gb2312对一些很生僻的中文字并不支持，比如 “囧” “苶”

gistfile1.py

Python 2.7.2 |EPD 7.2-2 (32-bit)| (default, Sep 14 2011, 11:02:05) [MSC v.1500 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> err = u'\u6c39'
>>> print err
氹
>>> err.encode("gb2312")

Traceback (most recent call last):
  File "<pyshell#2>", line 1, in <module>
    err.encode("gb2312")
UnicodeEncodeError: 'gb2312' codec can't encode character u'\u6c39' in position 0: illegal multibyte sequence
>>> err.encode("GBK")
'\x9a\xeb'
>>> err.encode("GB18030")
'\x9a\xeb'
>>> 

Python 2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
==== No Subprocess ====

print u'\u2764'
❤
u'\u2764'.encode('gb2312')
Traceback (most recent call last):
File "<pyshell#1>", line 1, in
u'\u2764'.encode('gb2312')
UnicodeEncodeError: 'gb2312' codec can't encode character u'\u2764' in position 0: illegal multibyte sequence