Python字符串的编码和解码

先举个例子：
#coding: gbk

unicodestring = u"Hello, 中国"

#Convent Unicode to plain Python string: "encode"
utf8string = unicodestring.encode("utf-8")
utf16string = unicodestring.encode("utf-16")
gbkstring = unicodestring.encode("gbk")
cp932string = unicodestring.encode("cp932")

#Convent plain Python string to Unicode: "decode"
unicodestring1 = unicode(utf8string, "utf-8")
unicodestring2 = unicode(utf16string, "utf-16")
unicodestring3 = unicode(gbkstring, "gbk")
unicodestring4 = unicode(cp932string, "cp932")

概括的说，调用一个unicode对象的encode方法，返回相应编码的string对象；调用某种编码的string对象的decode或调用unicode方法，返回一个unicode对象