python unicode string

现象，字典的key类型是str。
用unicode类型查询返回空。
用str强制转换一下就可以了

Unicode字符串可以用多种方式编码为普通字符串, 依照你所选择的编码(encoding):

 1 #将Unicode转换成普通的Python字符串:"编码(encode)"  2 unicodestring = u"Hello world"  3 utf8string = unicodestring.encode("utf-8")  4 asciistring = unicodestring.encode("ascii")  5 isostring = unicodestring.encode("ISO-8859-1")  6 utf16string = unicodestring.encode("utf-16")  7   8   9 #将普通的Python字符串转换成Unicode: "解码(decode)"  10 plainstring1 = unicode(utf8string, "utf-8")  11 plainstring2 = unicode(asciistring, "ascii")  12 plainstring3 = unicode(isostring, "ISO-8859-1")  13 plainstring4 = unicode(utf16string, "utf-16")  14   15 assert plainstring1==plainstring2==plainstring3==plainstring4