the byte buffer that encoding with GBK, GB18030, GB2132, ISO8859_1 .etc
the encoding method: GBK, GB18030, GB2132, ISO8859_1
Encode a utf8 string to a buffer that encoding with GBK, GB18030, GB2132, ISO8859_1 .etc
the utf8 string
the encoding method: GBK, GB18030, GB2132, ISO8859_1
Decode the byte buffer that encoding with GBK, GB18030, GB2132, ISO8859_1 .etc to a utf-8 string.