func GbkToUtf8(s []byte) ([]byte,error) {
    reader := transform.NewReader(bytes.NewReader(s),simplifiedchinese.GBK.NewDecoder())
    d,e := IoUtil.ReadAll(reader)
    if e != nil {
        return nil,e
    }
    return d,nil
}

func Utf8ToGbk(s []byte) ([]byte,simplifiedchinese.GBK.NewEncoder())
    d,nil
}