Dictionary<string, string> sPara = GetRequestPost(ref parameterStr);

                string serializeString = JSONUtility.Serialize(sPara);

                serializeString = Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(serializeString));

System.Text.UTF8Encoding encoder = new System.Text.UTF8Encoding();

                        System.Text.Decoder utf8Decode = encoder.GetDecoder();

                        byte[] todecode_byte = Convert.FromBase64String(base64DataString);

                        int charCount = utf8Decode.GetCharCount(todecode_byte, , todecode_byte.Length);

                        char[] decoded_char = new char[charCount];

                        utf8Decode.GetChars(todecode_byte, , todecode_byte.Length, decoded_char, );

                        string decodeResult = new String(decoded_char);

                        Dictionary<string, string> sPara = JSONUtility.Deserialize<Dictionary<string, string>>(decodeResult);