สอบถามผู้รู้ครับเรื่อง Android ผมได้เรียก Web Api เรียบร้อยแล้วแต่มันจะต้อง Response Json กลับมา

protected Void doInBackground(String... urls)   {
            try
            {
                URL url = new URL(urls[0]);
                HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                conn.setReadTimeout(10000);
                conn.setConnectTimeout(15000);
                conn.setRequestMethod("POST");
                conn.setDoInput(true);
                conn.setDoOutput(true);
                conn.setRequestProperty("Content-Type", "application/json;");
                conn.setRequestProperty("Accept", "application/json");
                conn.setRequestProperty("Access-Control-Allow-Origin", "*");

                String json = "{\"Domain\": \"google.th\", \"Username\": \"thanapon.p\", \"Password\": \"XXXXX\"}";

                OutputStream os = conn.getOutputStream();
                os.write(json.getBytes("UTF-8"));
                os.close();
            }
            catch(Exception ex)
            {
                Log.d("THAPO", ex.toString());
            }

            return null;
        }