public String getInputString(HttpServletRequest req) {
        String receivedString = "";

        try (BufferedReader reader = new BufferedReader(new InputStreamReader(req.getInputStream()))) {
            StringBuilder sb = new StringBuilder("");
            String tmp = null;

            while ((tmp = reader.readLine()) != null) {
                sb.append(tmp);
            }

            if (sb.length() > 0) {
                receivedString = sb.toString();
            }

        } catch (IOException e) {

        }

        return receivedString;
    }