无法在服务器上发布数据

Question

我在服务器上发布值并获得响应。但问题是它显示我为null作为响应。我正在做的错误。我尝试了很多方法但仍然没有找到任何解决方案。任何人都可以帮助我。 以下是我的代码 -

class SendPostReqAsyncTask extends AsyncTask<String, Void, String> {
        String OTPTxt = otp.getText().toString();

        int CustID = 2;

        @Override
        protected String doInBackground(String... params) {

            HttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost("mylink?CustID=" + CustID + "&OTP=" + OTPTxt);
            List<NameValuePair> nameValuePairList = new ArrayList<NameValuePair>();
            try {
                UrlEncodedFormEntity urlEncodedFormEntity = new UrlEncodedFormEntity(nameValuePairList);
                httpPost.setEntity(urlEncodedFormEntity);
                HttpResponse httpResponse = httpClient.execute(httpPost);
                InputStream inputStream = httpResponse.getEntity().getContent();

                InputStreamReader inputStreamReader = new InputStreamReader(inputStream);

                BufferedReader bufferedReader = new BufferedReader(inputStreamReader);

                StringBuilder stringBuilder = new StringBuilder();

                String bufferedStrChunk = null;

                while ((bufferedStrChunk = bufferedReader.readLine()) != null) {
                    stringBuilder.append(bufferedStrChunk);
                }

                return stringBuilder.toString();

            } catch (ClientProtocolException cpe) {
                System.out.println("Firstption caz of HttpResponese :" + cpe);
                cpe.printStackTrace();
            } catch (IOException ioe) {
                System.out.println("Secondption caz of HttpResponse :" + ioe);
                ioe.printStackTrace();
            }

            return null;
        }


       @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(OTPScreen1.this, "Posting Data to server", Toast.LENGTH_SHORT).show();
                    Toast.makeText(OTPScreen1.this, "posting data " + responseServer, Toast.LENGTH_SHORT).show();
                }
            });
        }
    }

在buttonclick上调用了这个方法

button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                 new SendPostReqAsyncTask().execute();
}
});