java restful receive json

have an android application that consumes restful web service type, made wi=
th java. From android I call @ Get and perfect. Now I want to make the syst=
em login. Send to a @ Post method and verify some fields and return a true =
to my application or the number of user-id.

android:Login activity to send json.

public class MainActivity extends Activity {
TextView tvIsConnected;
EditText etName,etPass,etTwitter;
Button btnPost;
Person person;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    // get reference to the views
    tvIsConnected = (TextView) findViewById(R.id.tvIsConnected);
    etName = (EditText) findViewById(R.id.etName);
    etPass = (EditText) findViewById(R.id.etPass);

    btnPost = (Button) findViewById(R.id.btnPost);

    // check if you are connected or not
    if(isConnected()){
        tvIsConnected.setBackgroundColor(0xFF00CC00);
        tvIsConnected.setText("You are conncted");
    }
    else{
        tvIsConnected.setText("You are NOT conncted");
    }
}
public static String POST(String url, Person person){
    InputStream inputStream = null;
    String result = "";
    try {
        // 1. create HttpClient
        HttpClient httpclient = new DefaultHttpClient();
        // 2. make POST request to the given URL
        HttpPost httpPost = new HttpPost(url);
        String json = "";
        // 3. build jsonObject
        JSONObject jsonObject = new JSONObject();
        jsonObject.accumulate("name", person.getName());
        jsonObject.accumulate("country", person.getPass());

        // 4. convert JSONObject to JSON to String
        json = jsonObject.toString();

        // ** Alternative way to convert Person object to JSON string usin =
Jackson Lib
        // ObjectMapper mapper = new ObjectMapper();
        // json = mapper.writeValueAsString(person);
        // 5. set json to StringEntity
        StringEntity se = new StringEntity(json);
        // 6. set httpPost Entity
        httpPost.setEntity(se);
        // 7. Set some headers to inform server about the type of the conte=
nt
        httpPost.setHeader("Accept", "application/json");
        httpPost.setHeader("Content-type", "application/json");
        // 8. Execute POST request to the given URL
        HttpResponse httpResponse = httpclient.execute(httpPost);
        // 9. receive response as inputStream
        inputStream = httpResponse.getEntity().getContent();
        // 10. convert inputstream to string
        if(inputStream != null)
            result = convertInputStreamToString(inputStream);
        else
            result = "Did not work!";
    } catch (Exception e) {
        Log.d("InputStream", e.getLocalizedMessage());
    }
    // 11. return result
    return result;
}
    public void onClickbtn(View view) {
        switch(view.getId()){
            case R.id.btnPost:
                if(!validate())
                    Toast.makeText(getBaseContext(), "Enter some data!", To=
ast.LENGTH_LONG).show();
                // call AsynTask to perform network operation on separate t=
hread
                new HttpAsyncTask().execute("http://hmkcode.appspot.com/jso=
nservlet");
            break;
        }
    }
public boolean isConnected(){
    ConnectivityManager connMgr = (ConnectivityManager) getSystemService(=
Activity.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
        if (networkInfo != null && networkInfo.isConnected())
            return true;
        else
            return false;
}
private class HttpAsyncTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... urls) {

        person = new Person();
        person.setName(etName.getText().toString());
        person.setPass(etPass.getText().toString());

        return POST(urls[0],person);
    }
    // onPostExecute displays the results of the AsyncTask.
    @Override
    protected void onPostExecute(String result) {
        Toast.makeText(getBaseContext(), "Data Sent!", Toast.LENGTH_LONG).s=
how();
   }
}
private boolean validate(){
    if(etName.getText().toString().trim().equals(""))
        return false;
    else if(etPass.getText().toString().trim().equals(""))
        return false;

    else
        return true;
}
private static String convertInputStreamToString(InputStream inputStream) t=
hrows IOException{
    BufferedReader bufferedReader = new BufferedReader( new InputStreamRe=
ader(inputStream));
    String line = "";
    String result = "";
    while((line = bufferedReader.readLine()) != null)
        result += line;
    inputStream.close();
    return result;
}
With this method, or query, I test my webservice manually. Now I would like=
 to do it in @ Post and the pass and usuario (user) parameters which will b=
e shipped out in my android json.

@GET
    @Path("/consulll")
    @Produces({"application/json"})

public List <Padres> returnTitle4(){

   String jpql = "SELECT p FROM Padres p";
Query query = em.createQuery(jpql);
 //query.setParameter("pass", "1234");
 //query.setParameter("usuario", "William");
 List<Padres> resultados = query.getResultList();
    return resultados;
}
Thank you very much and sorry if you do not understand something for my bad=
 English level.