How to send and receive JSON between Android and ASP.net mvc

Question

How to send and receive JSON data Android and ASP.Net MVC ? I have an Android Login application, which has a Login activity class and a JSONParser class. Using the JSONParser class, I am passing the url of the mvc location, "POST" parameter and my parameters username, password as json to MVC. I have an ASP.net mvc code that accepts the username and password, and if a match is found, it will return json data as "username" : "admin, "success" : 1.

The code for Login Activity class is:

protected String doInBackground(String... arg0) {
    // TODO Auto-generated method stub

    new Thread() {          
        // Running Thread.
        public void run() {
            List<NameValuePair> params = new ArrayList<NameValuePair>();
            params.add(new BasicNameValuePair("userid", username.getText().toString().trim()));
            params.add(new BasicNameValuePair("password", password.getText().toString().trim()));

            JSONObject json = jsonParser.makeHttpRequest("http://localhost:8012/Login/Login","GET", params);
            Log.d("Create Response", json.toString());
            try {
                    int success = json.getInt("success");
                    if (success == 1) {

                        Intent newregistrationIntent = new Intent(MainActivity.this,mydashActivity.class);
                        startActivityForResult(newregistrationIntent, 0);
                    } 
                    else 
                    {
                                i=1;
                                flag=1;
                    }
                } catch (JSONException e) {
                            e.printStackTrace();
                }
        }
    }.start();


    return null;




}

The code for JSONParser is :

    public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";

    // constructor
    public JSONParser() {

    }

    // function get json from url
    // by making HTTP POST or GET mehtod
    public JSONObject makeHttpRequest(String url, String method,
            List<NameValuePair> params) {

        // Making HTTP request
        try {

            // check for request method
            if(method == "POST"){
                // request method is POST
                // defaultHttpClient
                DefaultHttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(url);
                httpPost.setEntity(new UrlEncodedFormEntity(params));


                httpPost.setHeader("Content-type", "application/json");





                HttpResponse httpResponse = httpClient.execute(httpPost);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();

            }else if(method == "GET"){
                // request method is GET
                DefaultHttpClient httpClient = new DefaultHttpClient();
                String paramString = URLEncodedUtils.format(params, "utf-8");
                url += "?" + paramString;
                HttpGet httpGet = new HttpGet(url);

                HttpResponse httpResponse = httpClient.execute(httpGet);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();
            }           


        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        // try parse the string to a JSON object
        try {
            jObj = new JSONObject(json);
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }

        // return JSON String
        return jObj;

    }
}

My ASP.Net MVC code is :

    using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using MvcApplication1.Models;
using System.Web.Script.Serialization;

namespace MvcApplication1.Controllers
{
    public class LoginController : Controller
    {
        Dictionary<string, object> loginParam = new Dictionary<string, object>();
        //
        // GET: /Login/

        [HttpGet]
        public ActionResult Login()
        {
            return View();
        }
        [HttpPost]
        public ActionResult Login(Login cs)
        {
            return Json(new { username="admin", success = 1 });

        }

        [HttpGet]
        public ActionResult Profile()
        {
            return View();
        }
        [HttpPost]
        public ActionResult Profile(Login cs)
        {
            return View("");
        }


    }
}

I am not sure whether actually a connection is made from android to the mvc code. I am also not sure whether the MVC controller is hit at the Login () by the android code. How to make sure, the JSON data is send from Android, as well as the data is returned from MVC code ?

Note: I am not actually comparing the data in MVC code. I am just returning the data. This is my first MVC code.

Answer 1

 public static String POST( String username,String password){
    String url=Constants.url_registration;
    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("username", username);
        jsonObject.accumulate("password", password);


        // 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 content   
        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;
}

Answer 2

because of you used "Get" method :

JSONObject json = jsonParser.makeHttpRequest("http://localhost:8012/Login/Login","GET", params);

While the login method is [httpPost]

[HttpPost] public ActionResult Login(Login cs) { return Json(new { username="admin", success = 1 });

}