AsyncTask with Gson Libarary For Json Parsing


Android AsyncTask with Gson Libarary For Json Parsing

Gson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. Gson can work with arbitrary Java objects including pre-existing objects that you do not have source-code of.
There are a few open-source projects that can convert Java objects to JSON. However, most of them require that you place Java annotations in your classes; something that you can not do if you do not have access to the source-code. Most also do not fully support the use of Java Generics. Gson considers both of these as very important design goals.

Gson Goals

Provide simple toJson() and fromJson() methods to convert Java objects to JSON and vice-versa
Allow pre-existing unmodifiable objects to be converted to and from JSON
Extensive support of Java Generics
Allow custom representations for objects
Support arbitrarily complex objects (with deep inheritance hierarchies and extensive use of generic types)
Here I create a empty class name as DataModel and implement it as a Serializable


import java.io.Serializable;

public class DataModel implements Serializable{

}



This is a empty class so you can add any object to this class and get the value of that objects

Now we write one interface which will give the return datamodel
 
public interface NotifyTasKDone {

    public void onTaskDone(DataModel in);

}


So start writting an AsyncTask. Create a class name as TaskHandler or any other name you may want.

Here we are parsing the URL via the post methods. We get the response as a encrepted format or normal


@SuppressWarnings("deprecation")

public class TaskAsycnHandler extends AsyncTask<String, Void, DataModel> {

public NotifyTasKDone taskDone;

private Activity activity;

private ProgressDialog progressDialog;

private int msgId;

private int val;

private Map<String, String> keyValue;

@SuppressWarnings("deprecation")

private HttpClient httpclient;

@SuppressWarnings("deprecation")

private HttpPost httppost;

@SuppressWarnings("deprecation")

private List<NameValuePair> nameValuePairs;

AnimationDrawable rocketAnimation;

JsonElement jsonResponse = null;

private String action;

private static final String TAG = "MyURLs";

public TaskAsycnHandler(NotifyTasKDone taskDone, Activity activity,

int msgId, int val, Map<String, String> keyValue) {

        this.taskDone = taskDone;

        this.activity = activity;

             this.msgId = msgId;

              this.val = val;

             this.keyValue = keyValue;


             this.action = keyValue.get("action");

      }

@SuppressLint("NewApi")

@Override

protected void onCancelled(DataModel result) {

// TODO Auto-generated method stub

         super.onCancelled(result);

    }

@Override

protected synchronized void onPostExecute(DataModel result) {

           taskDone.onTaskDone(result);

       Log.v("webservice", final_result);

          if (val == 2){

          Constants.flagRoomList_Search = false;

          System.err.println("*-*-*545644646 *-*-*");

       } else {

                progressDialog.dismiss();

         }

     }

@SuppressLint("NewApi")

@Override

protected void onPreExecute() {

           if (val == 0) {

               progressDialog = ProgressDialog.show(activity, "", "");

               progressDialog.setContentView(R.layout.progress_circular);



         WindowManager.LayoutParams params =         progressDialog.getWindow().getAttributes();

        params.y =200;

             progressDialog.getWindow().setAttributes(params);


} else if (val == 1) {

         progressDialog = ProgressDialog.show(activity, activity

        .getResources().getString(R.string.str_Wait), activity

        .getResources().getString(R.string.str_Progressing));

         progressDialog.setContentView(R.layout.progress);

         progressDialog.setCancelable(false);

     ImageView progress = (ImageView) progressDialog

       .findViewById(R.id.progressbar);

 

     rocketAnimation = (AnimationDrawable) progress.getBackground();

        rocketAnimation.start();

     TextView hold_msg = (TextView) progressDialog

     .findViewById(R.id.hold_msg);

     hold_msg.setText(msgId);

  }else if (val == 2)

     Constants.progress_flag = true;

     else

     Constants.progress_flag = false;


}

  String result = "",final_result="";

@SuppressWarnings("deprecation")

protected synchronized DataModel doInBackground(String... params) {

// TODO Auto-generated method stub

      final HttpParams httpParams = new BasicHttpParams();

      HttpConnectionParams.setSoTimeout(httpParams, 340000);

      SchemeRegistry registry = new SchemeRegistry();

    registry.register(new Scheme("http", new PlainSocketFactory(), 80));

    registry.register(new Scheme("https",

      new TlsSniSocketFactory(), 443));

      HttpParams httpparams = new BasicHttpParams();

      HttpConnectionParams.setConnectionTimeout(httpparams, 120000);

      HttpConnectionParams.setSoTimeout(httpparams, 120000);

      httpclient = new DefaultHttpClient(new ThreadSafeClientConnManager(

    httpparams, registry), httpparams);


  

      httppost = new HttpPost(Constants.URL);

   

     nameValuePairs = new ArrayList<NameValuePair>(keyValue.size());

        for (Entry<String, String> entry : keyValue.entrySet()) {

          String keys = entry.getKey();

          String values = entry.getValue();

                nameValuePairs.add(new BasicNameValuePair(keys, values));

       }


    try {
       httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs, "UTF-8"));

       {

         String urldata = nameValuePairs.toString().replace(", ", "&");

         System.out.println("Urls ===> " + Constants.URL + ""

           + urldata.substring(1, urldata.length() - 1)

           + "&debug=1");

          Log.v("webservice", Constants.URL + ""

          + urldata.substring(1, urldata.length() - 1)

          + "&debug=1");

      }

       InputStream instream;

            HttpResponse response = httpclient.execute(httppost);

       HttpEntity entity = response.getEntity();

      if (entity != null) {

          if (Constants.isGZIPPED) {

           instream = entity.getContent();

           result = Constants.uncompressInputStream(instream);

           } else {

             instream = entity.getContent();

             result += Constants.convertStreamToString(instream);

           }

          System.out.println("** result **" + result);

        }

} catch (Exception e) {

      Constants.TimeOutError = "No Responce";

      System.err.println("noReponce time out error :==> "+e.getMessage());

      e.printStackTrace();

   }

       final_result += result;

       String st = result;

       DataModel model = null;

       InputStream is = new ByteArrayInputStream(st.getBytes());



       Class<DataModel> cls = null;

       String cls_name = params[0].toString();

       System.out.println("cls_name" + cls_name);

       JsonReader reader = new JsonReader(new InputStreamReader(is));

       JsonParser parser = new JsonParser();

       jsonResponse = parser.parse(reader);

// parse the response

// YourResponseClass response;

try {

    cls = (Class<DataModel>) Class.forName(cls_name);

    } catch (ClassNotFoundException e) {

       // TODO Auto-generated catch block

       e.printStackTrace();

   }

    Gson gson = new Gson();

     // Gson gson = new GsonBuilder().serializeNulls().create();

try {

         model = gson.fromJson(jsonResponse, cls);

    } catch (RuntimeException r) {

        Constants.TimeOutError = "Data is not in Json Format";

        System.err.println("Data is not in Json Format");

      }

        return model;

     }

}




Make a class called as Constants.java which will hold the constant variables and function  this variable and function can call directly. Here Constants.isGZIPPED is a boolean variable
  If the json data from web is gzip ie compress then this variable become true and I call a function which will unzip the json response and fill our data model with
respected data
    uncompressInputStream is a function which will un compress the data and the convertStreamToString function is for normal json response

        Now see the below Constants.java file class
public class Constants {

public static boolean isGZIPPED = true;

public static boolean progress_flag = false;

public static String TimeOutError;

public static String uncompressInputStream(InputStream inputStream)

throws IOException {

                 StringBuilder value = new StringBuilder();

                 GZIPInputStream gzipIn = null;

                 InputStreamReader inputReader = null;

                  BufferedReader reader = null;

        try {

            gzipIn = new GZIPInputStream(inputStream);

            inputReader = new InputStreamReader(gzipIn, "UTF-8");

            reader = new BufferedReader(inputReader);

            String line = "";

         while ((line = reader.readLine()) != null) {

                 value.append(line + "\n");

            }

         } finally {

       try {

               if (gzipIn != null) {

                       gzipIn.close();

             }

             if (inputReader != null) {

                      inputReader.close();

            }

          if (reader != null) {

                 reader.close();

            }

        } catch (IOException io) {

                    io.printStackTrace();

            }

           }

          return value.toString();

}

public static String convertStreamToString(InputStream is) {

       BufferedReader reader = new BufferedReader(new InputStreamReader(is));

           StringBuilder sb = new StringBuilder();

              String line = null;

               try {

                   while ((line = reader.readLine()) != null) {

                          sb.append(line + "\n");

              }

             } catch (IOException e) {

                          e.printStackTrace();

            } finally {

           try {

                     is.close();

              } catch (IOException e) {

                      e.printStackTrace();

             }

        }

           return sb.toString();

       }

}




Lets start to create a sample app, create a android project name as xyz....

Here I create a LoginActivity.java, It have edittext box for user name and password & login button

See the below code for this one

public class LoginActivity extends Activity implements OnClickListener,

NotifyTasKDone {

private Context currObj;

private EditText user_name, password;

private Login_model login_model;

private Map<String, String> keypair;

@Override

protected void onCreate(Bundle savedInstanceState) {

   super.onCreate(savedInstanceState);

   setContentView(R.layout.login_activity);

   initialized();

}

private void initialized() {

    user_name = (EditText) findViewById(R.id.user_name);

    password = (EditText) findViewById(R.id.password);

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

     btn_sign.setOnClickListener(this);


}

@Override

public void onClick(View v) {

// TODO Auto-generated method stub

            switch (v.getId()) {

            case R.id.btn_sign:

                     if (user_name.getText().length() <= 0) {

                   //Show Error Message

             } else if (Constants.isValidEmailAddress(user_name.getText()

                 .toString()) == false) {

                      //Show Error Message

             } else if (password.getText().length() <= 0) {

                      //Show Error Message

             } else {

               LoginWebService(user_name.getText().toString(), password

                   .getText().toString());

             }

            break;

         default:

        break;

       }

   }

@SuppressWarnings("unchecked")

private void LoginWebService(String username, String password) {

// TODO Auto-generated method stub

        Constants.isGZIPPED = true;

        try {

         this.username = username;

          if (NetworkUtil.isNetworkAvailable(currObj)) {


           keypair = new HashMap<String, String>();

           keypair.put("action", "customer_login");


           keypair.put("device_type", "android");

           keypair.put("customer_email", username);


           keypair.put("customer_password", password);

          final String model_name = "com.SampleApp.models.Login_model";

          final TaskAsycnHandler tt = new TaskAsycnHandler(this,

              getActivity(), R.string.loginmsg, 1, keypair);

              tt.execute(model_name);

        } else {

            NetworkUtil.noNetworkAlert(currObj, this.getResources()

             .getString(R.string.noInternet));

         }

     } catch (Exception e) {

    }

}



@Override

public void onTaskDone(DataModel in) {

       login_model = (Login_model) in;

            if (login_model != null) {

          String login_msg = login_model.getlogin_msg();

         if (login_msg.toLowerCase().equals("true")) {

                System.out.println("Login Success");

          }else {

           System.out.println("Login Fail");

    }

   }

}
Now here we write a model class,its a class just with a 

getter methods


Gson libary having some structure for writting getter 

method


Following class show the Login_model

import java.io.Serializable;

import com.google.gson.annotations.SerializedName;



public class Login_model extends DataModel {

   private static final long serialVersionUID = 1L;

     @SerializedName("login")

      public String login_msg;



      public String getlogin_msg() {

       return login_msg;

      }

 }

Here @SerializedName("login") is a json key which we get 

from the web services





Thanks

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