unable to interpret message from GCM

Question

I'm trying to understand how GCM works. To do so, I copy/paste the code that http://developer.android.com/ proposes in the section "implementing a GCM client".

I don't have a server for now, so it's just a http request that I send from eclipse.

Here is the request:

HttpEntity entity = new ByteArrayEntity(contenu.getBytes("UTF-8"));
    HttpClient client = new DefaultHttpClient();
    HttpPost post = new HttpPost(this.getAdresse());
    post.addHeader("Authorization", "key=AIzaSyANnvuPYJaSIDM7gorqdKh25uvpNA-4rvk");
    post.addHeader("Content-Type", "application/json");
    post.setEntity(entity);

    HttpResponse response = client.execute(post);

where "contenu" is this String:

{ "data": {
"message":"hello"
  },
  "registration_ids": ["4", "8", "15", "16", "23", "42"]
}

On my client app, I have this IntentService (found on the developers site):

package com.test.testnotification3;

 import com.google.android.gms.gcm.GoogleCloudMessaging;
import com.test.testnotification3.R;

import core.GcmBroadcastReceiver;
import android.app.IntentService;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.SystemClock;
import android.support.v4.app.NotificationCompat;
import android.util.Log;

public class GcmIntentService extends IntentService {
public static final int NOTIFICATION_ID = 1;
private NotificationManager mNotificationManager;
NotificationCompat.Builder builder;
static final String TAG = "GCMDemo";

public GcmIntentService() {
    super("GcmIntentService");
}

@Override
protected void onHandleIntent(Intent intent) {
    Bundle extras = intent.getExtras();
    GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this);

    // The getMessageType() intent parameter must be the intent you received
    // in your BroadcastReceiver.
    String messageType = gcm.getMessageType(intent);



    if (!extras.isEmpty()) {  // has effect of unparcelling Bundle
        /*
         * Filter messages based on message type. Since it is likely that GCM
         * will be extended in the future with new message types, just ignore
         * any message types you're not interested in, or that you don't
         * recognize.
         */
        if (GoogleCloudMessaging.
                MESSAGE_TYPE_SEND_ERROR.equals(messageType)) {
            sendNotification("Send error: " + extras.toString());
        } else if (GoogleCloudMessaging.
                MESSAGE_TYPE_DELETED.equals(messageType)) {
            sendNotification("Deleted messages on server: " +
                    extras.toString());
            // If it's a regular GCM message, do some work.
        } else if (GoogleCloudMessaging.
                MESSAGE_TYPE_MESSAGE.equals(messageType)) {



            Log.i(TAG, "Completed work @ " + SystemClock.elapsedRealtime());
            // Post notification of received message.
            sendNotification("Received: " + extras.toString());
            Log.i(TAG, "Received: " + extras.toString());
        }
    }
    // Release the wake lock provided by the WakefulBroadcastReceiver.
    GcmBroadcastReceiver.completeWakefulIntent(intent);
}

// Put the message into a notification and post it.
// This is just one simple example of what you might choose to do with
// a GCM message.
public void sendNotification(String msg) {
    mNotificationManager = (NotificationManager)
            this.getSystemService(Context.NOTIFICATION_SERVICE);

    PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
            new Intent(this, MainActivity.class), 0);
    long[] pattern = {0,1000};

    NotificationCompat.Builder mBuilder =
            new NotificationCompat.Builder(this)
    .setSmallIcon(R.drawable.ic_launcher)
    .setContentTitle("Coucou Matthieu")
    .setStyle(new NotificationCompat.BigTextStyle()
    .bigText(msg))
    .setContentText(msg)
    .setVibrate(pattern);

    mBuilder.setContentIntent(contentIntent);
    mNotificationManager.notify(NOTIFICATION_ID, mBuilder.build());
    }
}

And I got this message in my Logcat:

07-06 19:26:15.627: I/GCMDemo(5095): Received: Bundle[{msg=hello,     android.support.content.wakelockid=1, collapse_key=do_not_collapse, from=472226063168}]

So my question is: how can I get just the "msg" field ?

Thank you for your answer(s)!

Answer 1

You can get the data from the Bundle associated with the Intent. In this case since it's a string you can call getString() passing the proper key ("msg"):

Bundle extras = intent.getExtras();
String msg = extras.getString("msg");

You can do this in the branch where you know that the GCM message is of message type:

Bundle extras = intent.getExtras();

...

} else if (GoogleCloudMessaging.MESSAGE_TYPE_MESSAGE.equals(messageType)) {
  String msg = extras.getString("msg");
  // Do something with msg
}