Simple GCM Implementation

AndroidManifest.xml

    <!-- GCM permissions -->
    <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
    <uses-permission android:name="android.permission.GET_ACCOUNTS" />
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
    <uses-permission android:name="android.permission.VIBRATE" />

    <permission
        android:name="com.example.android.app.gcm.permission.C2D_MESSAGE"
        android:protectionLevel="signature" />
    <uses-permission android:name="com.example.android.app.gcm.permission.C2D_MESSAGE" />
    <!-- GCM permissions -->
    
    <!-- Inside Application TAG GCM -->
        <receiver
            android:name=".gcm.GCMReceiver"
            android:permission="com.google.android.c2dm.permission.SEND">
            <intent-filter>
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
                <category android:name="com.example.android.app" />
            </intent-filter>
        </receiver>
        <service android:name=".gcm.GCMService" />

        <meta-data
            android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />
        <!-- GCM -->

build_properties.xml

    <!-- GCM -->
    <string name="gcm_project_number">123456789098</string>

GCMReceiver.java

public class GCMReceiver extends WakefulBroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        ComponentName comp = new ComponentName(context.getPackageName(),GCMService.class.getName());
        startWakefulService(context, (intent.setComponent(comp)));
        setResultCode(Activity.RESULT_OK);
    }
}

GCMService.java

public class GCMService extends IntentService implements SaveAudioMessageTask.SaveAudioMessageListener {

    private static final String TAG = GCMService.class.getSimpleName();
    public static final String KEY_EXTRAS_ACTION_RECEIVED_AUDIO_MESSAGE = "audioMessage";
    private AudioMessage receivedAudioMessage;
    private ActionType action;

    private enum ActionType { NEW_AUDIO_MESSAGE }

    @DebugLog
    public GCMService() {
        super("FoundationGCMService");
    }

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

        if (!extras.isEmpty()) {

            Gson jsonParser = FoundationAPIBuilder.buildJsonParser();

            if (extras.containsKey(KEY_EXTRAS_ACTION_RECEIVED_AUDIO_MESSAGE)) {
                action = ActionType.NEW_AUDIO_MESSAGE;
                Log.i(TAG, "Received push, RECEIVED_AUDIO_MESSAGE");
                this.receivedAudioMessage = jsonParser.fromJson(extras.getString(KEY_EXTRAS_ACTION_RECEIVED_AUDIO_MESSAGE), AudioMessage.class);
                Log.v(TAG, extras.getString(KEY_EXTRAS_ACTION_RECEIVED_AUDIO_MESSAGE));

                new SaveAudioMessageTask(this, true, true, -1).execute(this.receivedAudioMessage);
            }
        }

        GCMReceiver.completeWakefulIntent(intent);
    }

    @DebugLog
    @Override
    public void onPostExecute() {
        Intent resultIntent = new Intent(this, MainActivity.class);

        switch (action) {
            case NEW_AUDIO_MESSAGE:
                resultIntent.putExtra(MainActivity.KEY_EXTRAS_START_ON_MESSAGES, true);
                TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
                stackBuilder.addParentStack(MainActivity.class);
                stackBuilder.addNextIntent(resultIntent);
                PendingIntent resultPendingIntent =
                        stackBuilder.getPendingIntent(
                                0,
                                PendingIntent.FLAG_UPDATE_CURRENT
                        );

                Uri soundUri = Uri.parse("android.resource://" + this.getPackageName() + "/" + R.raw.notification);
                String notificationBody = this.receivedAudioMessage.getFrom().getFullname() + " " + this.getResources().getString(R.string.notification_new_message_text);
                NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this)
                        .setSmallIcon(R.drawable.ic_launcher)
                        .setContentTitle(this.getResources().getString(R.string.notification_new_message_title))
                        .setOngoing(false)
                        .setContentIntent(resultPendingIntent)
                        .setAutoCancel(true)
                        .setContentText(notificationBody)
                        .setTicker(notificationBody)
                        .setDefaults(Notification.DEFAULT_VIBRATE | Notification.DEFAULT_LIGHTS);
                if (SharedPreferencesHelper.getBoolean(SharedPreferencesHelper.KEY_PREFS_PLAY_NOTIFICATION_SOUNDS, true)) {
                    mBuilder
                            .setSound(soundUri);
                }
                NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
                mNotificationManager.notify(R.id.notification_id, mBuilder.build());
                break;
        }

    }
}

GCMTools.java

public class GCMTools {
    private final static int PLAY_SERVICES_RESOLUTION_REQUEST = 9000;

    public static boolean isGooglePlayAvailable(Activity act) {
        int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(act);
        if (resultCode != ConnectionResult.SUCCESS) {
            if (GooglePlayServicesUtil.isUserRecoverableError(resultCode)) {
                GooglePlayServicesUtil.getErrorDialog(resultCode, act, PLAY_SERVICES_RESOLUTION_REQUEST).show();
            }
            return false;
        }
        return true;
    }

    public static void registerToGCM(Activity act){
        if (isGooglePlayAvailable(act)) {

            UserLocalStorageHandler userDB = new UserLocalStorageHandler(act);

            User currentUser = null;
            try {
                currentUser = userDB.getCurrentUser();
            } catch (SQLException e) {
                e.printStackTrace();
            }

            if (currentUser == null || currentUser.getGCMRegistrationId() == null || currentUser.getGCMRegistrationId().trim().isEmpty()) {
                GCMRegistration regTask = new GCMRegistration(act, userDB);
                regTask.execute();
            }
        }
    }

    private static class GCMRegistration extends AsyncTask{
        private final Context context;
        private final UserLocalStorageHandler usersDB;

        public GCMRegistration(Context ctx, UserLocalStorageHandler usersDB){
            super();
            this.context = ctx;
            this.usersDB = usersDB;
        }

        @Override
        protected Object doInBackground(Object[] params) {
            try{
                GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this.context);
                String registrationID = gcm.register(this.context.getString(R.string.gcm_project_number));
                Log.d("GCM", "Registered with regID: " + registrationID);
                User gcmUpdateData = new User();
                User currentUser = this.usersDB.getCurrentUser();
                gcmUpdateData.setRemoteid(currentUser.getRemoteid());
                gcmUpdateData.setGCMRegistrationId(registrationID);
                QuikeyAPIBuilder.getApiInstance().userPut(gcmUpdateData);
                currentUser.setGCMRegistrationId(registrationID);
                this.usersDB.saveCurrentUser(currentUser);
            } catch (IOException e) {
                e.printStackTrace();
            } catch (SQLException e) {
                e.printStackTrace();
            } catch (RetrofitError e){
                e.printStackTrace();
            }

            return null;
        }
    }
}

MainActivity.java

// ...

    @Override
    protected void onResume() {
        super.onResume();
        // ...
        GCMTools.registerToGCM(this);
        // ...
    }
    
// ...