FirebaseMessagingService.java

public class FirebaseMessagingService extends com.google.firebase.messaging.FirebaseMessagingService {

    private NotificationManager notificationManager;
    private int NOTIFICATION_ID;
    public static final String ANDROID_CHANNEL_ID = "com.kyawhtut.firebaseandwebtesting.ANDROID";

    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        String message = remoteMessage.getData().get("message");
        String imageUri = remoteMessage.getData().get("image");
        showNotification(message, imageUri);
    }

    private void showNotification(String message, String image) {
        Log.i("Message", message);
        Intent intent = new Intent(this, MainActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0 /* Request code */, intent,
                PendingIntent.FLAG_ONE_SHOT);

        Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, ANDROID_CHANNEL_ID)
                .setLargeIcon(BitmapFactory.decodeResource(this.getResources(), R.drawable.place_holder))/*Notification icon image*/
                .setSmallIcon(R.mipmap.ic_launcher)
                .setContentTitle(message)
                .setStyle(new NotificationCompat.BigPictureStyle()
                        .bigPicture(BitmapFactory.decodeResource(this.getResources(), R.drawable.place_holder)))/*Notification with Image*/
                .setAutoCancel(true)
                .setSound(defaultSoundUri)
                .setContentIntent(pendingIntent);

        notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
            createNotificationChannel(notificationManager);
        }
        NOTIFICATION_ID = (int) Math.random();
        notificationManager.notify(NOTIFICATION_ID, notificationBuilder.build());
        fetchBitmapFromURLAsync(image, notificationBuilder);
    }

    @RequiresApi(api = Build.VERSION_CODES.O)
    private void createNotificationChannel(NotificationManager mNotificationManager) {
        if (mNotificationManager.getNotificationChannel(ANDROID_CHANNEL_ID) == null) {
            NotificationChannel notificationChannel =
                    new NotificationChannel(ANDROID_CHANNEL_ID,
                            this.getString(R.string.app_name),
                            NotificationManager.IMPORTANCE_LOW);

            notificationChannel.setDescription(
                    this.getString(R.string.app_name));

            mNotificationManager.createNotificationChannel(notificationChannel);
        }
    }

    private void fetchBitmapFromURLAsync(final String imageUrl, final NotificationCompat.Builder builder) {
        Log.i("Fetch Image : ", imageUrl);
        GlideApp.with(this)
                .asBitmap()
                .load(imageUrl)
                .into(new SimpleTarget<Bitmap>() {
                    @Override
                    public void onResourceReady(@NonNull Bitmap resource, @Nullable Transition<? super Bitmap> transition) {
                        Log.i("Resource Ready","true");
                    }
                });
    }
}