實現通知消息代碼:

NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
Notification notification = new NotificationCompat.Builder(Context)
            .setContentText("通知内容")
            .setContentTitle("通知标题")
            .setSmallIcon(android.R.mipmap.ic_launcher_round)
          .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher_round))
            .setWhen(System.currentTimeMillis())
            .build();
manager.notify(1,notification);