I mean if I want to get access to all notification coming in notification drawer. Just wondering how pushbullet and other wearable accessories does that ? Reading all your notifications and pushing them to web servers / particular devices.
You can use NotificationListenerService, which requires permission BIND_NOTIFICATION_LISTENER_SERVICE.
Here is Link https://developer.android.com/reference/android/service/notification/NotificationListenerService.html
and sample code for reference https://github.com/pgajbhiye/NotificationsSample