具有多个侦听器的android服务

Question

I am having some trouble creating a NON-IPC service that allows adding/removing multiple listeners at various times, for example, I would like to be able to contact the service and "subscribe" to its events any time, or "unsubscribe" from it. The service wakes up every once in a while and sends an event to all subscribed listeners.

I have been looking at stackoverflow examples, googling, etc, particularly I found something similar here: android restful api

In that example, the suggestion is to use ResultReceiver to serve as a callback from a service. But in this approach, doesn't it mean that the service can only notify listeners sent to it as part of the first intent (ie I cannot add/remove listeners whenever I want)?

Also, in that example, what happens if the activity gets destroyed by the OS for some reason, but the service still has a reference to the listener and tries to invoke it? The listener will try to perform some action on the activity, which no longer exists, right?

Maybe I am missing something... I'd appreciate some input if possible..

Tnx

Answer 1

First, 'sleeping' services are anti-pattern in Android. If you need to do something periodically, start your service using AlarmManager. Second, the service can be restarted at any time, so you cannot rely on 'subscribing' where you keep references to other components (activities mostly). If you need to send a notification to multiple activities, use a broadcast receiver. Activities can register for it statically (using AndroidManifest.xml), or dynamically (with code).