Is there an onBackPressed() alternative for a service?

问题

I know that services cannot implement Back key press and I understand the rationale. But there is an app called SideBar (on Play Store) that reacts to back key presses. It is a service that adds a view as system overlay and removes the view when the back key is pressed. Can anybody explain how this is done?

Here is another app that does it well. I have scoured the web, but have not found a solution to this problem. Any ideas?

回答1:

It is probably done using system alert windows - so the service creates and manages a window that is added to the window manager, which has a custom callback set on it.

回答2:

here is nice example to addview in Service and also you can use listeners if you want in services.

i was also looking for the listeners implementation in service and finally found it.

remember to add permission

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>

and add your service class

<application>
.
 .
  <service android:name=".YourServiceClass"></service>
 .
.
</application>

in AndroidManifest.xml.

来源：https://stackoverflow.com/questions/18140052/is-there-an-onbackpressed-alternative-for-a-service