检测最近删除的小部件

Question

I created a widget which uses a background service for update notifications.

I want to stop the background service if the last widget is removed from the home screen(s).

How can I detect number of widgets remaining in home screen?

Answer 1

Ok, I figured out a way that doesn't involve having to store any persistent information. However even this looks like a hack to me. Inserted the following in the onReceive -

@Override
public void onReceive(Context context, Intent intent) {
        if (AppWidgetManager.ACTION_APPWIDGET_DELETED.equals(sIntentAction)) {
            AppWidgetManager amgr = AppWidgetManager.getInstance(context);
            int length = amgr.getAppWidgetIds(intent.getComponent()).length;
            if (length==0) WidgetService.StopService(context);
        }
        super.onReceive(context, intent);
}

It works, and is the best solution I could find, but I am not very happy with it.

I needed to do this in onReceive and not onDeleted , since the intent object is required to do intent.getComponent() . I don't like the fact because the documentation claims that one will rarely need to touch the onReceive , and need to count remaining widgets seems to be a reasonable expectation in onDeleted . However unfortunately it provides count of widgets being deleted, and not count remaining. Is there any way to do this in the onDeleted instead?

(Slowly I seem to get the feeling that a lot of Android coding is actually hacking - and the code to get a job done mostly uses undocumented or unexpected avenues.)

Answer 2

If you created a AppWidgetProvider for your Widget , it should have an onUpdate() method. One of the arguments for onUpdate() is the int[] ids . This is actually an array of all of the AppWidget instances receiving onUpdate() requests. If the size of ids is 1, then the next delete is your last widget. :)

Hope this helps, FuzzicalLogic

Answer 3

I had a similar issue with my application and this is what I ended up doing to figure out if I had deleted the last widget or not, which allowed me to stop my service and update a preference item that was saved.

@Override
public void onDisabled(Context context)
{
    // When this get called I need to figure out how to set the preference 
    // homeWidgetSetup = false.
    AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
    ComponentName thisAppWidget = new ComponentName(context, BasicHomeWidget.class.getName());
    int[] appWidgetIds = appWidgetManager.getAppWidgetIds(thisAppWidget);

    if(appWidgetIds.length < 1)
    {
        Log.d(TAG, "Removed the last widget!");
        Intent intent = new Intent(context, KMMDService.class);
        intent.putExtra("lastWidgetDeleted", true);
        context.startService(intent);
    }
}

Then I just tested looked at the extra passed to my service on onStartCommand and if has "lastWidgetDeleted" defined as true then I would stop the service and update my preferences.

Answer 4

may be answer is too late but onEnabled and onDisabled is called only when first widget is instantiated and when last widget is removed for a particular appwidget provider. Hence the above hacky and other technecs are not required.

if still you have doubts please go through the Android doc