Android 实时监听Activity堆栈变化（系统应用）

    private val mIActivityManager: IActivityManager = ActivityManagerNative.asInterface(ServiceManager.getService(Context.ACTIVITY_SERVICE))

方式一（registerProcessObserver） ：

mIActivityManager.registerProcessObserver(mIProcessObserverStub)private val mIProcessObserverStub = object : IProcessObserver.Stub(){override fun onForegroundActivitiesChanged(pid: Int,uid: Int,foregroundActivities: Boolean) {// 栈发生变化}override fun onForegroundServicesChanged(pid: Int, uid: Int, serviceTypes: Int) {}override fun onProcessDied(pid: Int, uid: Int) {}}

方式二（registerTaskStackListener）： 

        mIActivityManager.registerTaskStackListener(object : TaskStackListener(){override fun onTaskStackChanged() {super.onTaskStackChanged()dLog("$TAG onTaskStackChanged...")}})

权限添加： 

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