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