用于监听App程序的生命周期。
ApplicationObserver类：
class ApplicationObserver: LifecycleObserver { }
DemoApplication类：
class DemoApplication : Application() { override fun onCreate() { super.onCreate() ProcessLifecycleOwner.get().lifecycle.addObserver(ApplicationObserver()) } }
Android Jetpack架构之ProcessLifeCycleOwner
原文：https://www.cnblogs.com/naray/p/15200113.html