Android ActivityLifecycle 生命周期管理一些常用的功能实现需要ActivityLifecycle

一些常用的功能实现需要ActivityLifecycle 生命周期回调才能更好的实现：

应用切换或被三方应用遮挡时，需要给出提示；
业务流程需要在A-B-C-D-...-Z 时，关闭D-Z过程的界面；

自定义ActivityLifecycle生命周期回调单例实现类

public class ActivityManager implements Application.ActivityLifecycleCallbacks {    private static final class ActivityManagerHolder {        private static final ActivityManager INSTANCE = new ActivityManager();    }    public static ActivityManager getInstance() {        return ActivityManagerHolder.INSTANCE;    }    @Override    public void onActivityCreated(Activity activity, Bundle savedInstanceState) {    }    @Override    public void onActivityStarted(Activity activity) {    }    @Override    public void onActivityResumed(Activity activity) {    }    @Override    public void onActivityPaused(Activity activity) {    }    @Override    public void onActivityStopped(Activity activity) {    }    @Override    public void onActivitySaveInstanceState(Activity activity, Bundle outState) {    }    @Override    public void onActivityDestroyed(Activity activity) {    }}

自定义MainApplication注册ActivityLifecycleCallbacks

public class MainApplication extends Application {    @Override    public void onCreate() {        super.onCreate();        registerActivityLifecycleCallbacks(ActivityManager.getInstance());    }}