ActivityLifecycleCallbacks
4.0（API Level 14）新增了一个Application接口ActivityLifecycleCallbacks
Application通过此接口提供了一套回调方法，用于让开发者对Activity的生命周期事件进行集中处理。
为什么用ActivityLifecycleCallbacks？
以往若需监测Activity的生命周期事件代码，你可能是这样做的，重写每一个Acivity的onResume()
重写Application的onCreate()方法，或在Application的无参构造方法内，调用Application.registerActivityLifecycleCallbacks()方法，并实现ActivityLifecycleCallbacks接口
public void onCreate() {
super.onCreate();
this.registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {
@Override
public void onActivityStopped(Activity activity) {
Logger.v(activity, “onActivityStopped”);
}
@Override
public void onActivityStarted(Activity activity) {
Logger.v(activity, “onActivityStarted”);
}
@Override
public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
Logger.v(activity, “onActivitySaveInstanceState”);
}
@Override
public void onActivityResumed(Activity activity) {
Logger.v(activity, “onActivityResumed”);
}
@Override
public void onActivityPaused(Activity activity) {
Logger.v(activity, “onActivityPaused”);
}
@Override
public void onActivityDestroyed(Activity activity) {
Logger.v(activity, “onActivityDestroyed”);
}
@Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
Logger.v(activity, “onActivityCreated”);
}
});
};
应用：ActivityManager:
public class ActivityManager implements Application.ActivityLifecycleCallbacks {
private static ActivityManager manager = new ActivityManager();
public static ActivityManager get () {
return manager;
}
private LinkedList stack = new LinkedList<>();
@Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
if (!stack.contains(activity)) {
stack.add(activity);
}
}
@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) {
if (stack.contains(activity)) {
stack.remove(activity);
}
}
public Activity topActivity () {
Activity activity = null;
if (!stack.isEmpty()) {
activity = stack.getLast();
}
return activity;
}
public void registerSelf(Context context) {
Application application = (Application) context.getApplicationContext();
application.registerActivityLifecycleCallbacks(ActivityManager.get());
}