ActivityLifecycleCallbacks是什么？
- Application通过此接口提供了一套回调方法，用于让开发人员对Activity的生命周期事件进行集中处理。
为什么用ActivityLifecycleCallbacks？
- 以往若需监測Activity的生命周期事件代码，你可能是这样做的。重写每个Acivity的onResume()，然后作统计和处理：
@Overrideprotected void onResume() { super.onResume(); //TODO 处理和统计代码 Log.v(TAG, "onResume"); Logger.v(TAG, "onResume"); Logging.v(TAG, "onResume"); ...} - ActivityLifecycleCallbacks接口回调能够简化这一繁琐过程。在一个类中作统一处理
ActivityLifecycleCallbacks怎么用？
- android.app.Application.ActivityLifecycleCallbacks
- 要求API 14+ （Android 4.0+）
- 继承Application
public class BaseApplication extends Application
- 在AndroidManifest里起用自己定义Application
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重写Application的onCreate()方法，或在Application的无參构造方法内，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"); } });}; -
执行结果(Logcat日志)
10-21 14:32:57.722: V/WelcomeActivity(8085): onActivityCreated10-21 14:32:57.762: V/WelcomeActivity(8085): onActivityStarted10-21 14:32:57.762: V/WelcomeActivity(8085): onActivityResumed10-21 14:32:59.164: V/WelcomeActivity(8085): onActivityPaused10-21 14:32:59.194: V/MainActivity(8085): onActivityCreated10-21 14:32:59.224: V/MainActivity(8085): onActivityStarted10-21 14:32:59.224: V/MainActivity(8085): onActivityResumed10-21 14:32:59.735: V/WelcomeActivity(8085): onActivityStopped10-21 14:32:59.735: V/WelcomeActivity(8085): onActivityDestroyed10-21 14:33:06.502: V/MainActivity(8085): onActivityPaused10-21 14:33:06.612: V/MainActivity(8085): onActivityStopped10-21 14:33:06.612: V/MainActivity(8085): onActivityDestroyed
ActivityLifecycleCallbacks的拓展使用方法
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本次初探仅尝试使用Log日志工具作简要測试。如需满足较复杂的统计或调试需求时。此法可能会大大降低插入代码量，提高效率
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API仅在14+版本号上提供此接口回调，
- API仅针对上述几个Activity的生命周期事件留出了接口回调，可能已无法满足日益过渡为使用Fragment的今日需求。