Android 更好的Activity生命周期回调

/**
 * This class allows you to listen to when the user is entering the background (i.e. after a home button press,
 * or opening recent apps etc) and when the user resumes the application from the background.
 *
 * @author John McDonnell
 */
public class BetterActivityLifecycleCallbacks implements Application.ActivityLifecycleCallbacks {

    private int mForegroundActivities;
    private boolean mHasSeenFirstActivity;
    private boolean mChangingConfiguration;

    @Override public void onActivityCreated(Activity activity, Bundle savedInstanceState) {

    }

    @Override public void onActivityStarted(Activity activity) {
        mForegroundActivities++;

        if (mHasSeenFirstActivity && mForegroundActivities == 1 && !mChangingConfiguration) {
            applicationDidEnterForeground(activity);
        }

        mHasSeenFirstActivity = true;
        mChangingConfiguration = false;
    }

    @Override public void onActivityResumed(Activity activity) {

    }

    @Override public void onActivityPaused(Activity activity) {

    }

    @Override public void onActivityStopped(Activity activity) {
        mForegroundActivities--;

        if (mForegroundActivities == 0) {
            applicationDidEnterBackground(activity);
        }

        mChangingConfiguration = activity.isChangingConfigurations();
    }

    @Override public void onActivitySaveInstanceState(Activity activity, Bundle outState) {

    }

    @Override public void onActivityDestroyed(Activity activity) {

    }

    /**
     * One day we'll be as cool as iOS
     */
    protected void applicationDidEnterForeground(Activity topActivity) {

    }

    protected void applicationDidEnterBackground(Activity lastActivity) {

    }

}