public class App extends Application {
    private static Context mContext;
    private static ActivityManager activityManager = null; // activity管理類

    public static Context getAppContext() {
        return mContext;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        mContext = getApplicationContext();
        activityManager = getManagerInstance(); // 獲得實例
    }

    public static ActivityManager getActivityManager() {
        return activityManager;
    }


    public ActivityManager getManagerInstance() {
        if (activityManager != null) {
            return activityManager;
        } else {
            return activityManager = new ActivityManager();
        }
    }

    /**
     * activity管理類**********************************************
     */
    public class ActivityManager {
        /**
         * 接收activity的Stack
         */
        private Stack<Activity> activityStack = null;

        private ActivityManager() {
        }

     /**
         * 將activity推入棧內
         *
         * @param activity
         */
        public void pushActivity(Activity activity) {
            if (activityStack == null) {
                activityStack = new Stack<Activity>();
            }
            activityStack.add(activity);
        }

        /**
         * 將activity移出棧
         *
         * @param activity
         */
        public void popActivity(Activity activity) {
            if (activity != null) {
                activityStack.remove(activity);
            }
        }

        /**
         * 結束指定activity
         *
         * @param activity
         */
        public void endActivity(Activity activity) {
            if (activity != null) {
                activity.finish();
                activityStack.remove(activity);
                activity = null;
            }
        }

        /**
         * 獲得當前的activity(即最上層)
         *
         * @return
         */
        public Activity currentActivity() {
            Activity activity = null;
            if (!activityStack.empty())
                activity = activityStack.lastElement();
            return activity;
        }

        /**
         * 彈出除cls外的所有activity
         *
         * @param cls
         */
        public void popAllActivityExceptOne(Class<? extends Activity> cls) {
            while (true) {
                Activity activity = currentActivity();
                if (activity == null) {
                    break;
                }
                if (activity.getClass().equals(cls)) {
                    break;
                }
                popActivity(activity);
            }
        }

        /**
         * 結束除cls之外的所有activity,執行結果都會清空Stack
         *
         * @param cls
         */
        public void finishAllActivityExceptOne(Class<? extends Activity> cls) {
            while (!activityStack.empty()) {
                Activity activity = currentActivity();
                if (activity.getClass().equals(cls)) {
                    popActivity(activity);
                } else {
                    endActivity(activity);
                }
            }
        }

        /**
         * 結束所有activity
         */
        public void finishAllActivity() {
            while (!activityStack.empty()) {
                Activity activity = currentActivity();
                endActivity(activity);
            }
        }
    }
}