android中使用notification的时候，点击home键，再从通知选项中返回点击home键前那个activity

NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        Notification notification = new Notification(R.drawable.ic_launcher,
                "Hello,there!", System.currentTimeMillis());
        notification.flags = Notification.FLAG_AUTO_CANCEL;

        Intent intent = new Intent(this, NotWorkActivity.class);//注意这里!!!

        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP
                | Intent.FLAG_ACTIVITY_NEW_TASK);
        PendingIntent contentIntent = PendingIntent.getActivity(this,
                R.string.app_name, intent, PendingIntent.FLAG_UPDATE_CURRENT);
        notification.setLatestEventInfo(this, "Hello,there!", "Hello,there,I‘m john.",
                contentIntent);
        notificationManager.notify(0, notification);

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
//就一句话！！
        this.finish();
    }