如何防止应用程序在后台/关闭时清除Android通知？

Question

即使在应用程序关闭或在后台运行时，我也希望阻止用户关闭Android通知。仅在单击通知时将其关闭（导致应用程序启动并进入前台）。

我目前的情况是，当应用程序处于前台运行时，无法根据需要取消通知。但是，如果应用程序在后台运行或关闭，则滑动时通知会消失。

以下是用于生成通知的代码：

        Intent intent = new Intent (this, MainActivity.class);
        intent.addFlags (Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TOP);

        PendingIntent pendingIntent = PendingIntent.getActivity (this, (int) System.currentTimeMillis (), intent, PendingIntent.FLAG_UPDATE_CURRENT);

        Builder mBuilder = new Builder (this, channelIDMaxisSystems);
        Notification notification = mBuilder.setTicker (title)
                                            .setSmallIcon (R.drawable.icon)
                                            .setWhen (0)
                                            .setAutoCancel (true)
                                            .setContentTitle (title)
                                            .setContentText (content)
                                            .setContentIntent (pendingIntent)
                                            .setOngoing(true)
                                            .build ()
        ;

        notification.flags = notification.flags | Notification.FLAG_AUTO_CANCEL | Notification.FLAG_NO_CLEAR | Notification.FLAG_ONGOING_EVENT;

        NotificationManager notificationManager = (NotificationManager) this.getSystemService (Context.NOTIFICATION_SERVICE);

        notificationManager.notify (mNotificationId, notification);