将播放按钮更改为通知中的暂停按钮

Question

当我在我开发的播放器的通知上按下播放按钮时，我需要将播放按钮替换为暂停按钮，反之亦然。 我在我的服务类中有内部广播接收器类和方法 onPrepared，我在其中定义了通知。 在广播接收器中，我试图做这样的事情（见代码段），但我得到空指针异常。 如何通过正确暂停播放按钮来更改播放按钮？

enter code here       case _Constants.ACTION_PLAY:
                Toast.makeText(context, "Play", Toast.LENGTH_SHORT).show();
                if(isPlaying())
                {

                        status.contentView.setViewVisibility(R.drawable.icon_pause, View.INVISIBLE);
                        status.contentView.setViewVisibility(R.drawable.icon_play, View.VISIBLE);
                        pausePlayer();



                }else {

                        status.contentView.setViewVisibility(R.drawable.icon_play, View.INVISIBLE);
                        status.contentView.setViewVisibility(R.drawable.icon_pause, View.VISIBLE);
                        go();

                }

下面是 onPrepared 方法中动作按钮的声明：

enter code here
   Intent closeIntent = new Intent(this, NotificationReceiver.class).setAction(_Constants.ACTION_EXIT);
   PendingIntent pendingCloseIntent = PendingIntent.getBroadcast(this,0 ,closeIntent,PendingIntent.FLAG_UPDATE_CURRENT);

   Intent favoriteIntent = new Intent(this, NotificationReceiver.class).setAction(_Constants.ACTION_FAVORITE);
   PendingIntent pendingFavoriteIntent = PendingIntent.getBroadcast(this, 1, favoriteIntent, PendingIntent.FLAG_UPDATE_CURRENT);

   Intent prevIntent = new Intent(this,NotificationReceiver.class).setAction(_Constants.ACTION_PREVIUOS);
   PendingIntent pendingPrevIntent = PendingIntent.getBroadcast(this,2,prevIntent,PendingIntent.FLAG_UPDATE_CURRENT);

   Intent nextIntent = new Intent(this,NotificationReceiver.class).setAction(_Constants.ACTION_NEXT);
   PendingIntent pendingNextIntent = PendingIntent.getBroadcast(this,5,nextIntent,PendingIntent.FLAG_UPDATE_CURRENT);

   Intent playIntent = new Intent(this,NotificationReceiver.class).setAction(_Constants.ACTION_PLAY);
   PendingIntent pendingPlayIntent = PendingIntent.getBroadcast(this,4,playIntent,PendingIntent.FLAG_UPDATE_CURRENT);




   Bitmap artwok = BitmapFactory.decodeResource(getResources(), R.drawable.ic_player);
    status =new NotificationCompat.Builder(this,_Constants.CHANNEL_ID)

           .setSmallIcon(R.drawable.ic_music)
           .setContentTitle(songTitle)
           .setContentText(songArtist)
           .setLargeIcon(artwok)
           .setContentIntent(pendInt)
           .setOngoing(true)

           //change then null by the required intent to make it work
           .addAction(R.drawable.ic_favorite_empty,"Mark Favorite",pendingFavoriteIntent)
           .addAction(R.drawable.icon_previous, "Previous",pendingPrevIntent)
           .addAction(R.drawable.icon_play,"Play", pendingPlayIntent)
           //.addAction(R.drawable.icon_pause,"Pause",pendingPauseIntent)
           .addAction(R.drawable.icon_next,"Next",pendingNextIntent)
           .setStyle(new androidx.media.app.NotificationCompat.MediaStyle()
                   .setShowActionsInCompactView(1,2,3)
                   .setMediaSession(mediaSessionCompat.getSessionToken()))
           .addAction(R.drawable.ic_close, "EXIT",pendingCloseIntent)
           .setSubText("Now playing...")

           .build();


   status.flags=Notification.FLAG_ONGOING_EVENT;

   startForeground(1,status);

Answer 1

您可以在 xml 文件的同一位置创建 2 个按钮播放和暂停。 当您点击播放时，将其可见性设置为 GONE 并将暂停按钮 VISIBILITY 设置为 VISIBLE，反之亦然