android - Android 闹钟音量逐渐增大

Question

我有一个闹钟类，可以按时播放默认的闹钟铃声。我想在一段时间内播放警报音，音量从最小到最大。我怎样才能从最小到最大逐渐增加音量。是否有示例代码或项目的链接。请帮我

Answer 1

你可以自己做。里面没有什么复杂的。

一旦你PendingIntent被触发，使用处理程序来增加。

1. 创建将应用程序的AudioManager或Context作为参数的类。

     public class VolumeRunnable implements Runnable{
   
   private AudioManager mAudioManager;
   private Handler mHandlerThatWillIncreaseVolume;
   private final static int DELAY_UNTILL_NEXT_INCREASE = 30*1000;//30 seconds between each increment
   VolumeRunnable(AudioManager audioManager, Handler handler){
      this.mAudioManager = audioManager;
      this.mHandlerThatWillIncreaseVolume = handler;
   }
   
   @Override
   public void run(){
      int currentAlarmVolume = mAudioManager.getStreamVolume(AudioManager.STREAM_ALARM);
      if(currentAlarmVolume != mAudioManager.getStreamMaxVolume(AudioManager.STREAM_ALARM)){ //if we havent reached the max
   
      //here increase the volume of the alarm stream by adding currentAlarmVolume+someNewFactor
           mHandlerThatWillIncreaseVolume.postDelayed(this,DELAY_UNTILL_NEXT_INCREASE); //"recursively call this runnable again with some delay between each increment of the volume, untill the condition above is satisfied. 
      }
   
   }
   

   }

2. Runnable一旦PendingIntent触发，就调用它：

someHandler.post(new VolumeRunnable(mAudioManager, someHandler));

我希望这给了你想法。原谅任何错误或错别字。