音量变化监听器? [英] Volume change listener?

问题描述

有没有办法通过 Android 服务监听音量变化并做出反应?

Is there any way to listen for volume changes with an Android service and react to that?

顺便说一句:即使音乐在后台播放，Google 音乐应用程序如何允许用户控制媒体音量?

Btw: How does the Google music app allow the user to control the media volume even when the music is playing in the background?

推荐答案

查看registerMediaButtonEventReceiver(ComponentName broadcastReceiver);

定义处理 ACTION_MEDIA_BUTTON 的 BroadcastReceiver.收到的 intent 包括一个额外的字段，EXTRA_KEY_EVENT，包含导致广播的关键事件.您可以使用此键事件来获取按下了哪个键.

Define a BroadcastReceiver that handles ACTION_MEDIA_BUTTON. The recieved intent includes a single extra field, EXTRA_KEY_EVENT, containing the key event that caused the broadcast. You can use this key event to get which key was pressed.

这只是一个示例代码.可能存在语法错误.

This is just a sample code. syntax errors may be there.

// in onCreate of activity
registerMediaButtonEventReceiver(mediaReceiver ); 

// later somewhere in activity.
MediaButton_Receiver mediaReceiver = new MediaButton_Receiver();

class MediaButton_Receiver implements BroadcastReceiver {
     void onReceive(Intent intent) {

          KeyEvent ke = (KeyEvent)intent.getExtra(Intent.EXTRA_KEY_EVENT); 
          if (ke .getKeyCode() == KeyEvent.KEYCODE_VOLUME_DOWN) {

          }
          // Similarly other key codes .......
     } 
}

在 onPause() 或 onStop()

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