安卓-音频焦点

- 音频焦点
- - 是什么
  - 怎么做

音频焦点

是什么

一个安卓系统肯定会有多个音源，音频焦点是用来处理这些音源的冲突

eg 在播放网易云的时候打开抖音网易云会自动暂停并且网易云有提醒其实是网易云做了处理

发者需要明确编写代码来请求和处理音频焦点的变化。

怎么做

主要涉及这2个对象

kotlin 复制代码

private var audioFocusRequest: AudioFocusRequest? = null
private var audioManager: AudioManager? = null

主要的要做的工作有3个

1.当应用开始播放音频时，开发者需要通过 AudioManager 请求音频焦点：

kotlin 复制代码

  if (audioFocus) { //audioFocus是自定义bool
            doPlaying()
        }else {
            val result = audioManager!!.requestAudioFocus(audioFocusRequest!!)
            if (result == AudioManager.AUDIOFOCUS_GAIN) {
                doPlaying()
                audioFocus = true
            }
        }

2.处理音频焦点变化：

就是实现OnAudioFocusChangeListener 并且set进去

kotlin 复制代码

        val audioFocusChangeListener = AudioManager.OnAudioFocusChangeListener { focusChange: Int ->
             when (focusChange) {
                 AudioManager.AUDIOFOCUS_GAIN -> {
                     audioFocus = true
                     play()
                     Log.d(TAG, "AUDIO_FOCUS_GAIN")
                 }
                 AudioManager.AUDIOFOCUS_LOSS -> {
                     audioFocus = false
                     pause()
                     Log.d(TAG, "AUDIO_FOCUS_LOSS")
                 }
                 AudioManager.AUDIOFOCUS_LOSS_TRANSIENT -> {
                     audioFocus = false
                     pause()
                     Log.d(TAG, "AUDIO_FOCUS_LOSS_TRANSIENT")
                 }
                 AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK ->
                     Log.d(TAG, "AUDIO_FOCUS_LOSS_TRANSIENT_CAN_DUCK")
             }
         }
  audioFocusRequest = AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN)
             .setAudioAttributes(AudioAttributes.Builder().setUsage(AudioAttributes.USAGE_MEDIA).build())
             .setOnAudioFocusChangeListener(audioFocusChangeListener)
             .build()

3.放弃音频焦点：当你的应用不再需要播放音频时

音乐暂停或者应用销毁等等

kotlin 复制代码

            audioManager!!.abandonAudioFocusRequest(audioFocusRequest!!)