Android中音频管理--AudioFocus机制使用说明

AudioFocus 机制说明

一、 说明

   Android 2.2引入了称作AudioFocus的机制来管理对Audio资源的竞争的管理与协调。 按照AudioFocus的机制，在使用AudioStream之前，需要申请AudioFocus，在获得AudioFocus之后才可以使用相应的AudioStream；如果有别的程序竞争你正在使用的AudioStream，你的程序需要在收到通知之后做停止播放或者降低声音的处理。该机制需要合作完成。

 

二、 使用方法介绍

 

1.音频的播放

 

AudioManager am = mContext.getSystemService(Context.AUDIO_SERVICE);
...

// Request audio focus for playback
int result = am.requestAudioFocus(afChangeListener,
                                 // Use the music stream.
                                 AudioManager.STREAM_MUSIC,
                                 // Request permanent focus.
                                 AudioManager.AUDIOFOCUS_GAIN);
   
if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
        // Start playback.
}

2.播放完成的释放

 

// Abandon audio focus when playback complete    
 am.abandonAudioFocus(afChangeListener);

3.Focus改变的监听

OnAudioFocusChangeListener afChangeListener = new OnAudioFocusChangeListener() {
    public void onAudioFocusChange(int focusChange) {
        if (focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT //临时失焦
            // Pause playback
        } else if (focusChange == AudioManager.AUDIOFOCUS_GAIN) { //获取焦点
            // Resume playback 
        } else if (focusChange == AudioManager.AUDIOFOCUS_LOSS) {
            am.abandonAudioFocus(afChangeListener);
            // Stop playback
        }
    }
};

 

三、AudioFocus机制时序图

四、使用代码示例

 

 

public static void init(Context context) {

mContext = context;

AudioManager am = (AudioManager) mContext.getSystemService(Context.AUDIO_SERVICE);

int result = am.requestAudioFocus(, AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN);

if(result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED){

startPlay();

}

}

 

OnAudioFocusChangeListener afChangeListener = new OnAudioFocusChangeListener() {

public void onAudioFocusChange(int focusChange) {

            if (focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT) {//临时失焦

            // Pause playback

             pausePlay();

        } 

        else if (focusChange == AudioManager.AUDIOFOCUS_GAIN) { //获取焦点

            // Resume playback 

         resumePlay();

        } 

        else if (focusChange == AudioManager.AUDIOFOCUS_LOSS) {

           am.abandonAudioFocus(afChangeListener);

           // Stop playback

              stopPlay();

        }

     }

};

五、使用帮助类AudioFocusHelper

package com.utility.helper;import com.utility.common.LogHelper;import android.content.Context;import android.media.AudioManager;import android.media.AudioManager.OnAudioFocusChangeListener;public class AudioFocusHelper {private static Context mContext;private static final String TAG = "AudioFocusHelper";private volatile static AudioFocusHelper instance; // 实例private OnAudioFocusChangeListener mAudioFocusChangeListener;private AudioManager mAudioManager;private static final int AUDIO_NO_FOCUS_NO_DUCK = 0;private static final int AUDIO_FOCUSED  = 2;private int mAudioFocus = AUDIO_NO_FOCUS_NO_DUCK;public static AudioFocusHelper getInstance(Context context) {mContext = context;if (instance == null) {synchronized (AudioFocusHelper.class) {if (instance == null) {instance = new AudioFocusHelper();}}}return instance;}private AudioFocusHelper() {if(null != mContext){mAudioManager = (AudioManager) mContext.getSystemService(Context.AUDIO_SERVICE);}}/** * 设置 audiofocus changelistener,只调一次 */public void setAudioFocusChangeListener(OnAudioFocusChangeListener listener){if(null == mAudioManager && null != mContext){mAudioManager = (AudioManager) mContext.getSystemService(Context.AUDIO_SERVICE);}mAudioFocusChangeListener = listener;LogHelper.releaseLog(TAG, "setAudioFocusChangeListener");}/** * get AudioFocus,播放前调用,需先调用setAudioFocusChangeListener * return true: focus success */public boolean startFocus(){LogHelper.releaseLog(TAG, "startFocus");if(null != mAudioManager && mAudioFocus != AUDIO_FOCUSED){int result = mAudioManager.requestAudioFocus(mAudioFocusChangeListener, AudioManager.STREAM_MUSIC,                AudioManager.AUDIOFOCUS_GAIN);if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {                mAudioFocus = AUDIO_FOCUSED;            }}if(mAudioFocus == AUDIO_FOCUSED){return true;}else{return false;}}/** * give up AudioFocus，播放完成调用 * return true: stop success */public boolean stopFocus(){LogHelper.releaseLog(TAG, "stopFocus");if (null != mAudioManager && mAudioFocus == AUDIO_FOCUSED) {            if (mAudioManager.abandonAudioFocus(mAudioFocusChangeListener) == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {                mAudioFocus = AUDIO_NO_FOCUS_NO_DUCK;            }        }if(mAudioFocus == AUDIO_NO_FOCUS_NO_DUCK){return true;}else{return false;}}/** * 释放资源 */public void release(){mAudioManager = null;instance = null;}}

六、AudioFocusHelper使用说明

一、说明

Helios应用在播放音频时需要统一使用CommonSDK中的AudioFocusHelper获取AudioStream，并设置监听，实用完成后释放AudioStream.

权限：android.permission.MODIFY_AUDIO_SETTINGS

二、使用方法

1.设置OnAudioFocusChangeListener监听，方法如下：

AudioFocusHelper.getInstance(mContext).setAudioFocusChangeListener(OnAudioFocusChangeListener listener);

2.播放前调用startFocus方法，如下：

AudioFocusHelper.getInstance(getApplicationContext()).startFocus();

返回true:获取AudioStream成功，false：失败

3.播放完成后调用stopFocus方法，如下：

AudioFocusHelper.getInstance(getApplicationContext()).stopFocus();

返回true:释放AudioStream成功，false：失败

三、OnAudioFocusChangeListener监听说明

示例：

public void onAudioFocusChange(int focusChange) {

 if (focusChange == AudioManager.AUDIOFOCUS_GAIN ) {

//获取焦点

} 

else if (focusChange == AudioManager.AUDIOFOCUS_LOSS || focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT ||focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK

) {

//失去焦点

 }

}

四、注意

开始播放音频前，需要调用startFocus,返回成功即可播放，失败不播放。结束播放时，需要调用stopFocus。