Android AudioManager获取媒体焦点
平时开发的时候 遇到这样的一个问题: 我开着系统的音乐播放器，我在我的应用程序里面播一段音乐 两个音乐会同时播放通过在stackoverflow查资料后才发行我们得自己音乐需要获取焦点，在我们音乐播完了以后释放掉焦点。这样系统的歌曲会继续播放下面介绍一下步骤
1.获取AudioManager对象
AudioManager am = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
2. 注册OnAudioFocusChangeListener监听
OnAudioFocusChangeListener afChangeListener = new OnAudioFocusChangeListener() {
public void onAudioFocusChange(int focusChange) {
if (focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT) {
if(mediaPlayer.isPlaying()){
mediaPlayer.pause();
}
} else if (focusChange == AudioManager.AUDIOFOCUS_GAIN) {
if(mediaPlayer==null){
initBeepSound();
}else if(!mediaPlayer.isPlaying()){
mediaPlayer.start();
}
// Resume playback
} else if (focusChange == AudioManager.AUDIOFOCUS_LOSS) {
if(mediaPlayer.isPlaying()){
mediaPlayer.stop();
}
am.abandonAudioFocus(afChangeListener);
// Stop playback
}else if(focusChange==AudioManager.AUDIOFOCUS_REQUEST_GRANTED){
if (mediaPlayer.isPlaying()) {
mediaPlayer.stop();
}
}else if(focusChange==AudioManager.AUDIOFOCUS_REQUEST_FAILED){
if(mediaPlayer.isPlaying()){
mediaPlayer.stop();
}
}
}
};
3.就是在我们播放音乐的时候为AudioManager添加获取焦点的监听
int result = am.requestAudioFocus(afChangeListener,
// Use the music stream.
AudioManager.STREAM_MUSIC, // Request permanent focus.
AudioManager.AUDIOFOCUS_GAIN);
if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
mediaPlayer.start();
// Start playback. // 开始播放音乐文件
}
4.在我们不用的时候将焦点释放掉一般我们是在ondestroy()方法中释放
@Override
protected void onStop() {
// TODO Auto-generated method stub
super.onStop();
am.abandonAudioFocus(afChangeListener);
}
下面介绍一下AudioManager的几个常量
AUDIOFOCUS_REQUEST_GRANTED 永久获取媒体焦点（播放音乐）
AUDIOFOCUS_GAIN_TRANSIENT 暂时获取焦点 适用于短暂的音频
AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK Duck我们应用跟其他应用共用焦点 我们播放的时候其他音频会降低音量
下面奉上代码:
package com.example.mediatest; import java.io.IOException; import android.app.Activity; import android.content.BroadcastReceiver; import android.content.ComponentName; import android.content.Context; import android.content.Intent; import android.content.res.AssetFileDescriptor; import android.media.AudioManager; import android.media.AudioManager.OnAudioFocusChangeListener; import android.media.MediaPlayer; import android.media.MediaPlayer.OnCompletionListener; import android.os.Bundle; import android.view.KeyEvent; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.Toast; public class MainActivity extends Activity { private Button play; private Button stop; private AudioManager am; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); play = (Button) findViewById(R.id.button1); stop = (Button) findViewById(R.id.button2); am = (AudioManager) getSystemService(Context.AUDIO_SERVICE); initBeepSound(); mode = am.getMode(); if (mode == AudioManager.MODE_NORMAL) { Toast.makeText(this, "MODE_NORMAL", Toast.LENGTH_LONG).show(); } else if (mode == AudioManager.MODE_IN_CALL) { Toast.makeText(this, "MODE_IN_CALL", Toast.LENGTH_LONG).show(); } else if (mode == AudioManager.MODE_RINGTONE) { Toast.makeText(this, "MODE_RINGTONE", Toast.LENGTH_LONG).show(); } remoteControlReceiver = new ComponentName(" com.example.mediatest", " com.example.mediatest.RemoteControlReceiver"); play.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if (mediaPlayer != null) { mediaPlayer.start(); } else { initBeepSound(); mediaPlayer.start(); } // Request audio focus for playback int result = am.requestAudioFocus(afChangeListener, // Use the music stream. AudioManager.STREAM_MUSIC, // Request permanent focus. AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK); if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) { mediaPlayer.start(); // Start playback. // 开始播放音乐文件 } } }); stop.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if (mediaPlayer != null && mediaPlayer.isPlaying()) { mediaPlayer.stop(); mediaPlayer.release(); mediaPlayer = null; } am.abandonAudioFocus(afChangeListener); } }); } OnAudioFocusChangeListener afChangeListener = new OnAudioFocusChangeListener() { public void onAudioFocusChange(int focusChange) { if (focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT) { if (mediaPlayer.isPlaying()) { mediaPlayer.pause(); } } else if (focusChange == AudioManager.AUDIOFOCUS_GAIN) { if (mediaPlayer == null) { initBeepSound(); } else if (!mediaPlayer.isPlaying()) { mediaPlayer.start(); } // Resume playback } else if (focusChange == AudioManager.AUDIOFOCUS_LOSS) { if (mediaPlayer.isPlaying()) { mediaPlayer.stop(); } am.abandonAudioFocus(afChangeListener); // Stop playback } else if (focusChange == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) { if (mediaPlayer.isPlaying()) { mediaPlayer.stop(); } } else if (focusChange == AudioManager.AUDIOFOCUS_REQUEST_FAILED) { if (mediaPlayer.isPlaying()) { mediaPlayer.stop(); } } } }; /** * When the beep has finished playing, rewind to queue up another one. */ private final OnCompletionListener beepListener = new OnCompletionListener() { public void onCompletion(MediaPlayer mediaPlayer) { mediaPlayer.seekTo(0); } }; private MediaPlayer mediaPlayer; private ComponentName remoteControlReceiver; private int mode; private void initBeepSound() { if (mediaPlayer == null) { // The volume on STREAM_SYSTEM is not adjustable, and users found it // too loud, // so we now play on the music stream. setVolumeControlStream(AudioManager.STREAM_MUSIC); mediaPlayer = new MediaPlayer(); mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); mediaPlayer.setOnCompletionListener(beepListener); AssetFileDescriptor file = getResources().openRawResourceFd( R.raw.demo); try { mediaPlayer.setDataSource(file.getFileDescriptor(), file.getStartOffset(), file.getLength()); file.close(); mediaPlayer.prepare(); } catch (IOException e) { mediaPlayer = null; } } } @Override protected void onStop() { // TODO Auto-generated method stub super.onStop(); am.abandonAudioFocus(afChangeListener); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } }
linker : http://blog.csdn.net/chenchuntong/article/details/8813719