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;
}
}
下载 http://download.csdn.net/detail/chenchuntong/5268025