参考：http://mindtherobot.com/blog/624/android-audio-play-an-mp3-file-on-an-audiotrack/
http://baike.baidu.com/view/14471.htm
建议下载一个铃声文件（小点的），然后用千千静听，转换成wav格式的。
源码如下：
public class Playmp3Activity extends Activity {
private final String file="//sdcard//testring.wav";
private final static String tag="22";
static byte[] buffer=null;
AudioTrack at=null;
int pcmlen=0;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
try {
FileInputStream fis=new FileInputStream(file);
buffer=new byte[1024*1024*2];//2M
int len=fis.read(buffer);
Log.i(tag, "fis len="+len);
Log.i(tag, "0:"+(char)buffer[0]);
pcmlen=0;
pcmlen+=buffer[0x2b];
pcmlen=pcmlen*256+buffer[0x2a];
pcmlen=pcmlen*256+buffer[0x29];
pcmlen=pcmlen*256+buffer[0x28];
int channel=buffer[0x17];
channel=channel*256+buffer[0x16];
int bits=buffer[0x23];
bits=bits*256+buffer[0x22];
Log.i(tag, "pcmlen="+pcmlen+",channel="+channel+",bits="+bits);
at = new AudioTrack(AudioManager.STREAM_MUSIC, 44100,
channel,
AudioFormat.ENCODING_PCM_16BIT,
pcmlen,
AudioTrack.MODE_STATIC);
at.write(buffer, 0x2C, pcmlen);
Log.i(tag, "write 1...");
at.play();
Log.i(tag, "play 1...");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
at.release();
}
}