java 音乐暂停_java – JLayer – 暂停和恢复歌曲
一个非常简单的播放器实现,真正暂停播放.它的工作原理是使用一个单独的线程来播放流并告诉玩家线程是否/何时暂停和恢复.
public class PausablePlayer {
private final static int NOTSTARTED = 0;
private final static int PLAYING = 1;
private final static int PAUSED = 2;
private final static int FINISHED = 3;
// the player actually doing all the work
private final Player player;
// locking object used to communicate with player thread
private final Object playerLock = new Object();
// status variable what player thread is doing/supposed to do
private int playerStatus = NOTSTARTED;
public PausablePlayer(final InputStream inputStream) throws JavaLayerException {
this.player = new Player(inputStream);
}
public PausablePlayer(final InputStream inputStream, final AudioDevice audioDevice) throws JavaLayerException {
this.player = new Player(inputStream, audioDevice);
}
/**
* Starts playback (resumes if paused)
*/
public void play() throws JavaLayerException {
synchronized (playerLock) {
switch (playerStatus) {
case NOTSTARTED:
final Runnable r = new Runnable() {
public void run() {
playInternal();
}
};
final Thread t = new Thread(r);
t.setDaemon(true);
t.setPriority(Thread.MAX_PRIORITY);
playerStatus = PLAYING;
t.start();
break;
case PAUSED:
resume();
break;
default:
break;
}
}
}
/**
* Pauses playback. Returns true if new state is PAUSED.
*/
public boolean pause() {
synchronized (playerLock) {
if (playerStatus == PLAYING) {
playerStatus = PAUSED;
}
return playerStatus == PAUSED;
}
}
/**
* Resumes playback. Returns true if the new state is PLAYING.
*/
public boolean resume() {
synchronized (playerLock) {
if (playerStatus == PAUSED) {
playerStatus = PLAYING;
playerLock.notifyAll();
}
return playerStatus == PLAYING;
}
}
/**
* Stops playback. If not playing, does nothing
*/
public void stop() {
synchronized (playerLock) {
playerStatus = FINISHED;
playerLock.notifyAll();
}
}
private void playInternal() {
while (playerStatus != FINISHED) {
try {
if (!player.play(1)) {
break;
}
} catch (final JavaLayerException e) {
break;
}
// check if paused or terminated
synchronized (playerLock) {
while (playerStatus == PAUSED) {
try {
playerLock.wait();
} catch (final InterruptedException e) {
// terminate player
break;
}
}
}
}
close();
}
/**
* Closes the player, regardless of current state.
*/
public void close() {
synchronized (playerLock) {
playerStatus = FINISHED;
}
try {
player.close();
} catch (final Exception e) {
// ignore, we are terminating anyway
}
}
// demo how to use
public static void main(String[] argv) {
try {
FileInputStream input = new FileInputStream("myfile.mp3");
PausablePlayer player = new PausablePlayer(input);
// start playing
player.play();
// after 5 secs, pause
Thread.sleep(5000);
player.pause();
// after 5 secs, resume
Thread.sleep(5000);
player.resume();
} catch (final Exception e) {
throw new RuntimeException(e);
}
}
}