为什么我选新歌的时候音乐不停止?

Question

我正在用Java编写一个程序，其中每次用户按下键盘上的按钮时，都会播放一首歌。然而，当我进行测试时，按下这些键会让歌曲一个接一个地播放，而不是在播放另一首之前停止播放。以下是我在播放器中的代码:

import javax.swing.*;
import javax.sound.sampled.*;
import java.io.*;
public class Player
{
public void playmusic(String musicfile) {
File soundFile = new File(musicfile);
try {
Clip clip = AudioSystem.getClip();
if(musicfile.equals("stop")){
clip.stop();
}
else {
AudioInputStream inputStream= AudioSystem.getAudioInputStream(soundFile);
clip.open(inputStream);
//clip.loop(clip.LOOP_CONTINUOUSLY);
clip.start();
}
}
catch(Exception e)
{
System.out.println(e);
}
}
}

在我的Game类中，我创建了一个名为play的Player类实例。下面是类(与音乐相关的方法是keyPressed()):

import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage; 
import java.awt.event.*; 
public class Game  extends JPanel implements Runnable, KeyListener{

private BufferedImage back; 
private int key; 
private String[] song;
private Player play;
private ImageIcon menu, choose;
private String screen;

public Game() {
new Thread(this).start();   
this.addKeyListener(this);
key =-1; 
play = new Player();
song = new String[]{"the_greatest_show.wav","a_million_dreams.wav","a_million_dreams_reprise.wav","come_alive.wav","the_other_side.wav","never_enough.wav","this_is_me.wav","rewrite_the_star.wav","tightrope.wav", "never_enough_reprise.wav","from_now_on.wav"};
letter = 'Z';
menu = new ImageIcon("menu.png");
choose = new ImageIcon("select.png");
screen = "Menu";
}

public void run()
{
try
{
while(true)
{
Thread.currentThread().sleep(5);
repaint();
}
}
catch(Exception e)
{
}
}


public void paint(Graphics g){
Graphics2D twoDgraph = (Graphics2D) g; 
if( back ==null)
back=(BufferedImage)( (createImage(getWidth(), getHeight()))); 

Graphics g2d = back.createGraphics();
g2d.clearRect(0,0,getSize().width, getSize().height);
switch(screen){
case("Menu"):
g2d.drawImage(menu.getImage(), 0, 0, 1000, 700, this);
break;
case("Choose"):
g2d.drawImage(choose.getImage(), 0, 0, 1000, 700, this);

}
twoDgraph.drawImage(back, null, 0, 0);
}

public void stopMusic(){
play.playmusic("stop");
}


@Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}


@Override
public void keyPressed(KeyEvent e) {
// TODO Auto-generated method stub
key= e.getKeyCode();
char c = (char)(key);
switch(c){
case 'A':
stopMusic();
play.playmusic(song[0]);
break;
case 'S':
stopMusic();
play.playmusic(song[1]);
break;

case 'D':
stopMusic();
play.playmusic(song[2]);
break;
case 'F':
stopMusic();
play.playmusic(song[3]);
break;
case 'G':
stopMusic();
play.playmusic(song[4]);
break;
case 'H':
stopMusic();
play.playmusic(song[5]);
break;
case 'J':
stopMusic();
play.playmusic(song[6]);
break;
case 'K':
stopMusic();
play.playmusic(song[7]);
break;
case 'L': 
stopMusic();
play.playmusic(song[8]);
break;
case 'V':
stopMusic();
play.playmusic(song[9]);
break;
case 'B':
stopMusic();
play.playmusic(song[10]);
break;
default:
stopMusic();
}
}

@Override
public void keyReleased(KeyEvent e) {
}

}

请帮我解决这个问题。提前谢谢你。

Answer 1

如果调用getClip()在该方法中，您将停止第二个剪辑，因为您丢失了对前一个剪辑的引用(并将继续在后台播放)。AudioSystem.getClip()返回new剪辑，而不是当前的。

当您播放下一首歌曲时，您同时播放两个片段:第一个和当前一个，因为您停止的那个是一个新的。

Clip[0]      Clip[1]         Clip[2]
Song 1   (nosong-stopped)    Song 2

为了解决这个问题，你可以让clip成为一个全局变量，所以当stop()和close()被调用时，当前歌曲的clip是被选中的(你将只有一个剪辑)。

Clip clip = null;
//...
public void playmusic(String musicfile) {
File soundFile = new File(musicfile);
try 
{
if(musicfile.equals("stop")) 
{
if (clip!=null) //do not nest it to the previous condition ...
{
clip.stop();
clip.flush();
clip.close();
}
}
else   //...so no song is played if you called stop and clip was null
{
AudioInputStream inputStream= AudioSystem.getAudioInputStream(soundFile);
if (clip == null || !clip.isOpen())
clip = AudioSystem.getClip();
clip.open(inputStream);
//clip.loop(clip.LOOP_CONTINUOUSLY);
clip.start();
}
}
catch(Exception e)
{
System.out.println(e);
}
}

Answer 2

替换playmusic()方法并检查

public void playmusic(String musicfile) {

try {
Clip clip = AudioSystem.getClip();
if(musicfile.equals("stop")){
clip.stop();
}
else {
File soundFile = new File(musicfile);
AudioInputStream inputStream= AudioSystem.getAudioInputStream(soundFile);
clip.open(inputStream);
//clip.loop(clip.LOOP_CONTINUOUSLY);
clip.start();
}
}
catch(Exception e)
{
System.out.println(e);
}
}