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我制作了这个程序来在 java 中播放 mp3 文件。以下代码播放 mp3 文件,但在播放时无法停止...我在两个按钮上添加了两个单独的 ActionListener 但它不适用于停止按钮...

import java.io.*;    
import javax.swing.*;
import java.awt.event.*;
import javazoom.jl.player.Player;  
import java.io.FileInputStream;



    public class Play2 extends JFrame
    {  
    JButton b,b1;
    JTextField t;

    Play2()
    {
        JFrame j=new JFrame("MusicPlayer");
        j.setSize(300,300);
        j.setDefaultCloseOperation(EXIT_ON_CLOSE);
        b=new JButton("Play");
        b1=new JButton("Stop");
        JPanel p=new JPanel();
        t=new JTextField(20);
        p.add(t);
        p.add(b);
        p.add(b1);
        j.add(p);
        j.setVisible(true);


    }
    public void awt()
    {
    b.addActionListener(
            new ActionListener(){
                  public void actionPerformed(ActionEvent ae){
                try  
                    {  

            String fname=t.getText();
            File directory = new File(fname);

            boolean isDirectory = directory.isDirectory();

            if (isDirectory) 
             {
                    // It returns true if directory is a directory.
                System.out.println("the name you have entered is a directory  : "  +  directory);  
                    //It returns the absolutepath of a directory.
                    System.out.println("the path is "  +  directory.getAbsolutePath());
             }
            else
            {
                    // It returns false if directory is a file.
                System.out.println("the name you have entered is a file  : " + directory);
                    //It returns the absolute path of a file.
                    System.out.println("the path is "  + directory.getAbsolutePath());
            }
                String s=directory.getAbsolutePath();

                s=s.replace("\\","/") ;

                    FileInputStream fis=new FileInputStream(s);  
                    final Player playMp3=new Player(fis);  

                    playMp3.play(); 
        }
        catch(Exception e){
            System.out.println(e);}
        }//end actionPerformed
      }//end ActionListener
    );//end addActionListener()

    b1.addActionListener(
      new ActionListener(){
        public void actionPerformed(
                                  ActionEvent ae){
          //Terminate playback before EOF
                    try  
                    {  

            String fname=t.getText();
            File directory = new File(fname);

            boolean isDirectory = directory.isDirectory();

            if (isDirectory) 
             {
                    // It returns true if directory is a directory.
                System.out.println("the name you have entered is a directory  : "  +  directory);  
                    //It returns the absolutepath of a directory.
                    System.out.println("the path is "  +  directory.getAbsolutePath());
             }
            else
            {
                    // It returns false if directory is a file.
                System.out.println("the name you have entered is a file  : " + directory);
                    //It returns the absolute path of a file.
                    System.out.println("the path is "  + directory.getAbsolutePath());
            }
                String s=directory.getAbsolutePath();

                s=s.replace("\\","/") ;

                    FileInputStream fis=new FileInputStream(s);  
                    final Player playMp3=new Player(fis);  

                    playMp3.close(); 
        }
        catch(Exception e){
            System.out.println(e);}
        }//end actionPerformed
      }//end ActionListener
    );//end addActionListener()

    }


        public static void main(String[]args)  
        {  
        Play2 f=new Play2();
        f.awt();    
    }

}  
4

1 回答 1

0

您在这里所做的是使用播放按钮侦听器占用 EDT(事件调度线程)。

当您单击播放按钮时,一个 ActionEvent 将被发布到事件队列。如果您随后按下停止按钮,则会将另一个 ActionEvent 发布到 EventQueue。

EDT 将开始处理事件队列中的第一个事件(播放事件)。在这种情况下,您调用EDTplay()上 (mp3) 类的方法。Playerplay()方法不断循环,直到播放完整个 mp3。在这整个时间内,另一个事件(停止事件)将在事件队列中等待轮到它执行。所以当最后轮到stop事件执行时,mp3已经播放到最后了,stop命令比较多余。


主要问题:您不应该在 EDT 上执行冗长的任务。

解决办法:确保 play 方法在非 EDT 线程上执行,使用SwingWorker 类调用该Player.play()方法。

参考Swing UI 的 Event-Dispatch Thread Rules(在线文章)(您可能会感兴趣阅读此内容。尤其是“从不延迟 EDT ”部分中的信息,其中包含有关此特定问题的信息)

于 2013-01-15T15:15:38.323 回答