java - 如何调用我的音乐类并在 while 循环内播放音乐，该循环在调用音乐类的行下执行我的行？

Question

我有两个类，我想知道如何调用我的音乐类(MP3 class2)以使歌曲在第一类的 while 循环中播放。我的问题是当我使用 MP3.main(args); 时在第一类中，第一类中的 while 循环不执行 MP3.main(args); 行以下的内容。因此，不会显示文本“输入命令”。我想我需要重新创建我的 MP3 类并传递参数(如果这是正确使用术语的话)。抱歉我对java还是个新手。

请注意，我已从第一类中删除了许多代码，因为它是用于项目的。

如果有人问我为什么不删除第一类并将文本移至第二类，长话短说，这不是一个选择。

**CLASS 1 ** 尝试播放第二类中的音乐，但程序未执行 MP3.main(args); 行以下的内容在我的 while 循环中。

public class ClassTest {
    public static void main(String[] args) {
        // create the loop
        while (true) {
            MP3.main(args);
            System.out.println("Enter a command: ");
        }
    }
} 

2 级 MP3 级

import javazoom.jl.player.Player;

import java.io.BufferedInputStream;
import java.io.FileInputStream;


class MP3 {
    private static String filename = null;

    // constructor that takes the name of an MP3 file
    public MP3(String filename) {
        this.filename = filename;
    }

    // play the MP3 file to the sound card
    public static void play() {
        try {
            FileInputStream fis     = new FileInputStream(filename);
            BufferedInputStream bis = new BufferedInputStream(fis);
            Player player = new Player(bis);
            player.play();
        }
        catch (Exception e) {
            System.out.println("Problem playing file " + filename);
            System.out.println(e);
        }
    }


    // test client
    public static void main(String[] args) {
        String filename = ("Growth.mp3");
        MP3 mp3 = new MP3(filename);
        mp3.play();

        try {
            FileInputStream fis     = new FileInputStream(filename);
            BufferedInputStream bis = new BufferedInputStream(fis);
            Player player = new Player(bis);
            player.play();
        }
        catch (Exception e) {
            System.out.println("Problem playing file " + filename);
            System.out.println(e);
        }
    }

}

Answer 1

查看 play() 方法可以发现这是一个阻塞操作。您可以在单独的线程中调用该方法，这样您就可以测试玩家何时完成并重新调用 play 方法，如下所示:

MP3.java

import javazoom.jl.player.Player;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MP3 {

    private final String filename;

    private ExecutorService executorService;
    private Player player;

    public MP3(String filename) {
        this.filename = filename;
    }

    public void play() {
        try {
            FileInputStream fis = new FileInputStream(filename);
            BufferedInputStream bis = new BufferedInputStream(fis);
            player = new Player(bis);
            player.play();
        } catch (Exception e) {
            System.out.println("Problem playing file " + filename);
            e.printStackTrace();
        }
    }

    public void playAsync() {
        if (executorService == null) {
            executorService = Executors.newSingleThreadExecutor();
            executorService.submit(this::play);
        }
    }

    public void playForever() {
        while (true) {
            sleep();
            if (player == null || player.isComplete()) {
                System.out.println("Still playing: " + filename);
                stopAsync();
                playAsync();
            }
        }
    }

    public void stopAsync() {
        if (player != null) {
            player.close();
            player = null;
        }
        if (executorService != null) {
            executorService.shutdown();
            executorService = null;
        }
    }

    private void sleep() {
        try {
            Thread.sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

DemoApplication.java

public class DemoApplication {

    public static void main(String[] args) {
        String filename = ("Growth.mp3");
        MP3 mp3 = new MP3(filename);
        mp3.playForever();
    }
}