Javax.sound.midi研究在MacOS X上不起作用的代码

Question

我试图运行从javax.sound.midi包导入类的代码，但什么都不起作用。代码已成功编译并运行，但没有声音。我已经下载了soundbank for Java，并将其放在audio文件夹中，但它仍然不能工作。

Macbook Pro 2010年中

Mac OS X高山

2019-04-16 Java版本12.0.1

Java(TM) SE Runtime Environment (build 12.0.1+12)
Java HotSpot(TM) 64-Bit Server VM (build 12.0.1+12, mixed mode, sharing)

import javax.sound.midi.*;


public class MiniMiniMusicApp {

    public static void main(String[] args) {
        MiniMiniMusicApp mini = new MiniMiniMusicApp();
        mini.play();
    }

    public void play() {
        try {
            Sequencer player = MidiSystem.getSequencer();
            player.open();

            Sequence seq = new Sequence(Sequence.PPQ, 4);

            Track track = seq.createTrack();

            ShortMessage a = new ShortMessage();
            a.setMessage(128, 1, 44, 100);
            MidiEvent noteOn = new MidiEvent(a, 1);
            track.add(noteOn);

            ShortMessage b = new ShortMessage();
            b.setMessage(128, 1, 44, 100);
            MidiEvent noteOff = new MidiEvent(b, 16);
            track.add(noteOff);

            player.setSequence(seq);

            player.start();

        } catch (Exception ex) {ex.printStackTrace();}
    }
}

Answer 1

问题是您对a和b都使用了命令128。基于ShortMessage，命令128是音符关闭事件。

• 144 Event
• 128备注关闭Event
• 192用于更改默认仪器等的程序更改
• 176用于发送事件的控件更改
• 224间距折弯

例如，用a.setMessage(ShortMessage.NOTE_ON, 1, 44, 100);修改a.setMessage(128, 1, 44, 100);，你就会得到声音。

public static void play() {
    try {
        Sequencer player = MidiSystem.getSequencer();
        player.open();

        Sequence seq = new Sequence(Sequence.PPQ, 4);

        Track track = seq.createTrack();

        ShortMessage a = new ShortMessage();
        a.setMessage(ShortMessage.NOTE_ON, 1, 44, 100);
        MidiEvent noteOn = new MidiEvent(a, 5);
        track.add(noteOn);

        ShortMessage b = new ShortMessage();
        b.setMessage(ShortMessage.NOTE_OFF, 1, 44, 100);
        MidiEvent noteOff = new MidiEvent(b, 16);
        track.add(noteOff);

        player.setSequence(seq);

        player.start();

    } catch (Exception ex) {
        ex.printStackTrace();
    }
}