java制作简易电子琴

制作简易电子琴可以使用Java语言中的javax.sound.midi包和java.awt包。以下是一个简单的Java代码示例，演示如何使用这些包来制作简易电子琴：

import javax.sound.midi.*;
import java.awt.*;
import java.awt.event.*;

public class SimplePiano extends Frame implements ActionListener, Receiver {
    private static final int DEFAULT_CHANNEL = 0;
    private static final int DEFAULT_VELOCITY = 64;
    private static final int DEFAULT_DURATION = 100;

    private MidiDevice device;
    private Receiver receiver;
    private int channel;
    private int velocity;
    private int duration;

    public SimplePiano() throws MidiUnavailableException {
        setTitle("Simple Piano");
        setSize(300, 200);
        setResizable(false);
        setLayout(new GridLayout(0, 5));

        add(createButton("C"));
        add(createButton("D"));
        add(createButton("E"));
        add(createButton("F"));
        add(createButton("G"));
        add(createButton("A"));
        add(createButton("B"));
        add(createButton("C#"));
        add(createButton("D#"));
        add(createButton("F#"));
        add(createButton("G#"));
        add(createButton("A#"));

        device = MidiSystem.getDefaultMidiDevice();
        device.open();
        receiver = device.getReceiver();
        channel = DEFAULT_CHANNEL;
        velocity = DEFAULT_VELOCITY;
        duration = DEFAULT_DURATION;
    }

    private Button createButton(String label) {
        Button button = new Button(label);
        button.addActionListener(this);
        return button;
    }

    public void actionPerformed(ActionEvent e) {
        String noteName = e.getActionCommand();
        int noteNumber = getNoteNumber(noteName);
        if (noteNumber != -1) {
            sendNoteOn(noteNumber);
            try {
                Thread.sleep(duration);
            } catch (InterruptedException ex) {
            }
            sendNoteOff(noteNumber);
        }
    }

    public void send(MidiMessage message, long timeStamp) {
        ShortMessage shortMessage = (ShortMessage) message;
        int command = shortMessage.getCommand();
        int data1 = shortMessage.getData1();
        int data2 = shortMessage.getData2();
        if (command == ShortMessage.NOTE_ON) {
            System.out.println("Note on: " + data1);
        } else if (command == ShortMessage.NOTE_OFF) {
            System.out.println("Note off: " + data1);
        }
        receiver.send(message, timeStamp);
    }

    public void close() {
        device.close();
    }

    private int getNoteNumber(String noteName) {
        String[] noteNames = { "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B" };
        int[] noteNumbers = { 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71 };
        for (int i = 0; i < noteNames.length; i++) {
            if (noteName.equals(noteNames[i])) {
                return noteNumbers[i];
            }
        }
        return -1;
    }

    private void sendNoteOn(int noteNumber) {
        ShortMessage message = new ShortMessage();
        try {
            message.setMessage(ShortMessage.NOTE_ON, channel, noteNumber, velocity);
        } catch (InvalidMidiDataException e) {
        }
        receiver.send(message, -1);
    }

    private void sendNoteOff(int noteNumber) {
        ShortMessage message = new ShortMessage();
        try {
            message.setMessage(ShortMessage.NOTE_OFF, channel, noteNumber, velocity);
        } catch (InvalidMidiDataException e) {
        }
        receiver.send(message, -1);
    }

    public static void main(String[] args) {
        try {
            SimplePiano piano = new SimplePiano();
            piano.setVisible(true);
            piano.addWindowListener(new WindowAdapter() {
                public void windowClosing(WindowEvent e) {
                    piano.close();
                    System.exit(0);
                }
            });
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

这个程序创建了一个简单的GUI窗口，其中包含12个按钮，每个按钮代表一个音符。当用户按下一个按钮时，程序会向MIDI设备发送一个NOTE_ON消息，然后等待一段时间（即音符的持续时间），然后发送一个NOTE_OFF消息。这样就可以实现一个简单的电子琴。