Java Midi Sequencer - 使用播放头进行音符播放

Question

我目前实现了一项功能，允许用户播放他们演奏过的音符。

这是代码:

public void playNotes() throws InvalidMidiDataException,
        MidiUnavailableException {

    ArrayList<KeyPress> keyPressList = keyPressListCollection.getKeyPressList();
    double bpm = keyPressListCollection.getMetronome().getBpm();
    double millisPerTick = (60000.0 / (bpm * 16.0));
    double ticksPerMilli = 1 / millisPerTick;

    if (keyPressListCollection.isPlaying()) {
        sequencer.stop();
        sequencer.close();
    }

    sequencer = MidiSystem.getSequencer();
    sequencer.open();
    Sequence sequence = new Sequence(Sequence.PPQ, 16);
    Track track = sequence.createTrack();

    for (int i = 0; i < keyPressList.size(); i++) {
        KeyPress keyPress = keyPressList.get(i);

        ShortMessage noteOnMsg = new ShortMessage();
        noteOnMsg.setMessage(ShortMessage.NOTE_ON, 0, keyPress.getKeyNumber(), keyPress.getVelocity());

        ShortMessage noteOffMsg = new ShortMessage();
        noteOffMsg.setMessage(ShortMessage.NOTE_OFF, 0, keyPress.getKeyNumber(), 0);

        track.add(new MidiEvent(noteOnMsg, (long) (keyPress.getStartTime() * ticksPerMilli)));
        track.add(new MidiEvent(noteOffMsg, (long) (keyPress.getEndTime() * ticksPerMilli)));

    }

    keyPressListCollection.setPlaying(true);
    sequencer.setSequence(sequence);
    sequencer.setTempoInBPM((float) bpm);
    sequencer.start();

这工作正常，并在我的数组列表中播放音符。不过，我希望能够直观地向用户显示正在播放的音符或播放的位置。

问题是，如何为排序器处理的每个 MidiEvent 进行方法调用？

Answer 1

I want to be able to visually show the user .. or the position of which the playback is at.

使用 JProgressBar 。根据从 Sequencer 方法获取的值设置最大和当前位置 getMicrosecondLength() & getMicrosecondPosition() .