Question

我有这个简单的程序，它只使用MIDI播放一个音符。问题是，即使它播放了音符，程序仍在继续，但我不知道为什么。有什么帮助吗？

    Sequencer sequencer = MidiSystem.getSequencer();
    sequencer.open();
    Sequence sequence = new Sequence(Sequence.PPQ, 1);
    Track track = sequence.createTrack();

    ShortMessage noteOnMsg = new ShortMessage();
    noteOnMsg.setMessage(ShortMessage.NOTE_ON, 0, 60, 100);
    ShortMessage noteOffMsg = new ShortMessage();
    noteOffMsg.setMessage(ShortMessage.NOTE_OFF, 0, 60, 100);

    track.add(new MidiEvent(noteOnMsg, 0));
    track.add(new MidiEvent(noteOffMsg, 120));
    sequencer.setSequence(sequence);

    sequencer.start();
    Thread.sleep(5000);
    sequencer.stop();

Answer 1

需要关闭Sequencer。一种选择是只将sequencer.close()添加到代码的末尾，但由于Sequencer实现了AutoCloseable，更好的方法是将它放在try-with-resources子句中：

try (Sequencer sequencer = MidiSystem.getSequencer()) {
    sequencer.open();
    Sequence sequence = new Sequence(Sequence.PPQ, 1);
    Track track = sequence.createTrack();

    ShortMessage noteOnMsg = new ShortMessage();
    noteOnMsg.setMessage(ShortMessage.NOTE_ON, 0, 60, 100);
    ShortMessage noteOffMsg = new ShortMessage();
    noteOffMsg.setMessage(ShortMessage.NOTE_OFF, 0, 60, 100);

    track.add(new MidiEvent(noteOnMsg, 0));
    track.add(new MidiEvent(noteOffMsg, 120));
    sequencer.setSequence(sequence);

    sequencer.start();
    Thread.sleep(5000);
    sequencer.stop();
}

Answer 2

您需要使用

 if (sequencer != null && sequencer.isOpen()) {
  sequencer.stop();
  sequencer.setMicrosecondPosition(0);
}

我希望这对你有所帮助。

为什么我的MIDI程序没有完成/关闭？

2 个答案: