Java中的midi文件问题

Question

我正在阅读一本Java编程书，并且显示了以下示例：

// chapter 14

import java.awt.*;
import javax.swing.*;
import java.io.*;
import javax.sound.midi.*;
import java.util.*;
import java.awt.event.*;


public class BeatBox {  // implements MetaEventListener 

      JPanel mainPanel;
      ArrayList<JCheckBox> checkboxList;
      // int bpm = 120;
      Sequencer sequencer;
      Sequence sequence;
      Sequence mySequence = null;
      Track track;
      JFrame theFrame;

      String[] instrumentNames = {"Bass Drum", "Closed Hi-Hat", 
         "Open Hi-Hat","Acoustic Snare", "Crash Cymbal", "Hand Clap", 
         "High Tom", "Hi Bongo", "Maracas", "Whistle", "Low Conga", 
         "Cowbell", "Vibraslap", "Low-mid Tom", "High Agogo", 
         "Open Hi Conga"};
      int[] instruments = {35,42,46,38,49,39,50,60,70,72,64,56,58,47,67,63};


      public static void main (String[] args) {
        new BeatBox().buildGUI();
      }

      public void buildGUI() {
          theFrame = new JFrame("Cyber BeatBox");
          theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          BorderLayout layout = new BorderLayout();
          JPanel background = new JPanel(layout);
          background.setBorder(BorderFactory.createEmptyBorder(10,10,10,10));

          checkboxList = new ArrayList<JCheckBox>();
          Box buttonBox = new Box(BoxLayout.Y_AXIS);

          JButton start = new JButton("Start");
          start.addActionListener(new MyStartListener());
          buttonBox.add(start);


          JButton stop = new JButton("Stop");
          stop.addActionListener(new MyStopListener());
          buttonBox.add(stop);

          JButton upTempo = new JButton("Tempo Up");
          upTempo.addActionListener(new MyUpTempoListener());
          buttonBox.add(upTempo);

           JButton downTempo = new JButton("Tempo Down");
          downTempo.addActionListener(new MyDownTempoListener());
          buttonBox.add(downTempo);

          JButton saveIt = new JButton("Serialize It");  // new button
          saveIt.addActionListener(new MySendListener());
          buttonBox.add(saveIt);

          JButton restore = new JButton("Restore");     // new button
          restore.addActionListener(new MyReadInListener());
          buttonBox.add(restore);

          Box nameBox = new Box(BoxLayout.Y_AXIS);
          for (int i = 0; i < 16; i++) {
              nameBox.add(new Label(instrumentNames[i]));
          }

          background.add(BorderLayout.EAST, buttonBox);
          background.add(BorderLayout.WEST, nameBox);

          theFrame.getContentPane().add(background);

          GridLayout grid = new GridLayout(16,16);
          grid.setVgap(1);
          grid.setHgap(2);
          mainPanel = new JPanel(grid);
          background.add(BorderLayout.CENTER, mainPanel);


          for (int i = 0; i < 256; i++) {                    
                JCheckBox c = new JCheckBox();
                c.setSelected(false);
                checkboxList.add(c);
                mainPanel.add(c);            
          } // end loop

          setUpMidi();

          theFrame.setBounds(50,50,300,300);
          theFrame.pack();
          theFrame.setVisible(true);
        } // close method


     public void setUpMidi() {
       try {
        sequencer = MidiSystem.getSequencer();
        sequencer.open();
        // sequencer.addMetaEventListener(this);
        sequence = new Sequence(Sequence.PPQ,4);
        track = sequence.createTrack();
        sequencer.setTempoInBPM(120);

       } catch(Exception e) {e.printStackTrace();}
    } // close method
/*
     public class MyCheckBoxListener implements ItemListener {
        public void itemStateChanged(ItemEvent ev) {      
           // might add real-time removal or addition, probably not because of timing
        }
     } // close inner class
*/

     public void buildTrackAndStart() {
        // this will hold the instruments for each vertical column,
        // in other words, each tick (may have multiple instruments)
        int[] trackList = null;

        sequence.deleteTrack(track);
        track = sequence.createTrack();


      for (int i = 0; i < 16; i++) {
         trackList = new int[16];

         int key = instruments[i];

         for (int j = 0; j < 16; j++ ) {         
               JCheckBox jc = (JCheckBox) checkboxList.get(j + (16*i));

              if ( jc.isSelected()) {
                 trackList[j] = key;
              } else {
                 trackList[j] = 0;
              }       
          } // close inner

       makeTracks(trackList);
     } // close outer

     track.add(makeEvent(192,9,1,0,15)); // - so we always go to full 16 beats 



       try {

           sequencer.setSequence(sequence);  
           sequencer.setLoopCount(sequencer.LOOP_CONTINUOUSLY);                  
           sequencer.start();
           sequencer.setTempoInBPM(120);
       } catch(Exception e) {e.printStackTrace();}

      } // close method

//============================================================== inner class listeners           

      public class MyStartListener implements ActionListener {
        public void actionPerformed(ActionEvent a) {
             buildTrackAndStart();
         }
      }

    public class MyStopListener implements ActionListener {
       public void actionPerformed(ActionEvent a) {
           sequencer.stop();
       }
    }

    public class MyUpTempoListener implements ActionListener {
       public void actionPerformed(ActionEvent a) {
            float tempoFactor = sequencer.getTempoFactor();
            sequencer.setTempoFactor((float)(tempoFactor * 1.03));
       }
    }

    public class MyDownTempoListener implements ActionListener {
        public void actionPerformed(ActionEvent a) {
            float tempoFactor = sequencer.getTempoFactor();
            sequencer.setTempoFactor((float)(tempoFactor * .97));
        }
    }

    public class MySendListener implements ActionListener {    // new - save
       public void actionPerformed(ActionEvent a) {
          // make an arraylist of just the STATE of the checkboxes
         boolean[] checkboxState = new boolean[256];

         for (int i = 0; i < 256; i++) {
             JCheckBox check = (JCheckBox) checkboxList.get(i);
             if (check.isSelected()) {
                checkboxState[i] = true;
             }
          }

         try {
            FileOutputStream fileStream = new FileOutputStream(
                new File("Checkbox.ser"));
            ObjectOutputStream os = new ObjectOutputStream(fileStream);
            os.writeObject(checkboxState);
         } catch(Exception ex) {
             ex.printStackTrace();
         }

       } // close method
     } // close inner class



    public class MyReadInListener implements ActionListener {  // new - restore
        public void actionPerformed(ActionEvent a) {
          // read in the thing

          boolean[] checkboxState = null;
          try {
              FileInputStream fileIn = new FileInputStream(
                  new File("Checkbox.ser"));
              ObjectInputStream is = new ObjectInputStream(fileIn);
              checkboxState = (boolean[]) is.readObject();

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

              // now reset the sequence to be this
          for (int i = 0; i < 256; i++) {
             JCheckBox check = (JCheckBox) checkboxList.get(i);
             if (checkboxState[i]) {
                check.setSelected(true);
             } else {
                check.setSelected(false);
             }
         } 



        // now stop sequence and restart
        sequencer.stop(); 
        buildTrackAndStart();
      } // close method
  } // close inner class


//==============================================================       

     public void makeTracks(int[] list) {

         for (int i = 0; i < 16; i++) {
           int key = list[i];

           if (key != 0) {
               track.add(makeEvent(144,9,key, 100, i));
               track.add(makeEvent(128,9,key, 100, i + 1));
           }
         }
      }



     public  MidiEvent makeEvent(int comd, int chan, int one, int two, int tick) {
          MidiEvent event = null;
          try {
            ShortMessage a = new ShortMessage();
            a.setMessage(comd, chan, one, two);
            event = new MidiEvent(a, tick);

            }catch(Exception e) { }
          return event;
       }

/*
        public void meta(MetaMessage message) {
            if (message.getType() == 47) {
                sequencer.start();
                sequencer.setTempoInBPM(bpm);
            }
       }
*/


   } // close class

这是一台简单的beatboc机器，但我不知道为什么我的电脑上似乎坏了。 如果我尝试编译代码，则前3/4行会正常工作，但其他行会发出相同的声音....尤其是马拉卡斯，嗨邦戈，吹口哨...

对于其他在线用户来说，它似乎还可以正常工作，可能是什么问题？ 我还在/ lib / audio中安装了豪华声库，但没有任何改变。

Answer 1

我一直在研究同一本书（从Java入手），涵盖了Java 5.0。

如果您使用Java 7， 则已经实现了新的软件合成器 。 该代码不支持通用MIDI音库。

通过将遵循GM准则的音库加载到新的合成器实例中并将其链接到未连接的音序器，可以解决此问题。 这是一个合适的音库 。 但是网络上有一些不同的说法。

这是setupMidi（）方法中的代码：

public void setUpMidi() {
    try {

        sequencer = MidiSystem.getSequencer(false); // returns unconnected sequencer
        sequencer.open();

        synth = MidiSystem.getSynthesizer(); // return new synth 
        synth.open();

        soundbank = MidiSystem.getSoundbank(new File("32MbGMStereo.sf2"));
        synth.loadAllInstruments(soundbank); // load GM soundbank

        Receiver synthReceiver = synth.getReceiver();
        Transmitter seqTransmitter = sequencer.getTransmitter();
        seqTransmitter.setReceiver(synthReceiver); // connect sequencer to synth

        sequence = new Sequence(Sequence.PPQ,4);
        track = sequence.createTrack();
        sequencer.setTempoInBPM(120);

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

Answer 2

我已经尝试过您的代码。 似乎我的笔记本电脑（HP EliteBook）上的所有设备都可以正常工作。起初我遇到了一个错误，但是发现这是因为我需要以Admin身份运行Eclipse。 但是，我想是在您的书随附的论坛上找到了该解决方案。 参见： http : //forums.oreilly.com/topic/88039-windows-regcreatekeyex-returned-error-code-5/

我唯一注意到的是，如果循环正在运行，并且我检查了其他声音，则通常直到再次单击“开始”按钮时，它们才会播放这些声音。 但是，仅此而已。

编辑

我发现了一个类似的话题。 也许对您有用吗？ Mac OSX中的Java Midi损坏了吗？

编辑

为了刷新模式，在每次选择之后，我建议对您的代码进行更改，如下所示：

 public void buildTrack() {
         // this will hold the instruments for each vertical column,
         // in other words, each tick (may have multiple instruments)
         int[] trackList = null;

         sequence.deleteTrack(track);
         track = sequence.createTrack();


       for (int i = 0; i < 16; i++) {
          trackList = new int[16];

          int key = instruments[i];

          for (int j = 0; j < 16; j++ ) {         
                JCheckBox jc = (JCheckBox) checkboxList.get(j + (16*i));

               if ( jc.isSelected()) {
                  trackList[j] = key;
               } else {
                  trackList[j] = 0;
               }       
           } // close inner

        makeTracks(trackList);
      } // close outer

      track.add(makeEvent(192,9,1,0,15)); // - so we always go to full 16 beats 



        try {

            sequencer.setSequence(sequence);  

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

       } // close method

  public void buildTrackAndStart() {

    try {

        buildTrack();
        sequencer.setLoopCount(sequencer.LOOP_CONTINUOUSLY);                  
        sequencer.start();
        sequencer.setTempoInBPM(120);
    } catch(Exception e) {e.printStackTrace();}

   } // close method

然后您需要创建一个CheckBoxListener：

public class MyCheckboxListener implements ActionListener {
     public void actionPerformed(ActionEvent a) {
         buildTrack();
     }
 }

通过添加以下行，将其添加到您的复选框：

c.addActionListener(new MyCheckboxListener());

对于您的“ for”块，就在“ setupMidi（）”之前，如下所示：

for (int i = 0; i < 256; i++) {                    
             JCheckBox c = new JCheckBox();
             c.setSelected(false);
             c.addActionListener(new MyCheckboxListener());
             checkboxList.add(c);
             mainPanel.add(c);            
       } // end loop

那应该可以解决问题！