java学习笔记_MIDI_GUI

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

 class MyPanel_2 extends JPanel implements ControllerEventListener{
     boolean msg = false;

     public void paintComponent( Graphics g ) {
         if ( msg ) {
             g.fillRect(0, 0, this.getWidth(), this.getHeight());
             int red = (int) (Math.random() * 255);
             int green = (int) (Math.random() * 255);
             int blue = (int) (Math.random() * 255);
             Color randomColor = new Color(red, green, blue);
             g.setColor(randomColor);
             g.fillOval(70, 40, 100, 100);
             msg = false;
         }
     }

     public void controlChange(ShortMessage event) {
         msg = true;
         repaint();
     }
 }

 public class Midi{

     JFrame frame = new JFrame("My first Music Video");
     MyPanel_2 panel;    

     public void show_my_panel() {
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         panel = new MyPanel_2();
         frame.setContentPane(panel);
         frame.setBounds(30, 30, 300, 300);
         frame.setVisible(true);
     }

     public static MidiEvent makeEvent(int cmd, int chan, int one, int two, int tick) {
         MidiEvent event = null;
         try {
             ShortMessage a = new ShortMessage();
             a.setMessage(cmd, chan, one, two);
             event = new MidiEvent(a, tick);
         } catch (Exception e) {}
         return event;
     }

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

             int[] eventsIWant = {127};
             player.addControllerEventListener(panel, eventsIWant);

             Sequence seq = new Sequence(Sequence.PPQ, 4);//divisionType, resolution

             Track track = seq.createTrack();

             for (int i = 5; i < 61; i+= 4) {
                 track.add(makeEvent(144, 1, i, 100, i));
                 track.add(makeEvent(176, 1, 127, 0, i));
                 track.add(makeEvent(128, 1, i, 100, i + 2));
             }

             player.setSequence(seq);
             player.setTempoInBPM(220);
             player.start();
             while( player.isRunning() ) {
                 Thread.sleep(1000);
             }
             player.close();

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

     public static void main(String[] args) {
         Midi midi = new Midi();

         midi.show_my_panel();
         midi.play();
     }
 }