minimusicplayer3.java

HeadFirstCode系列图书里的源代码

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

  // this one plays random music with it, but only because there is a listener.

public class MiniMusicPlayer3 {

    static JFrame f = new JFrame("My First Music Video");
    static MyDrawPanel ml;

    public static void main(String[] args) {
           MiniMusicPlayer3 mini = new MiniMusicPlayer3();
           mini.go();
     }
   
 
     public  void setUpGui() {
       ml = new MyDrawPanel();
       f.setContentPane(ml);
       f.setBounds(30,30, 300,300);
       f.setVisible(true);
    }
 

    public void go() {
       setUpGui();

       try {

         // make (and open) a sequencer, make a sequence and track

         Sequencer sequencer = MidiSystem.getSequencer();         
         sequencer.open();
        
         sequencer.addControllerEventListener(ml, new int[] {127});
         Sequence seq = new Sequence(Sequence.PPQ, 4);
         Track track = seq.createTrack();     

         // now make two midi events (containing a midi message)

      int r = 0;
      for (int i = 0; i < 60; i+= 4) {

          r = (int) ((Math.random() * 50) + 1);
         
          track.add(makeEvent(144,1,r,100,i));
        
          track.add(makeEvent(176,1,127,0,i));
         
          track.add(makeEvent(128,1,r,100,i + 2));
       } // end loop
        
          // add the events to the track            
          // add the sequence to the sequencer, set timing, and start

          sequencer.setSequence(seq);
 
          sequencer.start();
          sequencer.setTempoInBPM(120);
      } catch (Exception ex) {ex.printStackTrace();}
  } // close go


   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;
       }



 class MyDrawPanel extends JPanel implements ControllerEventListener {
      
      // only if we got an event do we want to paint
      boolean msg = false;

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

      public void paintComponent(Graphics g) {
       if (msg) {
            
         Graphics2D g2 = (Graphics2D) g;

         int r = (int) (Math.random() * 250);
         int gr = (int) (Math.random() * 250);
         int b = (int) (Math.random() * 250);

         g.setColor(new Color(r,gr,b));

         int ht = (int) ((Math.random() * 120) + 10);
         int width = (int) ((Math.random() * 120) + 10);

         int x = (int) ((Math.random() * 40) + 10);
         int y = (int) ((Math.random() * 40) + 10);
         
         g.fillRect(x,y,ht, width);
         msg = false;

       } // close if
     } // close method
   }  // close inner class

} // close class