staticgenerator.java

learning java的源代码。书中每个实例都有相关的代码example。

//file: StaticGenerator.java
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.Random;
import javax.swing.*;

public class StaticGenerator extends JComponent implements Runnable {
  byte[] data;
  BufferedImage image;
  Random random;

  public void initialize(  ) {
    int w = getSize().width, h = getSize(  ).height;
    int length = ((w + 7) * h) / 8;
    data = new byte[length];
    DataBuffer db = new DataBufferByte(data, length);
    WritableRaster wr = Raster.createPackedRaster(db, w, h, 1, null);
    ColorModel cm = new IndexColorModel(1, 2,
        new byte[] { (byte)0, (byte)255 },
        new byte[] { (byte)0, (byte)255 },
        new byte[] { (byte)0, (byte)255 });
    image = new BufferedImage(cm, wr, false, null);
    random = new Random(  );
    new Thread(this).start(  );
  }

  public void run(  ) {
    while (true) {
      random.nextBytes(data);
      repaint(  );
      try { Thread.sleep(1000 / 24); }
      catch( InterruptedException e ) { /* die */ }
    }
  }

  public void paint(Graphics g) {
    if (image == null) initialize(  );
    g.drawImage(image, 0, 0, this);
  }

  public static void main(String[] args) {
    JFrame f = new JFrame("StaticGenerator");
    f.getContentPane().add(new StaticGenerator(  ));
    f.setSize(300, 300);
    f.setLocation(100, 100);
    f.addWindowListener(new WindowAdapter(  ) {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    f.setVisible(true);
  }
}