paneltest.java

java经典的源代码 我非常喜欢这个源代码 对于编程很有好处

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class panel extends JPanel {
  private int x1, y1, x2, y2;
  public panel(){
    addMouseListener(new MouseAdapter() {
      public void mousePressed( MouseEvent event ){
        x1 = event.getX();
        y1 = event.getY();
     }
  public void mouseReleased( MouseEvent event ){
    x2 = event.getX();
    y2 = event.getY();
    repaint();
  }
 });
 addMouseMotionListener( new MouseMotionAdapter() {
   public void mouseDragged( MouseEvent event ){
     x2 = event.getX();
     y2 = event.getY();
     repaint();
   }
 });
 } // end constructor
 public Dimension getPreferredSize(){
   return new Dimension( 300, 200 );
 }
 public void paintComponent( Graphics g ){
   super.paintComponent( g );
   g.drawOval( Math.min( x1, x2 ), Math.min( y1, y2 ),Math.abs( x1 - x2 ), Math.abs( y1 - y2 ) );
 }
}
public class panelTest extends JFrame {
  private panel myPanel;
  public panelTest(){
    super("JPanel test");
    myPanel = new panel();
    Container container = getContentPane();
    container.setLayout( new FlowLayout() );
    container.add( myPanel );
    addMouseMotionListener(new MouseMotionListener() {
      public void mouseDragged( MouseEvent event ){
        setTitle( "Dragging: x=" + event.getX() + "; y=" + event.getY() );
    }
   public void mouseMoved( MouseEvent event ){
     setTitle( "Moving: x=" + event.getX() + "; y=" + event.getY() );
   }
 } );
   setSize( 300, 200 );
   setVisible( true );
  }
 public static void main( String args[] ){
   panelTest app =new panelTest();
   app.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
 }
}