click1.java

java语言规范

/*
 * Copyright 2002 Sun Microsystems, Inc. All  Rights Reserved.
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 * Redistribution and use in source and binary forms, with or 
 * without modification, are permitted provided that the following 
 * conditions are met:
 * 
 * -Redistributions of source code must retain the above copyright  
 *  notice, this list of conditions and the following disclaimer.
 * 
 * -Redistribution in binary form must reproduce the above copyright 
 *  notice, this list of conditions and the following disclaimer in 
 *  the documentation and/or other materials provided with the 
 *  distribution.
 *  
 * Neither the name of Sun Microsystems, Inc. or the names of 
 * contributors may be used to endorse or promote products derived 
 * from this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any 
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND 
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY 
 * EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY 
 * DAMAGES OR LIABILITIES  SUFFERED BY LICENSEE AS A RESULT OF OR 
 * RELATING TO USE, MODIFICATION OR DISTRIBUTION OF THE SOFTWARE OR 
 * ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE 
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 * SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER 
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF 
 * THE USE OF OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN 
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *  
 * You acknowledge that Software is not designed, licensed or 
 * intended for use in the design, construction, operation or 
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 */

import java.awt.*;
import java.awt.event.*;
import java.applet.*;


/** 
 * This version of the Click applet extends Click0 by adding a row
 * of "targets" along the top of the applet panel that highlight
 * when the mouse passes over them.  The listener that handles
 * enter/exit events is an instance of the private static class 
 * TargetListener.   A static class can't refer to fields or variables 
 * in enclosing scopes like an ordinary nested class (TargetListener
 * doesn't need to - it's self contained) however it's name is
 * scoped to the outer class.  For example, if TargetClass was 
 * public it could be used as Click1.TargetListener.  We've made
 * it private because it's not intended to be used outside of the
 * implementation of Click1.
 * 
 * Click1 has a bug: the puck no longer tracks the mouse correctly.
 * The fix is in Click2. 
 * 
 * This applet runs correctly in HotJava, it requires JDK 1.1.
 */

public class Click1 extends Applet
{
  Color puckColor = new Color(200, 0, 10);
  Box puck = new Box(puckColor);
  ColumnOfBoxes[] targets = new ColumnOfBoxes[8];

  private final static class TargetListener extends MouseAdapter
  {
    private Color newBackground;
    private Color oldBackground;

    TargetListener(Color newBackground) {
      this.newBackground = newBackground;
    }

    public void mouseEntered(MouseEvent e) {
      oldBackground = e.getComponent().getBackground();
      e.getComponent().setBackground(newBackground);
    }

    public void mouseExited(MouseEvent e) {
      e.getComponent().setBackground(oldBackground);
    }
  }

  public Click1()
  {
    MouseMotionListener movePuck = new MouseMotionAdapter() {
      public void mouseMoved(MouseEvent e)
      {
	int x = e.getX();
	int y = getSize().height - puck.getSize().height;
	puck.setLocation(x, y);
      }
    };

    /* Create a row of targets, i.e. columns of boxes, along
     * the top of the applet.  Each target column contains
     * between one and four boxes.
     */

    for(int i = 0; i < targets.length; i++) {
      int nBoxes = 1 + (int)(Math.random() * 3.0);
      float boxHue = (float)i / (float)targets.length;
      Color boxColor = Color.getHSBColor(boxHue, 0.5f, 0.85f);
      MouseListener targetListener = new TargetListener(boxColor.brighter());
      targets[i] = new ColumnOfBoxes(boxColor, nBoxes);
      targets[i].addMouseListener(targetListener);
      add(targets[i]);
    }

    add(puck);
    addMouseMotionListener(movePuck);
  }

  public static void main(String[] args)
  {
    WindowListener l = new WindowAdapter()
      {
	public void windowClosing(WindowEvent e) {System.exit(0);}
      };

    Frame f = new Frame("Click");
    f.addWindowListener(l); 
    f.add(new Click1());
    f.setSize(600, 400);
    f.show();
  }

  public String getAppletInfo() 
  { 
    return "Click1 by Hans Mueller. This version of the Click applet extends Click0 by adding a row of 'targets' along the top of the applet panel that highlight when the mouse passes over them.  The listener that handles enter/exit events is an instance of the private static class TargetListener.  A static class can't refer to fields or variables in enclosing scopes like an ordinary nested class (TargetListener doesn't need to - it's self contained) however it's name is scoped to the outer class.  For example, if TargetClass was public it could be used as Click1.TargetListener.  We've made it private because it's not intended to be used outside of the implementation of Click1.  Click1 has a bug: the puck no longer tracks the mouse correctly.  The fix is in Click2.  This applet requires JDK 1.1.";
  }
  
  public String[][] getParameterInfo() {
    return null;
  }   
  
}