platform.java

金旭亮的java教案

/*
 * @(#)SimpleExample.java	1.26 01/12/03
 *
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

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

/**
 * An application that displays a JButton and several JRadioButtons.
 * The JRadioButtons determine the look and feel used by the application.
 */
public class PlatForm extends JPanel {
    static JFrame frame;

    static String metal= "Metal";
    static String metalClassName = "javax.swing.plaf.metal.MetalLookAndFeel";

    static String motif = "Motif";
    static String motifClassName = 
	    "com.sun.java.swing.plaf.motif.MotifLookAndFeel";

    static String windows = "Windows";
    static String windowsClassName = 
	    "com.sun.java.swing.plaf.windows.WindowsLookAndFeel";

    JRadioButton metalButton, motifButton, windowsButton;

    public PlatForm() {
	// Create the buttons.
	JButton button = new JButton("Hello, world");
        button.setMnemonic('h'); //for looks only; button does nada

	metalButton = new JRadioButton(metal);
        metalButton.setMnemonic('o'); 
	metalButton.setActionCommand(metalClassName);
        metalButton.setEnabled(isAvailableLookAndFeel(metalClassName));

	motifButton = new JRadioButton(motif);
        motifButton.setMnemonic('m'); 
	motifButton.setActionCommand(motifClassName);
        motifButton.setEnabled(isAvailableLookAndFeel(motifClassName));

	windowsButton = new JRadioButton(windows);
        windowsButton.setMnemonic('w'); 
	windowsButton.setActionCommand(windowsClassName);
        windowsButton.setEnabled(isAvailableLookAndFeel(windowsClassName));

	// Group the radio buttons.
	ButtonGroup group = new ButtonGroup();
	group.add(metalButton);
	group.add(motifButton);
	group.add(windowsButton);

        // Register a listener for the radio buttons.
	RadioListener myListener = new RadioListener();
	metalButton.addActionListener(myListener);
	motifButton.addActionListener(myListener);
	windowsButton.addActionListener(myListener);

	add(button);
	add(metalButton);
	add(motifButton);
	add(windowsButton);
    }


    protected boolean isAvailableLookAndFeel(String laf) {
         try { 
             Class lnfClass = Class.forName(laf);
             LookAndFeel newLAF = (LookAndFeel)(lnfClass.newInstance());
             return newLAF.isSupportedLookAndFeel();
         } catch(Exception e) { // If ANYTHING weird happens, return false
             return false;
         }
     }


    /** An ActionListener that listens to the radio buttons. */
    class RadioListener implements ActionListener {
	public void actionPerformed(ActionEvent e) {
	    String lnfName = e.getActionCommand();

            try {
		UIManager.setLookAndFeel(lnfName);
		SwingUtilities.updateComponentTreeUI(frame);
		frame.pack();
            } 
	    catch (Exception exc) {
		JRadioButton button = (JRadioButton)e.getSource();
		button.setEnabled(false);
		updateState();
                System.err.println("Could not load LookAndFeel: " + lnfName);
            }
	    
	}
    }

    public void updateState() {
	 String lnfName = UIManager.getLookAndFeel().getClass().getName();
	 if (lnfName.indexOf(metal) >= 0) {
	     metalButton.setSelected(true);
	 } else if (lnfName.indexOf(windows) >= 0) {
	     windowsButton.setSelected(true);
	 } else if (lnfName.indexOf(motif) >= 0) {
	     motifButton.setSelected(true);
	 } else {
	     System.err.println("SimpleExample is using an unknown L&F: " + lnfName);
	 }
    }

    public static void main(String s[]) {
	/* 
	   NOTE: By default, the look and feel will be set to the
	   Cross Platform Look and Feel (which is currently Metal).
	   The user may someday be able to override the default
	   via a system property. If you as the developer want to
	   be sure that a particular L&F is set, you can do so
	   by calling UIManager.setLookAndFeel(). For example, the
	   first code snippet below forcibly sets the UI to be the
	   System Look and Feel. The second code snippet forcibly
	   sets the look and feel to the Cross Platform L&F.

	   Snippet 1:
	      try {
	          UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
	      } catch (Exception exc) {
	          System.err.println("Error loading L&F: " + exc);
	      }

	   Snippet 2:
	      try {
	          UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
	      } catch (Exception exc) {
	          System.err.println("Error loading L&F: " + exc);
              }
	*/

	PlatForm panel = new PlatForm();
	
	frame = new JFrame("SimpleExample");
	frame.addWindowListener(new WindowAdapter() {
	    public void windowClosing(WindowEvent e) {System.exit(0);}
	});
	frame.getContentPane().add("Center", panel);
	frame.pack();
	frame.setLocation(300,300);
	frame.setVisible(true);
	
	panel.updateState();
    }
}