swingapplication.java

这是一个用java编写的关于GUI应用编程的简单的样例

package chap13.demo;
/*
 * SwingApplication.java is a 1.4 example that requires
 * no other files.
 */
import javax.swing.*;          
import java.awt.*;
import java.awt.event.*;

public class SwingApplication extends JFrame implements ActionListener {

    private static String labelPrefix = "Number of button clicks: ";
    private int numClicks = 0;
    final JLabel label = new JLabel(labelPrefix + "0    ");

    //Specify the look and feel to use.  Valid values:
    //null (use the default), "Metal", "System", "Motif", "GTK+"
    UIManager.LookAndFeelInfo[] feel=UIManager.getInstalledLookAndFeels(); 

    static String  lookAndFeel = null;


    public SwingApplication(String title) throws HeadlessException {
        super(title);
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Component contents = this.createComponents();
        this.getContentPane().add(contents, BorderLayout.CENTER);

        //Display the window.
        this.pack();
        this.setVisible(true);
    }

    private  Component createComponents() {
        JButton button = new JButton("I'm a Swing button!");
        button.setMnemonic(KeyEvent.VK_I);
        button.addActionListener(this);
        label.setLabelFor(button);

        /*
         * An easy way to put space between a top-level container
         * and its contents is to put the contents in a JPanel
         * that has an "empty" border.
         */
        JPanel pane = new JPanel(new GridLayout(0, 1));
        pane.add(button);
        pane.add(label);
        pane.setBorder(BorderFactory.createEmptyBorder(
                                        30, //top
                                        30, //left
                                        10, //bottom
                                        30) //right
                                        );

        return pane;
    }

    public void actionPerformed(ActionEvent e) {
        numClicks++;
        label.setText(labelPrefix + numClicks);
        lookAndFeel=feel[numClicks%feel.length].getClassName();
        System.out.println(lookAndFeel);
        initLookAndFeel();
    }

    private  void initLookAndFeel() {

            try {
                UIManager.setLookAndFeel(lookAndFeel);
                SwingUtilities.updateComponentTreeUI(this);
                this.pack();
                this.setVisible(true);

            } catch (ClassNotFoundException e) {
                System.err.println("Couldn't find class for specified look and feel:"
                                   + lookAndFeel);
                System.err.println("Did you include the L&F library in the class path?");
                System.err.println("Using the default look and feel.");
            } catch (UnsupportedLookAndFeelException e) {
                System.err.println("Can't use the specified look and feel ("
                                   + lookAndFeel
                                   + ") on this platform.");
                System.err.println("Using the default look and feel.");
            } catch (Exception e) {
                System.err.println("Couldn't get specified look and feel ("
                                   + lookAndFeel
                                   + "), for some reason.");
                System.err.println("Using the default look and feel.");
                e.printStackTrace();
            }
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                 SwingApplication app=new SwingApplication("SwingApplication");
            }
        });
    }
}