Swing小程序

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

 /**
 7.    A program for viewing images.
 8. */
  public class ImageViewer
 {
	 public static void main(String[] args)
    {
		 JFrame frame = new ImageViewerFrame();
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       frame.setVisible(true);
   }
 }

 /**
    A frame with a label to show an image.
 */
 class ImageViewerFrame extends JFrame
 {
    public ImageViewerFrame()
    {
       setTitle("ImageViewer");
       setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
      // use a label to display the images
       label = new JLabel();
       add(label);
       // set up the file chooser
       chooser = new JFileChooser();
       chooser.setCurrentDirectory(new File("."));
       // set up the menu bar
       JMenuBar menuBar = new JMenuBar();
       setJMenuBar(menuBar);

       JMenu menu = new JMenu("File");
       menuBar.add(menu);
     JMenuItem openItem = new JMenuItem("Open");
       menu.add(openItem);
       openItem.addActionListener(new
          ActionListener()
          {
             public void actionPerformed(ActionEvent event)
             {
                // show file chooser dialog
                int result = chooser.showOpenDialog(null);

                // if file selected, set it as icon of the label
                if (result == JFileChooser.APPROVE_OPTION)
                {
                   String name = chooser.getSelectedFile().getPath();
                   label.setIcon(new ImageIcon(name));
                }
             }
          });

       JMenuItem exitItem = new JMenuItem("Exit");
       menu.add(exitItem);
       exitItem.addActionListener(new
          ActionListener()
          {
             public void actionPerformed(ActionEvent event)
             {
                System.exit(0);
             }
          });
    }

    private JLabel label;
   private JFileChooser chooser;
  private static final int DEFAULT_WIDTH = 300;
    private static final int DEFAULT_HEIGHT = 400;
 }