imageviewer.java

Java编程例子(全新)演示基础的Java 功能,例如类,对象的使用,过程的调用,.

/**
   @version 1.22 2004-05-21
   @author Cay Horstmann
*/

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

/**
   A program for viewing images.
*/
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;
}