imageviewer.java

Java2核心技术卷一 配套源码,看了还不错

/**
 * @version 1.10 10 Mar 1997
 * @author Cay Horstmann
 */

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

public class ImageViewer extends JFrame
   implements ActionListener
{  public ImageViewer()
   {  setTitle("ImageViewer");
      setSize(300, 400);

      JMenuBar mbar = new JMenuBar();
      JMenu m = new JMenu("File");
      openItem = new JMenuItem("Open");
      openItem.addActionListener(this);
      m.add(openItem);
      exitItem = new JMenuItem("Exit");
      exitItem.addActionListener(this);
      m.add(exitItem);
      mbar.add(m);
      setJMenuBar(mbar);

      label = new JLabel();
      Container contentPane = getContentPane();
      contentPane.add(label, "Center");
   }

   public void actionPerformed(ActionEvent evt)
   {  Object source = evt.getSource();
      if (source == openItem)
      {  JFileChooser chooser = new JFileChooser();
         chooser.setCurrentDirectory(new File("."));

         chooser.setFileFilter(new
            javax.swing.filechooser.FileFilter()
            {  public boolean accept(File f)
               {  return f.getName().toLowerCase()
                     .endsWith(".gif")
                     || f.isDirectory();
               }
               public String getDescription()
               {  return "GIF Images";
               }
            });

         int r = chooser.showOpenDialog(this);
         if(r == JFileChooser.APPROVE_OPTION)
         {  String name
               = chooser.getSelectedFile().getName();
            label.setIcon(new ImageIcon(name));
         }
      }
      else if (source == exitItem) System.exit(0);
   }

   public static void main(String[] args)
   {  JFrame frame = new ImageViewer();
      frame.show();
   }

   private JLabel label;
   private JMenuItem openItem;
   private JMenuItem exitItem;
}