swing 图像浏览器

 //对于透明gif有效
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class SwingPic extends JFrame
{

    // Picture file name
    protected String filename = "", lastDir;
    protected ImageIcon image;
 Image im;
    int height, width, count = 0;
    JLabel labeledPic;
    JScrollPane scroller;
    Container content;

    // Constructor
    public SwingPic()
    {

        // Select local system look and feel
        try
        {
            UIManager.setLookAndFeel(UIManager.
                                     getCrossPlatformLookAndFeelClassName());
        }
        catch   (Exception e)
        {
        }

        // End program when window closes
        addWindowListener(new WindowAdapter()
                          {
                          public void windowClosing(WindowEvent e)
                          {
                          System.exit(0);}
                          }
        );

        setTitle("MJF Image Viewer");
        MenuBar mbar = new MenuBar();
        Menu m = new Menu("File");
        m.add(new MenuItem("Open"));
        m.add(new MenuItem("Exit"));
        mbar.add(m);
        setMenuBar(mbar);
        setSize(800, 600);

    }
    // Load image from file

    public void swingdraw()
    {
        if(count==1)               //load new image how to despote image before
        {                       // Create a label to hold the image as an icon
            labeledPic = new JLabel(image, JLabel.CENTER);
            labeledPic.setText(filename);

            // Create a scroller to hold the labeled image
            scroller = new JScrollPane(labeledPic);
            scroller.setPreferredSize(new Dimension(height, width));

            // Add the scroller to the frame's content layer 
            content = getContentPane();
            content.add(scroller);
            this.show();
            // Sets window's initial size
            //repaint();
        }
  else if(count>1)       //第二次就无法更新了，请大家看看如何实现可以更新。

  {  // image.setImage();
   labeledPic = new JLabel(image, JLabel.CENTER);
            labeledPic.setText(filename);
   
          System.out.println("new jlabel ");

            // Create a scroller to hold the labeled image
            scroller = new JScrollPane(labeledPic);
   scroller.setPreferredSize(new Dimension(height, width));

        //Let the scroll pane know to update itself
        //and its scroll bars.
           scroller.revalidate();
     // content = getContentPane();
           // content.add(scroller);
     scroller.repaint();
          //  this.show();

  }
    }

    public boolean action(Event evt, Object arg)
    {
        if(arg.equals("Open"))
        {
            FileDialog d =
                new FileDialog(this, "Open image file", FileDialog.LOAD);
            d.setFile("*.gif;*.jpg");
            d.setDirectory(lastDir);
            d.show();
            String f = d.getFile();
            lastDir = d.getDirectory();
            if(f != null)
            {                   //image=Toolkit.getDefaultToolkit().getImage(lastDir+f);
               // image = new ImageIcon(lastDir + f);
       im = Toolkit.getDefaultToolkit ().getImage (lastDir + f);
    if(im==null) return false;
    image=new ImageIcon(lastDir+f);
                height = image.getIconHeight();
                width = image.getIconWidth();
    System.out.println("new image icon"+height+" "+width);

            }
   System.out.println("new file"+lastDir+f);
            count++;
            swingdraw();
            //repaint();
        }
        else if(arg.equals("Exit"))
            System.exit(0);
        else
            return false;
        return true;
    }

    public static void main(String[]args)
    {
        SwingPic app = new SwingPic();
        app.setTitle("Swing Picture Demonstration");
        app.show();
    }
}

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