When we drag a Japanese named file from Windows Explorer onto our app, the characters in the filename are corrupted so that the app cannot open/access the file. (The problem appears to happen with any non-ascii character, i.e. >127.)

The problem occurs with the JDK 1.3 on Windows 98, NT 4.0, and Windows 2000.

The following code demonstrates the problem. Try to drag a file whose name contains multi-byte or non-ascii characters onto the JFrame window that the app opens. The window will display an error message and the garbage characters that were received in the drop.

import java.awt.*;
import java.awt.event.*;
import java.awt.dnd.*;
import java.awt.datatransfer.*;
import javax.swing.event.*;
import javax.swing.*;
import java.util.*;
import java.io.*;

public class DropLabel extends JLabel implements DropTargetListener
{
    public DropLabel(String s)
    {
        setText(s);
        new DropTarget (this, DnDConstants.ACTION_COPY, this, true);
        showDrop(false);
    }

    private void showDrop(boolean b)
    {
        setForeground (b?Color.white: Color.black);
    }

    public static void main(String[] args)
    {
        JFrame frame = new JFrame();
        frame.setTitle("DropLabel test");
        frame.getContentPane().add(new DropLabel("Drop here"));

        frame.addWindowListener( new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        frame.setSize(300,100);
        frame.setVisible(true);
    }

    /**
     * Configure to desired flavor of dropped data.
     */
    private DataFlavor getDesiredFlavor() {
        return DataFlavor.javaFileListFlavor;
    }

    /**
     * Check to make sure that the contains the expected object types.
     */
    private void checkDroppedData(Object data)
    {
        System.out.println( "Got data: "+data.getClass().getName());
        if (data instanceof AbstractList)
        {
            AbstractList files = (AbstractList)data;
            if (((File)files.get(0)).isFile())
              setText (((File)files.get(0)).toString());
            else
              setText("Error: not valid file: " +
((File)files.get(0)).toString());
        }
        else
        {
            System.out.println( "Error: wrong type of data dropped");
        }
    }

    private boolean isDragOk(DropTargetDragEvent e)
    {
        boolean canDrop = false;
        try
        {
            canDrop = e.isDataFlavorSupported(getDesiredFlavor());
}
        catch(Exception ex) {}

        if (canDrop)
            e.acceptDrag(DnDConstants.ACTION_COPY);
        else
            e.rejectDrag();
        showDrop (canDrop);
        return canDrop;
    }

    public void dragEnter(DropTargetDragEvent e)
    {
        isDragOk(e);
    }

    public void dragOver(DropTargetDragEvent e)
    {
        isDragOk(e);
    }

    public void dropActionChanged(DropTargetDragEvent e)
    {
        isDragOk(e);
    }

    public void dragExit(DropTargetEvent e)
    {
        showDrop (false);
    }

    public void drop(DropTargetDropEvent e)
    {
        try
        {
            e.acceptDrop(DnDConstants.ACTION_COPY);
            checkDroppedData(e.getTransferable().getTransferData(getDesiredFlavor()));
        }
        catch (Exception err) {}
        e.dropComplete(true);
        showDrop (false);
    }
}