urldroptargetdemo.java

《SWING HACKS》源码 作者: Joshua Marinacci,Chris Adamson 著 徐晔 译 出版: 2007年2月

import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.dnd.*;
import javax.swing.*;
import java.net.URL;

public class URLDropTargetDemo extends JPanel
    implements DropTargetListener {

    DropTarget dropTarget;
    JLabel dropHereLabel;
    JTextField statusField;
    static DataFlavor urlFlavor;
    static {
        try {
            urlFlavor =
                new DataFlavor ("application/x-java-url; class=java.net.URL");
        } catch (ClassNotFoundException cnfe) {
            cnfe.printStackTrace();
        }
    }

    public URLDropTargetDemo()  {
        super(new BorderLayout());
        dropHereLabel = new JLabel ("Drop here",
                                    SwingConstants.CENTER);
        dropHereLabel.setFont (getFont().deriveFont (Font.BOLD, 24.0f));
        add (dropHereLabel, BorderLayout.CENTER);
        // set up drop target stuff
        dropTarget = new DropTarget (dropHereLabel, this);
        statusField = new JTextField (30);
        statusField.setEditable(false);
        add (statusField, BorderLayout.SOUTH);
    }

    public static void main (String[] args) {
        JFrame frame = new JFrame ("URL DropTarget Demo");
        URLDropTargetDemo demoPanel = new URLDropTargetDemo();
        frame.getContentPane().add (demoPanel);
        frame.pack();
        frame.setVisible(true);
    }


    // drop target listener events

    public void dragEnter (DropTargetDragEvent dtde) {
        System.out.println ("dragEnter");
    }

    public void dragExit (DropTargetEvent dte) {
        System.out.println ("dragExit");
    }
   
    public void dragOver (DropTargetDragEvent dtde) {
        System.out.println ("dragOver");

    }

    public void drop (DropTargetDropEvent dtde) {
        System.out.println ("drop");
        dtde.acceptDrop (DnDConstants.ACTION_COPY_OR_MOVE);
        Transferable trans = dtde.getTransferable();
        dumpDataFlavors (trans);
        boolean gotData = false;
        // try for application/x-java-url flavor
        try {
            if (trans.isDataFlavorSupported (urlFlavor)) {
                URL url = (URL) trans.getTransferData (urlFlavor);
                // System.out.println ("got a " + o.getClass().getName());
                statusField.setText (url.toString());
                statusField.setCaretPosition (0);
                gotData = true;
            } else if (trans.isDataFlavorSupported (DataFlavor.stringFlavor)) {
                String s = 
                    (String) trans.getTransferData (DataFlavor.stringFlavor);
                statusField.setText (s);
                gotData = true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            System.out.println ("gotData is " + gotData);
            dtde.dropComplete (gotData);
        }
    }

    public void dropActionChanged (DropTargetDragEvent dtde) {
        System.out.println ("dropActionChanged");

    }

    private void dumpDataFlavors (Transferable trans) {
        System.out.println ("Flavors:");
        DataFlavor[] flavors = trans.getTransferDataFlavors();
        for (int i=0; i<flavors.length; i++) {
            System.out.println ("*** " + i + ": " + flavors[i]);
        }
    }

}