listtransferhandler.java

java tutorial.sun公司官方出品。java入门书籍。最新版

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 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
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 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */ 

package dnd;

/*
 * ListTransferHandler.java is used by the ListCutPaste example.
 */

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

class ListTransferHandler extends TransferHandler {

    /**
     * Perform the actual data import.
     */
    public boolean importData(TransferHandler.TransferSupport info) {
        String data = null;

        //If we can't handle the import, bail now.
        if (!canImport(info)) {
            return false;
        }

        JList list = (JList)info.getComponent();
        DefaultListModel model = (DefaultListModel)list.getModel();
        //Fetch the data -- bail if this fails
        try {
            data = (String)info.getTransferable().getTransferData(DataFlavor.stringFlavor);
        } catch (UnsupportedFlavorException ufe) {
            System.out.println("importData: unsupported data flavor");
            return false;
        } catch (IOException ioe) {
            System.out.println("importData: I/O exception");
            return false;
        }

        if (info.isDrop()) { //This is a drop
            JList.DropLocation dl = (JList.DropLocation)info.getDropLocation();
            int index = dl.getIndex();
            if (dl.isInsert()) {
                model.add(index, data);
                return true;
            } else {
                model.set(index, data);
                return true;
            }
        } else { //This is a paste
            int index = list.getSelectedIndex();
            // if there is a valid selection,
            // insert data after the selection
            if (index >= 0) {
                model.add(list.getSelectedIndex()+1, data);
            // else append to the end of the list
            } else {
                model.addElement(data);
            }
            return true;
        }
    }

    /**
     * Bundle up the data for export.
     */
    protected Transferable createTransferable(JComponent c) {
        JList list = (JList)c;
        int index = list.getSelectedIndex();
        String value = (String)list.getSelectedValue();
        return new StringSelection(value);
    }

    /**
     * The list handles both copy and move actions.
     */
    public int getSourceActions(JComponent c) {
        return COPY_OR_MOVE;
    }

    /** 
     * When the export is complete, remove the old list entry if the
     * action was a move.
     */
    protected void exportDone(JComponent c, Transferable data, int action) {
        if (action != MOVE) {
            return;
        }
        JList list = (JList)c;
        DefaultListModel model = (DefaultListModel)list.getModel();
        int index = list.getSelectedIndex();
        model.remove(index);
    }

    /**
     * We only support importing strings.
     */
    public boolean canImport(TransferHandler.TransferSupport support) {
        // we only import Strings
        if (!support.isDataFlavorSupported(DataFlavor.stringFlavor)) {
            return false;
        }
        return true;
    }
}