choosedropactiondemo.java

java tutorial.sun公司官方出品。java入门书籍。最新版

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 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
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 *   - 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.
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 *     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,
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */ 

package dnd;

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

public class ChooseDropActionDemo extends JFrame {
    
    DefaultListModel from = new DefaultListModel();
    DefaultListModel copy = new DefaultListModel();
    DefaultListModel move = new DefaultListModel();
    JList dragFrom;
    
    public ChooseDropActionDemo() {
        super("ChooseDropActionDemo");
        
        for (int i = 15; i >= 0; i--) {
            from.add(0, "Source item " + i);
        }

        for (int i = 2; i >= 0; i--) {
            copy.add(0, "Target item " + i);
            move.add(0, "Target item " + i);
        }

        JPanel p = new JPanel();
        p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));
        dragFrom = new JList(from);
        dragFrom.setTransferHandler(new FromTransferHandler());
        dragFrom.setPrototypeCellValue("List Item WWWWWW");
        dragFrom.setDragEnabled(true);
        dragFrom.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        JLabel label = new JLabel("Drag from here:");
        label.setAlignmentX(0f);
        p.add(label);
        JScrollPane sp = new JScrollPane(dragFrom);
        sp.setAlignmentX(0f);
        p.add(sp);
        add(p, BorderLayout.WEST);
        
        JList moveTo = new JList(move);
        moveTo.setTransferHandler(new ToTransferHandler(TransferHandler.COPY));
        moveTo.setDropMode(DropMode.INSERT);
        JList copyTo = new JList(copy);
        copyTo.setTransferHandler(new ToTransferHandler(TransferHandler.MOVE));
        copyTo.setDropMode(DropMode.INSERT);
        
        p = new JPanel();
        p.setLayout(new BoxLayout(p, BoxLayout.Y_AXIS));
        label = new JLabel("Drop to COPY to here:");;
        label.setAlignmentX(0f);
        p.add(label);
        sp = new JScrollPane(moveTo);
        sp.setAlignmentX(0f);
        p.add(sp);
        label = new JLabel("Drop to MOVE to here:");
        label.setAlignmentX(0f);
        p.add(label);
        sp = new JScrollPane(copyTo);
        sp.setAlignmentX(0f);
        p.add(sp);
        p.setBorder(BorderFactory.createEmptyBorder(0, 2, 0, 0));
        add(p, BorderLayout.CENTER);
        
        ((JPanel)getContentPane()).setBorder(BorderFactory.createEmptyBorder(2, 2, 2, 2));

        getContentPane().setPreferredSize(new Dimension(320, 315));
    }

     private static void createAndShowGUI() {
        //Create and set up the window.
        ChooseDropActionDemo test = new ChooseDropActionDemo();
        test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        //Display the window.
        test.pack();
        test.setVisible(true);
    }

     public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                //Turn off metal's use of bold fonts
	        UIManager.put("swing.boldMetal", Boolean.FALSE);
                createAndShowGUI();
            }
        });
    }
    
    class FromTransferHandler extends TransferHandler {
        public int getSourceActions(JComponent comp) {
            return COPY_OR_MOVE;
        }

        private int index = 0;

        public Transferable createTransferable(JComponent comp) {
            index = dragFrom.getSelectedIndex();
            if (index < 0 || index >= from.getSize()) {
                return null;
            }

            return new StringSelection((String)dragFrom.getSelectedValue());
        }
        
        public void exportDone(JComponent comp, Transferable trans, int action) {
            if (action != MOVE) {
                return;
            }

            from.removeElementAt(index);
        }
    }
    
    class ToTransferHandler extends TransferHandler {
        int action;
        
        public ToTransferHandler(int action) {
            this.action = action;
        }
        
        public boolean canImport(TransferHandler.TransferSupport support) {
            // for the demo, we'll only support drops (not clipboard paste)
            if (!support.isDrop()) {
                return false;
            }

            // we only import Strings
            if (!support.isDataFlavorSupported(DataFlavor.stringFlavor)) {
                return false;
            }

            boolean actionSupported = (action & support.getSourceDropActions()) == action;
            if (actionSupported) {
                support.setDropAction(action);
                return true;
            }

            return false;
        }

        public boolean importData(TransferHandler.TransferSupport support) {
            // if we can't handle the import, say so
            if (!canImport(support)) {
                return false;
            }

            // fetch the drop location
            JList.DropLocation dl = (JList.DropLocation)support.getDropLocation();

            int index = dl.getIndex();

            // fetch the data and bail if this fails
            String data;
            try {
                data = (String)support.getTransferable().getTransferData(DataFlavor.stringFlavor);
            } catch (UnsupportedFlavorException e) {
                return false;
            } catch (java.io.IOException e) {
                return false;
            }

            JList list = (JList)support.getComponent();
            DefaultListModel model = (DefaultListModel)list.getModel();
            model.insertElementAt(data, index);

            Rectangle rect = list.getCellBounds(index, index);
            list.scrollRectToVisible(rect);
            list.setSelectedIndex(index);
            list.requestFocusInWindow();

            return true;
        }  
    } 
}