关于Drag and Drop的问题(请教各位高手)

Question

那肯定就是JDK的问题了，你搜遍了吗

Answer 1

a sample:import java.awt.*;
import java.io.*;
import java.util.*;
import java.awt.event.*;
import java.awt.dnd.*;
import java.awt.datatransfer.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;public class ListDemo extends JFrame
                      implements ListSelectionListener
{
    private DroppableList list;
    private JTextField fileName;    public ListDemo()
    {
        super("ListDemo");        //Create the list and put it in a scroll pane
        list = new DroppableList();
        DefaultListModel listModel = (DefaultListModel)list.getModel();
        list.setCellRenderer(new CustomCellRenderer());
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        list.setSelectedIndex(0);
        list.addListSelectionListener(this);
        JScrollPane listScrollPane = new JScrollPane(list);        String dirName = new String("\\");
        String filelist[] = new File(dirName).list();
        for (int i=0; i < filelist.length ; i++ )
        {
            String thisFileSt = dirName+filelist[i];
            File thisFile = new File(thisFileSt);
            if (thisFile.isDirectory())
                continue;
            try {
                listModel.addElement(makeNode(thisFile.getName(),
                                              thisFile.toURL().toString(),
                                              thisFile.getAbsolutePath()));
            } catch (java.net.MalformedURLException e){
            }
        }        fileName = new JTextField(50);
        String name = listModel.getElementAt(
                              list.getSelectedIndex()).toString();
        fileName.setText(name);        //Create a panel that uses FlowLayout (the default).
        JPanel buttonPane = new JPanel();
        buttonPane.add(fileName);        Container contentPane = getContentPane();
        contentPane.add(listScrollPane, BorderLayout.CENTER);
        contentPane.add(buttonPane, BorderLayout.NORTH);
    }    public void valueChanged(ListSelectionEvent e)
    {
        if (e.getValueIsAdjusting() == false)
        {
            fileName.setText("");
            if (list.getSelectedIndex() != -1)
            {
                String name = list.getSelectedValue().toString();
                fileName.setText(name);
            }
        }
    }    private static Hashtable makeNode(String name,
        String url, String strPath)
    {
        Hashtable hashtable = new Hashtable();
        hashtable.put("name", name);
        hashtable.put("url", url);
        hashtable.put("path", strPath);
        return hashtable;
    }    public class DroppableList extends JList
        implements DropTargetListener, DragSourceListener, DragGestureListener
    {
        DropTarget dropTarget = new DropTarget (this, this);
        DragSource dragSource = DragSource.getDefaultDragSource();        public DroppableList()
        {
          dragSource.createDefaultDragGestureRecognizer(
              this, DnDConstants.ACTION_COPY_OR_MOVE, this);
          setModel(new DefaultListModel());
        }        public void dragDropEnd(DragSourceDropEvent DragSourceDropEvent){}
        public void dragEnter(DragSourceDragEvent DragSourceDragEvent){}
        public void dragExit(DragSourceEvent DragSourceEvent){}
        public void dragOver(DragSourceDragEvent DragSourceDragEvent){}
        public void dropActionChanged(DragSourceDragEvent DragSourceDragEvent){}        public void dragEnter (DropTargetDragEvent dropTargetDragEvent)
        {
          dropTargetDragEvent.acceptDrag (DnDConstants.ACTION_COPY_OR_MOVE);
        }        public void dragExit (DropTargetEvent dropTargetEvent) {}
        public void dragOver (DropTargetDragEvent dropTargetDragEvent) {}
        public void dropActionChanged (DropTargetDragEvent dropTargetDragEvent){}        public synchronized void drop (DropTargetDropEvent dropTargetDropEvent)
        {
            try
            {
                Transferable tr = dropTargetDropEvent.getTransferable();
                if (tr.isDataFlavorSupported (DataFlavor.javaFileListFlavor))
                {
                    dropTargetDropEvent.acceptDrop (
                        DnDConstants.ACTION_COPY_OR_MOVE);
                    java.util.List fileList = (java.util.List)
                        tr.getTransferData(DataFlavor.javaFileListFlavor);
                    Iterator iterator = fileList.iterator();
                    while (iterator.hasNext())
                    {
                      File file = (File)iterator.next();
                      Hashtable hashtable = new Hashtable();
                      hashtable.put("name",file.getName());
                      hashtable.put("url",file.toURL().toString());
                      hashtable.put("path",file.getAbsolutePath());
                      ((DefaultListModel)getModel()).addElement(hashtable);
                    }
                    dropTargetDropEvent.getDropTargetContext().dropComplete(true);
              } else {
                System.err.println ("Rejected");
                dropTargetDropEvent.rejectDrop();
              }
            } catch (IOException io) {
                io.printStackTrace();
                dropTargetDropEvent.rejectDrop();
            } catch (UnsupportedFlavorException ufe) {
                ufe.printStackTrace();
                dropTargetDropEvent.rejectDrop();
            }
        }        public void dragGestureRecognized(DragGestureEvent dragGestureEvent)
        {
            if (getSelectedIndex() == -1)
                return;
            Object obj = getSelectedValue();
            if (obj == null) {
                // Nothing selected, nothing to drag
                System.out.println ("Nothing selected - beep");
                getToolkit().beep();
            } else {
                Hashtable table = (Hashtable)obj;
                FileSelection transferable =
                  new FileSelection(new File((String)table.get("path")));
                dragGestureEvent.startDrag(
                  DragSource.DefaultCopyDrop,
                  transferable,
                  this);
            }
        }
    }

Answer 2

public class CustomCellRenderer implements ListCellRenderer
    {
        DefaultListCellRenderer listCellRenderer =
          new DefaultListCellRenderer();
        public Component getListCellRendererComponent(
            JList list, Object value, int index,
            boolean selected, boolean hasFocus)
        {
            listCellRenderer.getListCellRendererComponent(
              list, value, index, selected, hasFocus);
            listCellRenderer.setText(getValueString(value));
            return listCellRenderer;
        }
        private String getValueString(Object value)
        {
            String returnString = "null";
            if (value != null) {
              if (value instanceof Hashtable) {
                Hashtable h = (Hashtable)value;
                String name = (String)h.get("name");
                String url = (String)h.get("url");
                returnString = name + " ==> " + url;
              } else {
                returnString = "X: " + value.toString();
              }
            }
            return returnString;
        }
    }    public class FileSelection extends Vector implements Transferable
    {
        final static int FILE = 0;
        final static int STRING = 1;
        final static int PLAIN = 2;
        DataFlavor flavors[] = {DataFlavor.javaFileListFlavor,
                                DataFlavor.stringFlavor,
                                DataFlavor.plainTextFlavor};
        public FileSelection(File file)
        {
            addElement(file);
        }
        /* Returns the array of flavors in which it can provide the data. */
        public synchronized DataFlavor[] getTransferDataFlavors() {
     return flavors;
        }
        /* Returns whether the requested flavor is supported by this object. */
        public boolean isDataFlavorSupported(DataFlavor flavor) {
            boolean b  = false;
            b |=flavor.equals(flavors[FILE]);
            b |= flavor.equals(flavors[STRING]);
            b |= flavor.equals(flavors[PLAIN]);
         return (b);
        }
        /**
         * If the data was requested in the "java.lang.String" flavor,
         * return the String representing the selection.
         */
        public synchronized Object getTransferData(DataFlavor flavor)
     throws UnsupportedFlavorException, IOException {
     if (flavor.equals(flavors[FILE])) {
         return this;
     } else if (flavor.equals(flavors[PLAIN])) {
         return new StringReader(((File)elementAt(0)).getAbsolutePath());
     } else if (flavor.equals(flavors[STRING])) {
         return((File)elementAt(0)).getAbsolutePath();
     } else {
         throw new UnsupportedFlavorException(flavor);
     }
        }
    }    public static void main(String s[])
    {
        JFrame frame = new ListDemo();
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        frame.pack();
        frame.setVisible(true);
    }
}

Answer 3

关于Dnd的大致看了一遍,好象是没有.

Answer 4

是不是有什么方法设置可以接收drop的？我以前做过一个拖放的程序，而且是applet，也是问题多多，在appletviewer里正常拿到ie里就不行了。后来整个重做了一遍就好了，奇怪！
另外，可以从别的程序（比如word）里拖文本到你的表格里试试，这样可以排除拖放源那边的问题。good luck

Answer 5

java 核心技术II 书上有例子。

Answer 6

applet好象Java本身就有Bug,我在java.sun.com上看到它的Bug report
java 核心技术II书上的我知道,但是不是那个问题的,呵呵,谢谢.

Answer 7

这是我的一个测试程序import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.dnd.*;
import java.awt.datatransfer.*;/**
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2002</p>
 * <p>Company: </p>
 * @author unascribed
 * @version 1.0
 */public class FrmTest1 extends JFrame {
    private JButton jButton1 = new JButton();
    String sTbl1 = "tbl1";
    String sTbl2 = "tbl2";
    String[] sCols1 = {"a1","b1","c1","d","e","f","g","h","i"};
    String[] sCols2 = {"a2","b2","c2"};
    private JTextField jTable1 = new JTextField(sTbl1);
    private JTextField jTable2 = new JTextField(sTbl2);
    public FrmTest1() {
        try {
            jbInit();
            //ウィンドウを中央に配置
            Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
            Dimension frameSize = this.getSize();
            if (frameSize.height > screenSize.height)
                frameSize.height = screenSize.height;
            if (frameSize.width > screenSize.width)
                frameSize.width = screenSize.width;
            this.setLocation((screenSize.width - frameSize.width) / 2, (screenSize.height - frameSize.height) / 2);
            this.setVisible(true);
            new DropTarget(jTable2, DnDConstants.ACTION_LINK,new TblDropListenre());
            DragSource dragSource = DragSource.getDefaultDragSource();
            dragSource.createDefaultDragGestureRecognizer(
                    jTable1, // component where drag originates
                    DnDConstants.ACTION_LINK, // actions
                    new TblGesture());
        }
        catch(Exception e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        FrmTest1 frmTest1 = new FrmTest1();
        frmTest1.show();
    }
    private void jbInit() throws Exception {
        this.setSize(400,300);
        jButton1.setBounds(new Rectangle(41, 29, 58, 16));
        jButton1.setText("jButton1");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(ActionEvent e) {
                jButton1_actionPerformed(e);
            }
        });
        this.getContentPane().setLayout(null);
        jTable1.setBounds(new Rectangle(37, 89, 136, 98));
        jTable2.setBounds(new Rectangle(199, 87, 146, 102));
        this.getContentPane().add(jButton1, null);
        this.getContentPane().add(jTable1, null);
        this.getContentPane().add(jTable2, null);
    }    void jButton1_actionPerformed(ActionEvent e) {    }
    class TblDragListener implements DragSourceListener{
        public void dragEnter(DragSourceDragEvent dsde){
            System.out.println("dragEnter(DragSourceDragEvent dsde)");
        }
        public void dragOver(DragSourceDragEvent dsde){
            System.out.println("dragOver(DragSourceDragEvent dsde)");
        }
        public void dragDropEnd(DragSourceDropEvent dsde){
            System.out.println("dragDropEnd(DragSourceDropEvent dsde)");
        }
        public void dropActionChanged(DragSourceDragEvent dsde){
            System.out.println("dropActionChanged(DragSourceDragEvent dsde)");
        }
        public void dragExit(DragSourceEvent dse){
            System.out.println("dragExit(DragSourceEvent dse)");
        }
    }
    class TblDropListenre implements DropTargetListener{
        public void dragEnter(DropTargetDragEvent dtde){
            System.out.println("dragEnter(DropTargetDragEvent dtde)");
        }
        public void dragOver(DropTargetDragEvent dtde){
            System.out.println("dragOver(DropTargetDragEvent dtde)");
        }
        public void dropActionChanged(DropTargetDragEvent dtde){
            System.out.println("dropActionChanged(DropTargetDragEvent dtde)");
        }
        public void dragExit(DropTargetEvent dte){
            System.out.println("dragExit(DropTargetEvent dte)");
        }
        public void drop(DropTargetDropEvent e){
            System.out.println("drop(DropTargetDropEvent e)");
        }
    }
    class TblGesture implements DragGestureListener{
        public void dragGestureRecognized(DragGestureEvent dge){
            System.out.println("dragGestureRecognized(DragGestureEvent dge)");
            int i = 1;
            DragData dd = new DragData(null,i);
            StrDataTransfer dataTransfer =  new StrDataTransfer(dd);
            if(dataTransfer == null){
                return;
            }
            dge.startDrag(DragSource.DefaultLinkDrop,dataTransfer,new TblDragListener());
        }
    }
    class StrDataTransfer implements Transferable{
        DragData data;
        DataFlavor flavor;
        public StrDataTransfer(JPanel tbl,int col){
            this.data = new DragData(tbl,col);
            try{
                flavor = new DataFlavor(Class.forName("FrmTest1$DragData"),"DragData");
            }catch(Exception e){
                e.printStackTrace();
            }
        }
        public StrDataTransfer(DragData df){
            this.data = df;
            try{
                flavor = new DataFlavor(Class.forName("FrmTest1$DragData"),"DragData");
            }catch(Exception e){
                e.printStackTrace();
            }
        }
        public Object getTransferData(DataFlavor flavor) {
            if(isDataFlavorSupported(flavor))
                return data;
            return null;
        }
        public DataFlavor[] getTransferDataFlavors(){
            DataFlavor[] df = {flavor};
            return df;
        }
        public boolean isDataFlavorSupported(DataFlavor flavor1){
            if(flavor1.equals(flavor))
                return true;
            return false;
        }
    }
    class DragData{
        private JPanel table;
        private int iCol;
        public DragData(JPanel tbl,int iCol){
            this.table = tbl;
            this.iCol = iCol;
        }
        public JPanel getTable(){
            return table;
        }
        public int getCol(){
            return iCol;
        }
    }
}