我想要的是将图像从一个JPanel拖放到另一个JPanel.我能够通过使用dnd库来实现.但是我坚持下去因为我不能从我放下它的面板(从放置目标)拖动图像.这意味着droptarget也需要充当dragSource.我是怎么做到的
解决方法
也许这有助于：
http://www.java2s.com/Code/Java/Swing-JFC/DragPictureDemo2.htm
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IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST * REVENUE,PROFIT OR DATA,OR FOR DIRECT,INDIRECT,SPECIAL,CONSEQUENTIAL,* INCIDENTAL OR PUNITIVE damAGES,HOWEVER CAUSED AND REGARDLESS OF THE THEORY * OF LIABILITY,ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH damAGES. * * You ackNowledge that this software is not designed,licensed or intended * for use in the design,construction,operation or maintenance of any * nuclear facility. */ /* * DragPictureDemo2.java is a 1.4 example that requires the following files: * Picture.java DTPicture.java PictureTransferHandler.java * TransferActionListener.java images/Maya.jpg images/Anya.jpg images/Laine.jpg * images/Cosmo.jpg images/Adele.jpg images/Alexi.jpg */ import java.awt.BorderLayout; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.GridLayout; import java.awt.Image; import java.awt.KeyboardFocusManager; import java.awt.datatransfer.DataFlavor; import java.awt.datatransfer.Transferable; import java.awt.datatransfer.UnsupportedFlavorException; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.FocusEvent; import java.awt.event.FocusListener; import java.awt.event.InputEvent; import java.awt.event.KeyEvent; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import java.awt.event.MouseMotionListener; import java.beans.PropertyChangeEvent; import java.beans.Propertychangelistener; import java.io.File; import java.io.IOException; import java.net.MalformedURLException; import javax.accessibility.Accessible; import javax.swing.Action; import javax.swing.ActionMap; import javax.swing.BorderFactory; import javax.swing.ImageIcon; import javax.swing.InputMap; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JPanel; import javax.swing.Keystroke; import javax.swing.TransferHandler; //A version of DragPictureDemo that creates an //Edit menu with cut/copy/paste actions. //This demo adds a class called TransferActionDemo //that transfers the cut/copy/paste menu action //to the currently focused component. public class DragPictureDemo2 extends JPanel { DTPicture pic1,pic2,pic3,pic4,pic5,pic6,pic7,pic8,pic9,pic10,pic11,pic12; static String mayaString = "Maya"; static String anyaString = "Anya"; static String lainestring = "Laine"; static String cosmoString = "Cosmo"; static String adeleString = "Adele"; static String alexiString = "Alexi"; PictureTransferHandler picHandler; public DragPictureDemo2() { super(new BorderLayout()); picHandler = new PictureTransferHandler(); //Since we are using keyboard accelerators,we don't //need the component to install its own input map //bindings. DTPicture.setInstallInputMapBindings(false); JPanel mugshots = new JPanel(new GridLayout(4,3)); pic1 = new DTPicture(createImageIcon("images/" + mayaString + ".jpg",mayaString).getimage()); pic1.setTransferHandler(picHandler); mugshots.add(pic1); pic2 = new DTPicture(createImageIcon("images/" + anyaString + ".jpg",anyaString).getimage()); pic2.setTransferHandler(picHandler); mugshots.add(pic2); pic3 = new DTPicture(createImageIcon("images/" + lainestring + ".jpg",lainestring).getimage()); pic3.setTransferHandler(picHandler); mugshots.add(pic3); pic4 = new DTPicture(createImageIcon("images/" + cosmoString + ".jpg",cosmoString).getimage()); pic4.setTransferHandler(picHandler); mugshots.add(pic4); pic5 = new DTPicture(createImageIcon("images/" + adeleString + ".jpg",adeleString).getimage()); pic5.setTransferHandler(picHandler); mugshots.add(pic5); pic6 = new DTPicture(createImageIcon("images/" + alexiString + ".jpg",alexiString).getimage()); pic6.setTransferHandler(picHandler); mugshots.add(pic6); //These six components with no pictures provide handy //drop targets. pic7 = new DTPicture(null); pic7.setTransferHandler(picHandler); mugshots.add(pic7); pic8 = new DTPicture(null); pic8.setTransferHandler(picHandler); mugshots.add(pic8); pic9 = new DTPicture(null); pic9.setTransferHandler(picHandler); mugshots.add(pic9); pic10 = new DTPicture(null); pic10.setTransferHandler(picHandler); mugshots.add(pic10); pic11 = new DTPicture(null); pic11.setTransferHandler(picHandler); mugshots.add(pic11); pic12 = new DTPicture(null); pic12.setTransferHandler(picHandler); mugshots.add(pic12); setPreferredSize(new Dimension(450,630)); add(mugshots,BorderLayout.CENTER); setBorder(BorderFactory.createEmptyBorder(20,20,20)); } //Create an Edit menu to support cut/copy/paste. public JMenuBar createMenuBar() { JMenuItem menuItem = null; JMenuBar menuBar = new JMenuBar(); JMenu mainMenu = new JMenu("Edit"); mainMenu.setMnemonic(KeyEvent.VK_E); TransferActionListener actionListener = new TransferActionListener(); menuItem = new JMenuItem("Cut"); menuItem.setActionCommand((String) TransferHandler.getCutAction() .getValue(Action.NAME)); menuItem.addActionListener(actionListener); menuItem.setAccelerator(Keystroke.getKeystroke(KeyEvent.VK_X,ActionEvent.CTRL_MASK)); menuItem.setMnemonic(KeyEvent.VK_T); mainMenu.add(menuItem); menuItem = new JMenuItem("copy"); menuItem.setActionCommand((String) TransferHandler.getcopyAction() .getValue(Action.NAME)); menuItem.addActionListener(actionListener); menuItem.setAccelerator(Keystroke.getKeystroke(KeyEvent.VK_C,ActionEvent.CTRL_MASK)); menuItem.setMnemonic(KeyEvent.VK_C); mainMenu.add(menuItem); menuItem = new JMenuItem("Paste"); menuItem.setActionCommand((String) TransferHandler.getPasteAction() .getValue(Action.NAME)); menuItem.addActionListener(actionListener); menuItem.setAccelerator(Keystroke.getKeystroke(KeyEvent.VK_V,ActionEvent.CTRL_MASK)); menuItem.setMnemonic(KeyEvent.VK_P); mainMenu.add(menuItem); menuBar.add(mainMenu); return menuBar; } /** Returns an ImageIcon,or null if the path was invalid. */ protected static ImageIcon createImageIcon(String path,String description) { try { File imageURL = new File(path); if (imageURL == null) { System.err.println("Resource not found: " + path); return null; } else { return new ImageIcon(imageURL.toURI().toURL(),description); } } catch( MalformedURLException e ) { e.printstacktrace(); } return null; } /** * Create the GUI and show it. For thread safety,this method should be * invoked from the event-dispatching thread. */ private static void createAndShowGUI() { //Make sure we have nice window decorations. JFrame.setDefaultLookAndFeelDecorated(true); //Create and set up the window. JFrame frame = new JFrame("DragPictureDemo2"); frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the menu bar and content pane. DragPictureDemo2 demo = new DragPictureDemo2(); frame.setJMenuBar(demo.createMenuBar()); demo.setopaque(true); //content panes must be opaque frame.setContentPane(demo); //display the window. frame.pack(); frame.setVisible(true); } public static void main(String[] args) { //Schedule a job for the event-dispatching thread: //creating and showing this application's GUI. javax.swing.SwingUtilities.invokelater(new Runnable() { public void run() { createAndShowGUI(); } }); } } /* * DTPicture.java is used by the 1.4 DragPictureDemo.java example. */ //A subclass of Picture that supports Data Transfer. class DTPicture extends Picture implements MouseMotionListener { private MouseEvent firstMouseEvent = null; private static boolean installInputMapBindings = true; public DTPicture(Image image) { super(image); addMouseMotionListener(this); //Add the cut/copy/paste key bindings to the input map. //Note that this step is redundant if you are installing //menu accelerators that cause these actions to be invoked. //DragPictureDemo does not use menu accelerators and,since //the default value of installInputMapBindings is true,//the bindings are installed. DragPictureDemo2 does use //menu accelerators and so calls setInstallInputMapBindings //with a value of false. Your program would do one or the //other,but not both. if (installInputMapBindings) { InputMap imap = this.getInputMap(); imap.put(Keystroke.getKeystroke("ctrl X"),TransferHandler .getCutAction().getValue(Action.NAME)); imap.put(Keystroke.getKeystroke("ctrl C"),TransferHandler .getcopyAction().getValue(Action.NAME)); imap.put(Keystroke.getKeystroke("ctrl V"),TransferHandler .getPasteAction().getValue(Action.NAME)); } //Add the cut/copy/paste actions to the action map. //This step is necessary because the menu's action listener //looks for these actions to fire. ActionMap map = this.getActionMap(); map.put(TransferHandler.getCutAction().getValue(Action.NAME),TransferHandler.getCutAction()); map.put(TransferHandler.getcopyAction().getValue(Action.NAME),TransferHandler.getcopyAction()); map.put(TransferHandler.getPasteAction().getValue(Action.NAME),TransferHandler.getPasteAction()); } public void setimage(Image image) { this.image = image; this.repaint(); } public void mousepressed(MouseEvent e) { //Don't bother to drag if there is no image. if (image == null) return; firstMouseEvent = e; e.consume(); } public void mouseDragged(MouseEvent e) { //Don't bother to drag if the component displays no image. if (image == null) return; if (firstMouseEvent != null) { e.consume(); //If they are holding down the control key,copY rather than MOVE int ctrlMask = InputEvent.CTRL_DOWN_MASK; int action = ((e.getModifiersEx() & ctrlMask) == ctrlMask) ? TransferHandler.copY : TransferHandler.MOVE; int dx = Math.abs(e.getX() - firstMouseEvent.getX()); int dy = Math.abs(e.getY() - firstMouseEvent.getY()); //Arbitrarily define a 5-pixel shift as the //official beginning of a drag. if (dx > 5 || dy > 5) { //This is a drag,not a click. JComponent c = (JComponent) e.getSource(); TransferHandler handler = c.getTransferHandler(); //Tell the transfer handler to initiate the drag. handler.exportAsDrag(c,firstMouseEvent,action); firstMouseEvent = null; } } } public void mouseReleased(MouseEvent e) { firstMouseEvent = null; } public void mouseMoved(MouseEvent e) { } //This method is necessary because DragPictureDemo and //DragPictureDemo2 both use this class and DragPictureDemo //needs to have the input map bindings installed for //cut/copy/paste. DragPictureDemo2 uses menu accelerators //and does not need to have the input map bindings installed. //Your program would use one approach or the other,but not //both. The default for installInputMapBindings is true. public static void setInstallInputMapBindings(boolean flag) { installInputMapBindings = flag; } public static boolean getInstallInputMapBindingds() { //for completeness return installInputMapBindings; } } /* * Picture.java is used by the 1.4 TrackFocusDemo.java and DragPictureDemo.java * examples. */ class Picture extends JComponent implements MouseListener,FocusListener,Accessible { Image image; public Picture(Image image) { this.image = image; setFocusable(true); addMouseListener(this); addFocusListener(this); } public void mouseClicked(MouseEvent e) { //Since the user clicked on us,let's get focus! requestFocusInWindow(); } public void mouseEntered(MouseEvent e) { } public void mouseExited(MouseEvent e) { } public void mousepressed(MouseEvent e) { } public void mouseReleased(MouseEvent e) { } public void focusGained(FocusEvent e) { //Draw the component with a red border //indicating that it has focus. this.repaint(); } public void focusLost(FocusEvent e) { //Draw the component with a black border //indicating that it doesn't have focus. this.repaint(); } protected void paintComponent(Graphics graphics) { Graphics g = graphics.create(); //Draw in our entire space,even if isOpaque is false. g.setColor(Color.WHITE); g.fillRect(0,image == null ? 125 : image.getWidth(this),image == null ? 125 : image.getHeight(this)); if (image != null) { //Draw image at its natural size of 125x125. g.drawImage(image,this); } //Add a border,red if picture currently has focus if (isFocusOwner()) { g.setColor(Color.RED); } else { g.setColor(Color.BLACK); } g.drawRect(0,image == null ? 125 : image.getHeight(this)); g.dispose(); } } /* * PictureTransferHandler.java is used by the 1.4 DragPictureDemo.java example. */ class PictureTransferHandler extends TransferHandler { DataFlavor pictureFlavor = DataFlavor.imageFlavor; DTPicture sourcePic; boolean shouldRemove; public boolean importData(JComponent c,Transferable t) { Image image; if (canImport(c,t.getTransferDataFlavors())) { DTPicture pic = (DTPicture) c; //Don't drop on myself. if (sourcePic == pic) { shouldRemove = false; return true; } try { image = (Image) t.getTransferData(pictureFlavor); //Set the component to the new picture. pic.setimage(image); return true; } catch (UnsupportedFlavorException ufe) { System.out.println("importData: unsupported data flavor"); } catch (IOException ioe) { System.out.println("importData: I/O exception"); } } return false; } protected Transferable createTransferable(JComponent c) { sourcePic = (DTPicture) c; shouldRemove = true; return new PictureTransferable(sourcePic); } public int getSourceActions(JComponent c) { return copY_OR_MOVE; } protected void exportDone(JComponent c,Transferable data,int action) { if (shouldRemove && (action == MOVE)) { sourcePic.setimage(null); } sourcePic = null; } public boolean canImport(JComponent c,DataFlavor[] flavors) { for (int i = 0; i < flavors.length; i++) { if (pictureFlavor.equals(flavors[i])) { return true; } } return false; } class PictureTransferable implements Transferable { private Image image; PictureTransferable(DTPicture pic) { image = pic.image; } public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException { if (!isDataFlavorSupported(flavor)) { throw new UnsupportedFlavorException(flavor); } return image; } public DataFlavor[] getTransferDataFlavors() { return new DataFlavor[] { pictureFlavor }; } public boolean isDataFlavorSupported(DataFlavor flavor) { return pictureFlavor.equals(flavor); } } } /* * TransferActionListener.java is used by the 1.4 DragPictureDemo.java example. */ /* * A class that tracks the focused component. This is necessary to delegate the * menu cut/copy/paste commands to the right component. An instance of this * class is listening and when the user fires one of these commands,it calls * the appropriate action on the currently focused component. */ class TransferActionListener implements ActionListener,Propertychangelistener { private JComponent focusOwner = null; public TransferActionListener() { KeyboardFocusManager manager = KeyboardFocusManager .getCurrentKeyboardFocusManager(); manager.addPropertychangelistener("permanentFocusOwner",this); } public void propertyChange(PropertyChangeEvent e) { Object o = e.getNewValue(); if (o instanceof JComponent) { focusOwner = (JComponent) o; } else { focusOwner = null; } } public void actionPerformed(ActionEvent e) { if (focusOwner == null) return; String action = (String) e.getActionCommand(); Action a = focusOwner.getActionMap().get(action); if (a != null) { a.actionPerformed(new ActionEvent(focusOwner,ActionEvent.ACTION_PERFORMED,null)); } } }
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