树形框动态拖放效果，树形动态拖放,public class

树形框动态拖放效果，树形动态拖放,public class

public class DnDJTree extends JTree         implements DragSourceListener, DropTargetListener, DragGestureListener {        static DataFlavor localObjectFlavor;        static {            try {        localObjectFlavor =             new DataFlavor (DataFlavor.javaJVMLocalObjectMimeType);        } catch (ClassNotFoundException cnfe) { cnfe.printStackTrace(); }        }         static DataFlavor[] supportedFlavors = { localObjectFlavor };        DragSource dragSource;          DropTarget dropTarget;         TreeNode dropTargetNode = null;         TreeNode draggedNode = null;        public DnDJTree () {               super();                setCellRenderer (new DnDTreeCellRenderer());             setModel (new DefaultTreeModel(new DefaultMutableTreeNode("default")));                  dragSource = new DragSource();             DragGestureRecognizer dgr =        dragSource.createDefaultDragGestureRecognizer (this,                    DnDConstants.ACTION_MOVE,                                        this);            dropTarget = new DropTarget (this, this);        }        // DragGestureListener        public void dragGestureRecognized (DragGestureEvent dge) {            System.out.println ("dragGestureRecognized");            // find object at this x,y            Point clickPoint = dge.getDragOrigin();            TreePath path = getPathForLocation (clickPoint.x, clickPoint.y);            if (path == null) {        System.out.println ("not on a node");        return;            }            draggedNode = (TreeNode) path.getLastPathComponent();            Transferable trans = new RJLTransferable (draggedNode);            dragSource.startDrag (dge,Cursor.getDefaultCursor(),            trans, this);            }            // DragSourceListener events            public void dragDropEnd (DragSourceDropEvent dsde) {        System.out.println ("dragDropEnd()");        dropTargetNode = null;        draggedNode = null;        repaint();        }        public void dragEnter (DragSourceDragEvent dsde) {}        public void dragExit (DragSourceEvent dse) {}        public void dragOver (DragSourceDragEvent dsde) {}        public void dropActionChanged (DragSourceDragEvent dsde) {}        // DropTargetListener events        public void dragEnter (DropTargetDragEvent dtde) {              System.out.println ("dragEnter");             dtde.acceptDrag(DnDConstants.ACTION_COPY_OR_MOVE);            System.out.println ("accepted dragEnter");        }        public void dragExit (DropTargetEvent dte) {}        public void dragOver (DropTargetDragEvent dtde) {            // figure out which cell it's over, no drag to self            Point dragPoint = dtde.getLocation();            TreePath path = getPathForLocation (dragPoint.x, dragPoint.y);            if (path == null)            dropTargetNode = null;         else                   dropTargetNode = (TreeNode) path.getLastPathComponent();            repaint();        }        public void drop (DropTargetDropEvent dtde) {            System.out.println ("drop()!");            Point dropPoint = dtde.getLocation();            // int index = locationToIndex (dropPoint);            TreePath path = getPathForLocation (dropPoint.x, dropPoint.y);            System.out.println ("drop path is " + path);            boolean dropped = false;            try {        dtde.acceptDrop (DnDConstants.ACTION_MOVE);        System.out.println ("accepted");        Object droppedObject =            dtde.getTransferable().getTransferData(localObjectFlavor);         MutableTreeNode droppedNode = null;         if (droppedObject instanceof MutableTreeNode) {        // remove from old location        droppedNode = (MutableTreeNode) droppedObject;        ((DefaultTreeModel)getModel()).            removeNodeFromParent(droppedNode); }            else {        droppedNode = new DefaultMutableTreeNode (droppedObject);             }             // insert into spec'd path. if dropped into a parent             // make it last child of that parent             DefaultMutableTreeNode dropNode =            (DefaultMutableTreeNode) path.getLastPathComponent();            if (dropNode.isLeaf()) {         DefaultMutableTreeNode parent =        (DefaultMutableTreeNode) dropNode.getParent();             int index = parent.getIndex (dropNode);            ((DefaultTreeModel)getModel()).insertNodeInto (droppedNode,        parent, index); }     else {    ((DefaultTreeModel)getModel()).insertNodeInto         (droppedNode, dropNode,          dropNode.getChildCount());            }    dropped = true;    } catch (Exception e) {            e.printStackTrace();    }    dtde.dropComplete (dropped);    }    public void dropActionChanged (DropTargetDragEvent dtde) {}public static void main (String[] args) {    JTree tree = new DnDJTree(); DefaultMutableTreeNode root = newDefaultMutableTreeNode("People    DefaultMutableTreeNode set1 = new DefaultMutableTreeNode("Set 1");     DefaultMutableTreeNode set2 = new DefaultMutableTreeNode("Set 2");     DefaultMutableTreeNode set3 = new DefaultMutableTreeNode("Set 3");     set1.add (new DefaultMutableTreeNode ("Chris"));     set1.add (new DefaultMutableTreeNode ("Kelly"));     set1.add (new DefaultMutableTreeNode ("Keagan"));     set2.add (new DefaultMutableTreeNode ("Joshua"));     set2.add (new DefaultMutableTreeNode ("Kimi"));     set3.add (new DefaultMutableTreeNode ("Michael"));     set3.add (new DefaultMutableTreeNode ("Don"));     set3.add (new DefaultMutableTreeNode ("Daniel"));     root.add (set1);     root.add (set2);     set2.add (set3);     DefaultTreeModel mod = new DefaultTreeModel (root);     tree.setModel (mod);     // expand all        for (int i=0; i<tree.getRowCount(); i++)        tree.expandRow (i);    // show tree    JScrollPane scroller =        new JScrollPane (tree,         ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,         ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);    JFrame frame = new JFrame ("DnD JTree");    frame.getContentPane().add (scroller);    frame.pack();    frame.setVisible(true);}    class RJLTransferable implements Transferable {     Object object;     public RJLTransferable (Object o) {         object = o;     }     public Object getTransferData(DataFlavor df)         throws UnsupportedFlavorException, IOException {         if (isDataFlavorSupported (df))             return object;         else            throw new UnsupportedFlavorException(df);         }         public boolean isDataFlavorSupported (DataFlavor df) {             return (df.equals (localObjectFlavor));         }public DataFlavor[] getTransferDataFlavors () {            return supportedFlavors;        }       }The other helper inner class is where a lot of the "good stuff" happens. DnDJTreeCellRenderer, listed in the following code, has to be aware of what node is the potential drop targetthis is an instance variable set by dragOver( ) in the main classand if the node to be rendered is the drop target, it draws it differently:class DnDTreeCellRenderer    extends DefaultTreeCellRenderer {    boolean isTargetNode;    boolean isTargetNodeLeaf;    boolean isLastItem;    int BOTTOM_PAD = 30;    public DnDTreeCellRenderer() {        super();     }     public Component getTreeCellRendererComponent (JTree tree,                                Object value,                                 boolean isSelected,                                 boolean isExpanded,                                 boolean isLeaf,                                 int row,                                 boolean hasFocus) {        isTargetNode = (value == dropTargetNode);        isTargetNodeLeaf = (isTargetNode &&                            ((TreeNode)value).isLeaf());        // isLastItem = (index == list.getModel().getSize()-1);         boolean showSelected = isSelected &                (dropTargetNode == null);        return super.getTreeCellRendererComponent (tree, value,                                 isSelected, isExpanded,                                                     isLeaf, row, hasFocus);    }    public void paintComponent (Graphics g) {        super.paintComponent(g);        if (isTargetNode) {            g.setColor(Color.black);             if (isTargetNodeLeaf) {                g.drawLine (0, 0, getSize().width, 0);             } else {                g.drawRect (0, 0, getSize().width-1, getSize().height-1);             }         }     } }}//该片段来自于http://byrx.net