在JTree中拖放节点

之前没有做过，但是谷歌快速搜索在这里出现了同样的问题：http : //www.preranch.com/t/346509/GUI/java/JTree-drag-
drop-inside-one
它可以正常工作您可以查看的实现。

这是Craig Wood发布的相关代码：

import java.awt.*;import java.awt.datatransfer.*;import java.awt.dnd.*;import java.util.*;import java.util.List;import javax.swing.*;import javax.swing.tree.*;public class TreeDragAndDrop {    private JScrollPane getContent() {        JTree tree = new JTree();        tree.setDragEnabled(true);        tree.setDropMode(DropMode.ON_OR_INSERT);        tree.setTransferHandler(new TreeTransferHandler());        tree.getSelectionModel().setSelectionMode(     TreeSelectionModel.CONTIGUOUS_TREE_SELECTION);        expandTree(tree);        return new JScrollPane(tree);    }    private void expandTree(JTree tree) {        DefaultMutableTreeNode root = (DefaultMutableTreeNode)tree.getModel().getRoot();        Enumeration e = root.breadthFirstEnumeration();        while(e.hasMoreElements()) { DefaultMutableTreeNode node =     (DefaultMutableTreeNode)e.nextElement(); if(node.isLeaf()) continue; int row = tree.getRowForPath(new TreePath(node.getPath())); tree.expandRow(row);        }    }    public static void main(String[] args) {        Jframe f = new Jframe();        f.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);        f.add(new TreeDragAndDrop().getContent());        f.setSize(400,400);        f.setLocation(200,200);        f.setVisible(true);    }}class TreeTransferHandler extends TransferHandler {    DataFlavor nodesFlavor;    DataFlavor[] flavors = new DataFlavor[1];    DefaultMutableTreeNode[] nodesToRemove;    public TreeTransferHandler() {        try { String mimeType = DataFlavor.javaJVMLocalObjectMimeType +        ";class="" +     javax.swing.tree.DefaultMutableTreeNode[].class.getName() +        """; nodesFlavor = new DataFlavor(mimeType); flavors[0] = nodesFlavor;        } catch(ClassNotFoundException e) { System.out.println("ClassNotFound: " + e.getMessage());        }    }    public boolean canimport(TransferHandler.TransferSupport support) {        if(!support.isDrop()) { return false;        }        support.setShowDropLocation(true);        if(!support.isDataFlavorSupported(nodesFlavor)) { return false;        }        // Do not allow a drop on the drag source selections.        JTree.DropLocation dl =     (JTree.DropLocation)support.getDropLocation();        JTree tree = (JTree)support.getComponent();        int dropRow = tree.getRowForPath(dl.getPath());        int[] selRows = tree.getSelectionRows();        for(int i = 0; i < selRows.length; i++) { if(selRows[i] == dropRow) {     return false; }        }        // Do not allow MOVE-action drops if a non-leaf node is        // selected unless all of its children are also selected.        int action = support.getDropAction();        if(action == MOVE) { return haveCompleteNode(tree);        }        // Do not allow a non-leaf node to be copied to a level        // which is less than its source level.        TreePath dest = dl.getPath();        DefaultMutableTreeNode target = (DefaultMutableTreeNode)dest.getLastPathComponent();        TreePath path = tree.getPathForRow(selRows[0]);        DefaultMutableTreeNode firstNode = (DefaultMutableTreeNode)path.getLastPathComponent();        if(firstNode.getChildCount() > 0 &&    target.getLevel() < firstNode.getLevel()) { return false;        }        return true;    }    private boolean haveCompleteNode(JTree tree) {        int[] selRows = tree.getSelectionRows();        TreePath path = tree.getPathForRow(selRows[0]);        DefaultMutableTreeNode first = (DefaultMutableTreeNode)path.getLastPathComponent();        int childCount = first.getChildCount();        // first has children and no children are selected.        if(childCount > 0 && selRows.length == 1) return false;        // first may have children.        for(int i = 1; i < selRows.length; i++) { path = tree.getPathForRow(selRows[i]); DefaultMutableTreeNode next =     (DefaultMutableTreeNode)path.getLastPathComponent(); if(first.isNodeChild(next)) {     // Found a child of first.     if(childCount > selRows.length-1) {         // Not all children of first are selected.         return false;     } }        }        return true;    }    protected Transferable createTransferable(JComponent c) {        JTree tree = (JTree)c;        TreePath[] paths = tree.getSelectionPaths();        if(paths != null) { // Make up a node array of copies for transfer and // another for/of the nodes that will be removed in // exportDone after a successful drop. List<DefaultMutableTreeNode> copies =     new ArrayList<DefaultMutableTreeNode>(); List<DefaultMutableTreeNode> toRemove =     new ArrayList<DefaultMutableTreeNode>(); DefaultMutableTreeNode node =     (DefaultMutableTreeNode)paths[0].getLastPathComponent(); DefaultMutableTreeNode copy = copy(node); copies.add(copy); toRemove.add(node); for(int i = 1; i < paths.length; i++) {     DefaultMutableTreeNode next =         (DefaultMutableTreeNode)paths[i].getLastPathComponent();     // Do not allow higher level nodes to be added to list.     if(next.getLevel() < node.getLevel()) {         break;     } else if(next.getLevel() > node.getLevel()) {  // child node         copy.add(copy(next));         // node already contains child     } else {       // sibling         copies.add(copy(next));         toRemove.add(next);     } } DefaultMutableTreeNode[] nodes =     copies.toArray(new DefaultMutableTreeNode[copies.size()]); nodesToRemove =     toRemove.toArray(new DefaultMutableTreeNode[toRemove.size()]); return new NodesTransferable(nodes);        }        return null;    }        private DefaultMutableTreeNode copy(TreeNode node) {        return new DefaultMutableTreeNode(node);    }    protected void exportDone(JComponent source, Transferable data, int action) {        if((action & MOVE) == MOVE) { JTree tree = (JTree)source; DefaultTreeModel model = (DefaultTreeModel)tree.getModel(); // Remove nodes saved in nodesToRemove in createTransferable. for(int i = 0; i < nodesToRemove.length; i++) {     model.removeNodeFromParent(nodesToRemove[i]); }        }    }    public int getSourceActions(JComponent c) {        return COPY_OR_MOVE;    }    public boolean importData(TransferHandler.TransferSupport support) {        if(!canimport(support)) { return false;        }        // Extract transfer data.        DefaultMutableTreeNode[] nodes = null;        try { Transferable t = support.getTransferable(); nodes = (DefaultMutableTreeNode[])t.getTransferData(nodesFlavor);        } catch(UnsupportedFlavorException ufe) { System.out.println("UnsupportedFlavor: " + ufe.getMessage());        } catch(java.io.IOException ioe) { System.out.println("I/O error: " + ioe.getMessage());        }        // Get drop location info.        JTree.DropLocation dl =     (JTree.DropLocation)support.getDropLocation();        int childIndex = dl.getChildIndex();        TreePath dest = dl.getPath();        DefaultMutableTreeNode parent = (DefaultMutableTreeNode)dest.getLastPathComponent();        JTree tree = (JTree)support.getComponent();        DefaultTreeModel model = (DefaultTreeModel)tree.getModel();        // Configure for drop mode.        int index = childIndex;    // DropMode.INSERT        if(childIndex == -1) {     // DropMode.ON index = parent.getChildCount();        }        // Add data to model.        for(int i = 0; i < nodes.length; i++) { model.insertNodeInto(nodes[i], parent, index++);        }        return true;    }    public String toString() {        return getClass().getName();    }    public class NodesTransferable implements Transferable {        DefaultMutableTreeNode[] nodes;        public NodesTransferable(DefaultMutableTreeNode[] nodes) { this.nodes = nodes;         }        public Object getTransferData(DataFlavor flavor)throws UnsupportedFlavorException { if(!isDataFlavorSupported(flavor))     throw new UnsupportedFlavorException(flavor); return nodes;        }        public DataFlavor[] getTransferDataFlavors() { return flavors;        }        public boolean isDataFlavorSupported(DataFlavor flavor) { return nodesFlavor.equals(flavor);        }    }}