TreeTransferHandler.java 文件源码

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;
}