如何做出一个复杂的JTree模型?

以下是一个关于JTree构建模型的例子，代码贴出来如下:

package  day18_JTree;

import  java.awt. * ;
import  java.awt.event. * ;
import  javax.swing. * ;
import  javax.swing.tree. * ;

class  TreeEditFrame  extends  JFrame  implements  ActionListener  {
     private   static   final   long  serialVersionUID  =   1L ;
     private  DefaultTreeModel model;
     private  JTree tree;
     private  JButton addSiblingButton;
     private  JButton addChildButton;
     private  JButton deleteButton;
    
     public  TreeEditFrame()  {
        setTitle( " TreeEditTest " );
        setSize( 300 ,  200 );
         this .pack();
         this .setSize( 500 , 200 );
        Toolkit tool  =  Toolkit.getDefaultToolkit();
         double  width  =  tool.getScreenSize().getWidth();
         double  height  =  tool.getScreenSize().getHeight();
         this .setLocation((( int )(width - this .getWidth())) / 2 ,( int )(height - this .getHeight()) / 2 );
         this .setVisible( true );
         this .setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        TreeNode root  =  makeSampleTree();
        model  =   new  DefaultTreeModel(root);
        tree  =   new  JTree(model);
        DefaultTreeCellRenderer renderer = new  DefaultTreeCellRenderer();
        renderer.setLeafIcon( new  ImageIcon( " 1.gif " ));
        renderer.setClosedIcon( new  ImageIcon( " 2.gif " ));
        renderer.setOpenIcon( new  ImageIcon( " 3.gif " ));
         // renderer.setBackgroundNonSelectionColor(Color.BLUE);
         // renderer.setBackgroundSelectionColor(Color.RED);
        renderer.setBorderSelectionColor(Color.RED);
        tree.setCellRenderer(renderer);
        Container contentPane  =  getContentPane();
        JScrollPane scrollPane  =   new  JScrollPane(tree);
        contentPane.add(scrollPane,  " Center " );
        JPanel panel  =   new  JPanel();
        addSiblingButton  =   new  JButton( " Add   Sibling " );
        addSiblingButton.addActionListener( this );
        panel.add(addSiblingButton);
        addChildButton  =   new  JButton( " Add   Child " );
        addChildButton.addActionListener( this );
        panel.add(addChildButton);
        deleteButton  =   new  JButton( " Delete " );
        deleteButton.addActionListener( this );
        panel.add(deleteButton);
        contentPane.add(panel,  " South " );
    }

     public  TreeNode makeSampleTree()  {
        DefaultMutableTreeNode root  =   new  DefaultMutableTreeNode( " World " );
        DefaultMutableTreeNode country  =   new  DefaultMutableTreeNode( " USA " );
        root.add(country);
        DefaultMutableTreeNode state  =   new  DefaultMutableTreeNode( " California " );
        country.add(state);
        DefaultMutableTreeNode city  =   new  DefaultMutableTreeNode( " San   Jose " );
        state.add(city);
        city  =   new  DefaultMutableTreeNode( " Cupertino " );
        state.add(city);
        state  =   new  DefaultMutableTreeNode( " Michigan " );
        country.add(state);
        city  =   new  DefaultMutableTreeNode( " Ann   Arbor " );
        state.add(city);
        country  =   new  DefaultMutableTreeNode( " Germany " );
        root.add(country);
        state  =   new  DefaultMutableTreeNode( " Schleswig-Holstein " );
        country.add(state);
        city  =   new  DefaultMutableTreeNode( " Kiel " );
        state.add(city);
         return  root;
    }
     public   void  actionPerformed(ActionEvent event)  {
        DefaultMutableTreeNode selectedNode  =  (DefaultMutableTreeNode) tree
        .getLastSelectedPathComponent();
         if  (selectedNode  ==   null )
             return ;
         if  (event.getSource().equals(deleteButton))  {
             if  (selectedNode.getParent()  !=   null )
                model.removeNodeFromParent(selectedNode);
             return ;
        }
        DefaultMutableTreeNode newNode  =   new  DefaultMutableTreeNode( " New " );
         if  (event.getSource().equals(addSiblingButton))  {
            DefaultMutableTreeNode parent  =  (DefaultMutableTreeNode) selectedNode
            .getParent();

             if  (parent  !=   null )  {
                 int  selectedIndex  =  parent.getIndex(selectedNode);
                model.insertNodeInto(newNode, parent, selectedIndex  +   1 );
            }
        }   else   if  (event.getSource().equals(addChildButton))  {
            model.insertNodeInto(newNode, selectedNode, selectedNode
                    .getChildCount());
        }
        TreeNode[] nodes  =  model.getPathToRoot(newNode);
        TreePath path  =   new  TreePath(nodes);
        tree.scrollPathToVisible(path);
    }
}  
public   class  TreeEditTest  {
     public   static   void  main(String[] args)  {
        JFrame frame  =   new  TreeEditFrame();
        frame.show();
    }
}

截图：