java jtree 树行结构

package test;

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeNode;
import javax.swing.tree.TreePath;

public class MyTree extends JFrame implements TreeSelectionListener,ActionListener{
 private JTree jt;
 private DefaultTreeModel model;
 private DefaultTreeCellRenderer render;
 private TreeNode node;
 private JButton add_sib,add_child,delete,update;
 public MyTree(){
  model=new  DefaultTreeModel(getNode());
  jt=new JTree(model);
  jt.addTreeSelectionListener(this);
  JScrollPane jsc=new JScrollPane(jt);
  add_sib=new JButton("添加同级节点");
  add_child=new JButton("添加子节点");
  delete=new JButton("删除");
  update=new JButton("编辑");
  add_sib.addActionListener(this);
  add_child.addActionListener(this);
  delete.addActionListener(this);
  update.addActionListener(this);
  Box box=Box.createHorizontalBox();
  box.add(add_sib);
  box.add(add_child);
  box.add(delete);
  box.add(update);
  add(jsc,BorderLayout.CENTER);
  add(box,BorderLayout.SOUTH);
  this.pack();
  this.setResizable(true);
  this.setLocationRelativeTo(null);
  this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  this.setVisible(true);
 }
 public TreeNode getNode(){
  DefaultMutableTreeNode root=new DefaultMutableTreeNode("中国");
  DefaultMutableTreeNode province=new DefaultMutableTreeNode("广东");
  DefaultMutableTreeNode city=new DefaultMutableTreeNode("深圳");
  root.add(province);
  province.add(city);
  DefaultMutableTreeNode area=new DefaultMutableTreeNode("福田区");
  city.add(area);
  area=new DefaultMutableTreeNode("保安区");
  city.add(area);
  city=new DefaultMutableTreeNode("广州");
  province.add(city);
  province=new DefaultMutableTreeNode("江西");
  city=new DefaultMutableTreeNode("南昌");
  root.add(province);
  province.add(city);
  area=new DefaultMutableTreeNode("青山湖区");
  city.add(area);
  area=new DefaultMutableTreeNode("高新区");
  city.add(area);
  city=new DefaultMutableTreeNode("九江");
  province.add(city);
  return root;
 }
 public static void main(String[] args) {
  MyTree mt=new MyTree();
 }
 @Override
 public void valueChanged(TreeSelectionEvent e) {
//  System.out.println(jt.getLastSelectedPathComponent().toString());
  
 }
 @Override
 public void actionPerformed(ActionEvent e) {
  DefaultMutableTreeNode newNode = new DefaultMutableTreeNode("New");
  DefaultMutableTreeNode selectNode=(DefaultMutableTreeNode)jt.getLastSelectedPathComponent();
  if(e.getSource().equals(add_sib)){
   DefaultMutableTreeNode parent=(DefaultMutableTreeNode)selectNode.getParent();
   if(parent!=null){
    int index=parent.getIndex(selectNode);
    model.insertNodeInto(newNode, parent, index+1);
   }
  }else if(e.getSource().equals(add_child)){
   int count=selectNode.getChildCount();
   model.insertNodeInto(newNode, selectNode, count);
  }
  TreeNode[] nodes = model.getPathToRoot(newNode);
  TreePath path = new TreePath(nodes);
  jt.scrollPathToVisible(path);
 }

}