Java树形菜单的创建

import java.awt.*; import javax.swing.*; import javax.swing.tree.*; import javax.swing.event.*; public class Tree extends JFrame implements TreeSelectionListener {  private JLabel label;   public Tree()  {   super("树形菜单"); setSize(400,400);   Container container = getContentPane();    //创建根节点和子节点   DefaultMutableTreeNode root = new DefaultMutableTreeNode("文本编辑器");   DefaultMutableTreeNode node1 = new DefaultMutableTreeNode("文件");   DefaultMutableTreeNode node2 = new DefaultMutableTreeNode("编辑");   //利用根节点创建TreeModel   DefaultTreeModel treeModel = new DefaultTreeModel(root);   //插入子节点node1,node2   treeModel.insertNodeInto(node1,root,root.getChildCount());   treeModel.insertNodeInto(node2,root,root.getChildCount());    //创建节点node1的子节点并插入   DefaultMutableTreeNode leafnode = new DefaultMutableTreeNode("打开");   treeModel.insertNodeInto(leafnode,node1,node1.getChildCount());   leafnode = new DefaultMutableTreeNode("保存");   treeModel.insertNodeInto(leafnode,node1,node1.getChildCount());   leafnode = new DefaultMutableTreeNode("另存为");   treeModel.insertNodeInto(leafnode,node1,node1.getChildCount());   leafnode = new DefaultMutableTreeNode("关闭");   treeModel.insertNodeInto(leafnode,node1,node1.getChildCount());    //创建节点node2的子节点并插入   leafnode = new DefaultMutableTreeNode("剪切");   treeModel.insertNodeInto(leafnode,node2,node2.getChildCount());   leafnode = new DefaultMutableTreeNode("复制");   treeModel.insertNodeInto(leafnode,node2,node2.getChildCount());   leafnode = new DefaultMutableTreeNode("粘贴");   treeModel.insertNodeInto(leafnode,node2,node2.getChildCount());    //创建树对象   JTree tree = new JTree(treeModel);   //设置Tree的选择为一次只能选择一个节点   tree.getSelectionModel().setSelectionMode(        TreeSelectionModel.SINGLE_TREE_SELECTION);   //注册监听器   tree.addTreeSelectionListener(this);    tree.setRowHeight(20);    //创建节点绘制对象   DefaultTreeCellRenderer cellRenderer =        (DefaultTreeCellRenderer)tree.getCellRenderer();    //设置字体   cellRenderer.setFont(new Font("Serif",Font.PLAIN,14));   cellRenderer.setBackgroundNonSelectionColor(Color.white);   cellRenderer.setBackgroundSelectionColor(Color.yellow);   cellRenderer.setBorderSelectionColor(Color.red);    //设置选或不选时，文字的变化颜色   cellRenderer.setTextNonSelectionColor(Color.black);   cellRenderer.setTextSelectionColor(Color.blue);      //把树对象添加到内容面板   container.add(new JScrollPane(tree));    //创建标签   label = new JLabel("你当前选择的节点为：",JLabel.CENTER);   label.setFont(new Font("Serif",Font.PLAIN,14));   container.add(label,BorderLayout.SOUTH);    setVisible(true); //设置可见   setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //设置窗口关闭动作  }   //处理TreeSelectionEvent事件  public void valueChanged(TreeSelectionEvent event)  {   JTree tree = (JTree)event.getSource();   //获取目前选取的节点   DefaultMutableTreeNode selectionNode =    (DefaultMutableTreeNode)tree.getLastSelectedPathComponent();   String nodeName = selectionNode.toString();   label.setText("你当前选取的节点为： "+nodeName);  }   public static void main(String args[])  {   Tree d = new Tree();  }  }