功能：实现创建一个树形菜单
说明：创建树形菜单结构与创建菜单栏类似，是按层次与模型创建的。
通过DefaultMutableTreeNode类创建根节点、子节点和孙节点对象，再通过DefaultTreeModel
类利用根节点创建树模型对象，然后通过treeModel.insertNodeInto方法将节点对象插入树模型中。
效果图：
代码：
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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();
}
}
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本文按层次与模型创建的树形菜单，与创建菜单栏类似，不知道小伙伴们有没有掌握呐？