java web 创建目录树导航答:import javax.swing.JFrame;import javax.swing.JMenu;import javax.swing.JMenuBar;import javax.swing.JMenuItem;public class MenuBarDemo extends JFrame { JMenuBar menuBar;JMenu file,edit,news;JMenuItem newsFile,javaFile,open,exit;JMenuItem undo,redo,copy,cut,paste,find,replace;public ...