Java详细解析下拉菜单和弹出菜单的使用

 package Swing;
 import javax.swing.*;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 public class CaiDan extends JFrame {
     public  CaiDan(){
         //创建菜单栏
         JMenuBar menuBar=new JMenuBar();
         //将菜单栏添加到JFrame窗口中
         this.setJMenuBar(menuBar);
         //创建菜单
         JMenu menu=new JMenu("操作");
         //将菜单添加到菜单栏上
         menuBar.add(menu);
         //创建两个菜单项
         JMenuItem item1=new JMenuItem("弹出窗口");
         JMenuItem item2=new JMenuItem("关闭");
         //为菜单项添加事件监听器
         item1.addActionListener(new ActionListener() {
             @Override
             public void actionPerformed(ActionEvent e) {
                 //创建一个JDialog窗口
                 JDialog dialog=new JDialog(CaiDan.this,true);
                 dialog.setTitle("弹出窗口");
                 dialog.setSize(200,200);
                 dialog.setLocation(50,50);
                 dialog.setVisible(true);
             }
         });
         item2.addActionListener(new ActionListener() {
             @Override
             public void actionPerformed(ActionEvent e) {
                 System.exit(0);
             }
         });
         //将菜单项添加到菜单中
         menu.add(item1);
         menu.addSeparator();
         menu.add(item2);
         this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         this.setSize(300,300);
         this.setVisible(true);
     }
     public static void main(String[] args) {
         new CaiDan();
     }
 }

 package Swing;
 import javax.swing.*;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
 public class TanChu extends JFrame {
     private JPopupMenu popupMenu;
     public TanChu(){
         //创建一个JPopupMenu菜单
         popupMenu=new JPopupMenu();
         //创建三个JMenuItem菜单项
         JMenuItem refreshItem=new JMenuItem("refresh");
         JMenuItem createItem=new JMenuItem("create");
         JMenuItem exitItem=new JMenuItem("exit");
         //为exitItem菜单项添加事件监听器
         exitItem.addActionListener(new ActionListener() {
             @Override
             public void actionPerformed(ActionEvent e) {
                 System.exit(0);
             }
         });
         //向JPopupMenu菜单添加菜单项
         popupMenu.add(refreshItem);
         popupMenu.add(createItem);
         popupMenu.addSeparator();
         popupMenu.add(exitItem);
         //向JFrame窗口添加clicked鼠标事件监听器
         this.addMouseListener(new MouseAdapter() {
             @Override
             public void mouseClicked(MouseEvent e) {
                 //通过值匹配，当点击右键的时候，显示JPopupMenu菜单
                if(e.getButton()==e.BUTTON3){
                    popupMenu.show(e.getComponent(),e.getX(),e.getY());
                }
             }
         });
         this.setSize(300,300);
         this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         this.setVisible(true);
     }
     public static void main(String[] args) {
         new TanChu();
     }
 }