Swing 菜单JMenu

  Swing菜单和菜单项是按钮，因为JMenuItem扩展AbstractButton，JMenu扩展JMenuItem。因此，Swing菜单和菜单项继承了如下功能，即包含文本和（或)图标、显示光标进入时的图标和助记符等。 
　　JMenuItem和JMenu的父组件，它们最后都归于java.awt.Container，以强调菜单和菜单项都是容器。可以把任何类型的组件（从包含一个动画GIF的标签到JTree的一个实例）添加到一个菜单或菜单项中。 
　　菜单和菜单项还实现MenuElement接口，以便参与菜单事件的处理。 
　　工具条和弹出式菜单都扩展JComponent类，即任意组件都可以添加到一个工具条或弹出式菜单中。 
　　本章将介绍下面的组件： 
　　•JMenuItem 
　　•JCheckBoxMenuItem 
　　•JRadioButtonMenuItem 
　　•JMenu 
　　•JPopupMenu 
　　•JMenuBar 

例子 1：在菜单中增加复选菜单 

 import java.awt.event.KeyEvent;
 import javax.swing.JCheckBoxMenuItem;
 import javax.swing.JFrame;
 import javax.swing.JMenu;
 import javax.swing.JMenuBar;
 import javax.swing.JMenuItem;
 public class JCheckBoxMenuItemDemo {
   public static void main(final String args[]) {
     JFrame frame = new JFrame("MenuSample Example");
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     JMenuBar menuBar = new JMenuBar();
     // File Menu, F - Mnemonic
     JMenu fileMenu = new JMenu("File");
     fileMenu.setMnemonic(KeyEvent.VK_F);
     menuBar.add(fileMenu);
     // File->New, N - Mnemonic
     JMenuItem newMenuItem = new JMenuItem("New", KeyEvent.VK_N);
     fileMenu.add(newMenuItem);
     JCheckBoxMenuItem caseMenuItem = new JCheckBoxMenuItem("Case Sensitive");
     caseMenuItem.setMnemonic(KeyEvent.VK_C);
     fileMenu.add(caseMenuItem);

     frame.setJMenuBar(menuBar);
     frame.setSize(350, 250);
     frame.setVisible(true);
   }
 }

 

例2：菜单事件处理 

 import java.awt.Container;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.awt.event.ItemEvent;
 import java.awt.event.ItemListener;
 import java.awt.event.WindowAdapter;
 import java.awt.event.WindowEvent;
 import javax.swing.AbstractButton;
 import javax.swing.ButtonGroup;
 import javax.swing.JCheckBoxMenuItem;
 import javax.swing.JFrame;
 import javax.swing.JMenu;
 import javax.swing.JMenuBar;
 import javax.swing.JMenuItem;
 import javax.swing.JRadioButtonMenuItem;
 import javax.swing.JSeparator;
 import javax.swing.JTextField;
 public class SwingWinMenus extends JFrame {
   public static int WIDTH = 300;
   public static int HEIGHT = 300;
   public static String TITLE = "SwingWin";
   Container frameContainer;
   JTextField textField = new JTextField(50);
   JMenuBar menuBar = new JMenuBar();
   JMenu fileMenu = new JMenu("File");
   JMenuItem fileNew = new JMenuItem("New");
   JMenuItem fileOpen = new JMenuItem("Open");
   JMenuItem fileSave = new JMenuItem("Save");
   JMenuItem fileExit = new JMenuItem("Exit");
   JMenu editMenu = new JMenu("Edit");
   JMenuItem editCut = new JMenuItem("Cut");
   JMenuItem editCopy = new JMenuItem("Copy");
   JMenuItem editPaste = new JMenuItem("Paste");
   JMenu specialMenu = new JMenu("Special");
   JCheckBoxMenuItem specialCheck1 = new JCheckBoxMenuItem("Check 1");
   JCheckBoxMenuItem specialCheck2 = new JCheckBoxMenuItem("Check 2", true);
   JSeparator separator = new JSeparator();
   JRadioButtonMenuItem specialRadio1 = new JRadioButtonMenuItem("Radio 1");
   JRadioButtonMenuItem specialRadio2 = new JRadioButtonMenuItem("Radio 2");
   ButtonGroup buttonGroup = new ButtonGroup();
   public SwingWinMenus() {
     super("");
     fileMenu.add(fileNew);
     fileMenu.add(fileOpen);
     fileMenu.add(fileSave);
     fileMenu.add(fileExit);
     editMenu.add(editCut);
     editMenu.add(editCopy);
     editMenu.add(editPaste);
     specialMenu.add(specialCheck1);
     specialMenu.add(specialCheck2);
     specialMenu.add(separator);
     buttonGroup.add(specialRadio1);
     buttonGroup.add(specialRadio2);
     specialMenu.add(specialRadio1);
     specialMenu.add(specialRadio2);
     menuBar.add(fileMenu);
     menuBar.add(editMenu);
     menuBar.add(specialMenu);
     setJMenuBar(menuBar);
     frameContainer = getContentPane();
     frameContainer.setLayout(null);
     textField.setBounds(100, 100, 100, 20);
     frameContainer.add(textField);
     setupEventHandlers();
     setSize(450, 450);
     setVisible(true);
   }
   void setupEventHandlers() {
     addWindowListener(new WindowHandler());
     fileNew.addActionListener(new MenuItemHandler());
     fileOpen.addActionListener(new MenuItemHandler());
     fileSave.addActionListener(new MenuItemHandler());
     fileExit.addActionListener(new MenuItemHandler());
     editCut.addActionListener(new MenuItemHandler());
     editCopy.addActionListener(new MenuItemHandler());
     editPaste.addActionListener(new MenuItemHandler());
     specialCheck1.addItemListener(new ItemHandler());
     specialCheck2.addItemListener(new ItemHandler());
     specialRadio1.addItemListener(new ItemHandler());
     specialRadio2.addItemListener(new ItemHandler());
   }
   public static void main(String[] args) {
     SwingWinMenus app = new SwingWinMenus();
   }
   public class WindowHandler extends WindowAdapter {
     public void windowClosing(WindowEvent e) {
       System.exit(0);
     }
   }
   public class MenuItemHandler implements ActionListener {
     public void actionPerformed(ActionEvent e) {
       String cmd = e.getActionCommand();
       if (cmd.equals("Exit"))
         System.exit(0);
       else
         textField.setText(cmd);
     }
   }
   public class ItemHandler implements ItemListener {
     public void itemStateChanged(ItemEvent e) {
       AbstractButton button = (AbstractButton) e.getItem();
       String label = button.getText();
       if (button.isSelected())
         label += " true";
       else
         label += " false";
       textField.setText(label);
     }
   }
 }

 

例3：弹出试菜单 

 import java.awt.Dimension;
 import javax.swing.JButton;
 import javax.swing.JFrame;
 import javax.swing.JMenuItem;
 import javax.swing.JPopupMenu;
 import javax.swing.event.PopupMenuEvent;
 import javax.swing.event.PopupMenuListener;
 // Define PopupMenuListener
 class MyPopupMenuListener implements PopupMenuListener {
   public void popupMenuCanceled(PopupMenuEvent popupMenuEvent) {
     System.out.println("Canceled");
   }
   public void popupMenuWillBecomeInvisible(PopupMenuEvent popupMenuEvent) {
     System.out.println("Becoming Invisible");
   }
   public void popupMenuWillBecomeVisible(PopupMenuEvent popupMenuEvent) {
     System.out.println("Becoming Visible");
   }
 }
 public class PopupMenuListenerDemo {
   public static void main(final String args[]) {
     JFrame frame = new JFrame("PopupSample Example");
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     // Create popup menu, attach popup menu listener
     JPopupMenu popupMenu = new JPopupMenu("Title");
     popupMenu.setSize(new Dimension(100,50));
     PopupMenuListener popupMenuListener = new MyPopupMenuListener();
     popupMenu.addPopupMenuListener(popupMenuListener);
     // Cut
     JMenuItem cutMenuItem = new JMenuItem("Cut");
     popupMenu.add(cutMenuItem);
     // Copy
     JMenuItem copyMenuItem = new JMenuItem("Copy");
     popupMenu.add(copyMenuItem);
     // Paste
     JMenuItem pasteMenuItem = new JMenuItem("Paste");
     pasteMenuItem.setEnabled(false);
     popupMenu.add(pasteMenuItem);
     // Separator
     popupMenu.addSeparator();
     // Find
     JMenuItem findMenuItem = new JMenuItem("Find");
     popupMenu.add(findMenuItem);
     JButton label = new JButton();
     frame.add(label);
     label.setComponentPopupMenu(popupMenu);
     frame.setSize(350, 250);
     frame.setVisible(true);
   }
 }

 

例 4：给菜单增加快捷方式 

 import java.awt.event.KeyEvent;
 import javax.swing.JFrame;
 import javax.swing.JMenu;
 import javax.swing.JMenuBar;
 import javax.swing.JMenuItem;
 import javax.swing.KeyStroke;
 public class JMenuItemKeyStroke {
   public static void main(final String args[]) {
     JFrame frame = new JFrame("MenuSample Example");
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     JMenuBar menuBar = new JMenuBar();
     // File Menu, F - Mnemonic
     JMenu fileMenu = new JMenu("File");
     fileMenu.setMnemonic(KeyEvent.VK_F);
     menuBar.add(fileMenu);
     // File->New, N - Mnemonic
     JMenuItem newMenuItem = new JMenuItem("New", KeyEvent.VK_N);
     fileMenu.add(newMenuItem);
     // Edit->Cut, T - Mnemonic, CTRL-X - Accelerator
     JMenuItem cutMenuItem = new JMenuItem("Cut", KeyEvent.VK_T);
     KeyStroke ctrlXKeyStroke = KeyStroke.getKeyStroke("control X");
     cutMenuItem.setAccelerator(ctrlXKeyStroke);
     fileMenu.add(cutMenuItem);
     frame.setJMenuBar(menuBar);
     frame.setSize(350, 250);
     frame.setVisible(true);
   }
 }