控制台程序。

JMenuBar对象表示放在窗口顶部的菜单栏。可以为JMenuBar对象添加JMenu或JMenuItem对象，它们都显示在菜单栏上。JMenu对象是带有标签的菜单，单击就可以显示一列菜单项。JMenuItem对象表示菜单中带有标签的菜单项，单击就会执行某个程序动作。

// Main window for the Sketcher application

import javax.swing.*;

import static java.awt.event.InputEvent.*; // For modifier constants

@SuppressWarnings("serial")

public class SketcherFrame extends JFrame {

// Constructor

public SketcherFrame(String title) {

setTitle(title); // Set the window title

setDefaultCloseOperation(EXIT_ON_CLOSE);

setJMenuBar(menuBar); // Add the menu bar to the window

JMenu fileMenu = new JMenu("File"); // Create File menu

JMenu elementMenu = new JMenu("Elements"); // Create Elements menu

fileMenu.setMnemonic('F'); // Create shortcut

elementMenu.setMnemonic('E'); // Create shortcut

// Construct the file drop-down menu

newItem = fileMenu.add("New"); // Add New item

openItem = fileMenu.add("Open"); // Add Open item

closeItem = fileMenu.add("Close"); // Add Close item

fileMenu.addSeparator(); // Add separator

saveItem = fileMenu.add("Save"); // Add Save item

saveAsItem = fileMenu.add("Save As..."); // Add Save As item

fileMenu.addSeparator(); // Add separator

printItem = fileMenu.add("Print"); // Add Print item

// Add File menu accelerators

newItem.setAccelerator(KeyStroke.getKeyStroke('N',CTRL_DOWN_MASK ));

openItem.setAccelerator(KeyStroke.getKeyStroke('O', CTRL_DOWN_MASK));

saveItem.setAccelerator(KeyStroke.getKeyStroke('S', CTRL_DOWN_MASK));

printItem.setAccelerator(KeyStroke.getKeyStroke('P', CTRL_DOWN_MASK));

// Construct the Element drop-down menu

elementMenu.add(lineItem = new JRadioButtonMenuItem("Line", true));

elementMenu.add(rectangleItem = new JRadioButtonMenuItem("Rectangle", false));

elementMenu.add(circleItem = new JRadioButtonMenuItem("Circle", false));

elementMenu.add(curveItem = new JRadioButtonMenuItem("Curve", false));

ButtonGroup types = new ButtonGroup();

types.add(lineItem);

types.add(rectangleItem);

types.add(circleItem);

types.add(curveItem);

// Add element type accelerators

lineItem.setAccelerator(KeyStroke.getKeyStroke('L', CTRL_DOWN_MASK));

rectangleItem.setAccelerator(KeyStroke.getKeyStroke('E', CTRL_DOWN_MASK));

circleItem.setAccelerator(KeyStroke.getKeyStroke('I', CTRL_DOWN_MASK));

curveItem.setAccelerator(KeyStroke.getKeyStroke('V', CTRL_DOWN_MASK));

elementMenu.addSeparator();

JMenu colorMenu = new JMenu("Color"); // Color submenu

elementMenu.add(colorMenu); // Add the submenu

colorMenu.add(redItem = new JCheckBoxMenuItem("Red", false));

colorMenu.add(yellowItem = new JCheckBoxMenuItem("Yellow", false));

colorMenu.add(greenItem = new JCheckBoxMenuItem("Green", false));

colorMenu.add(blueItem = new JCheckBoxMenuItem("Blue", true));

// Add element color accelerators

redItem.setAccelerator(KeyStroke.getKeyStroke('R', CTRL_DOWN_MASK));

yellowItem.setAccelerator(KeyStroke.getKeyStroke('Y', CTRL_DOWN_MASK));

greenItem.setAccelerator(KeyStroke.getKeyStroke('G', CTRL_DOWN_MASK));

blueItem.setAccelerator(KeyStroke.getKeyStroke('B', CTRL_DOWN_MASK));

menuBar.add(fileMenu); // Add the file menu

menuBar.add(elementMenu); // Add the element menu

}

private JMenuBar menuBar = new JMenuBar(); // Window menu bar

// File menu items

private JMenuItem newItem, openItem, closeItem,

saveItem, saveAsItem, printItem;

// Element menu items

private JRadioButtonMenuItem lineItem, rectangleItem, circleItem, // Types

curveItem, textItem;

private JCheckBoxMenuItem redItem, yellowItem, // Colors

greenItem, blueItem ;

}

// Sketching application

import javax.swing.*;

import java.awt.*;

import javax.swing.SwingUtilities;

public class Sketcher {

public static void main(String[] args) {

SwingUtilities.invokeLater(new Runnable() {

public void run() {

createWindow();

}

});

}

public static void createWindow(){

window = new SketcherFrame("Sketcher"); // Create the app window

Toolkit theKit = window.getToolkit(); // Get the window toolkit

Dimension wndSize = theKit.getScreenSize(); // Get screen size

// Set the position to screen center & size to half screen size

window.setSize(wndSize.width/2, wndSize.height/2); // Set window size

window.setLocationRelativeTo(null); // Center window

window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

window.setVisible(true);

}

private static SketcherFrame window; // The application window

}