Java基础之创建窗口——向窗口中添加菜单（Sketcher）

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。

 1 // Main window for the Sketcher application
 2 import javax.swing.*;
 3 import static java.awt.event.InputEvent.*;                             // For modifier constants
 4 
 5 @SuppressWarnings("serial")
 6 public class SketcherFrame extends JFrame {
 7   // Constructor
 8   public SketcherFrame(String title) {
 9     setTitle(title);                                                   // Set the window title
10     setDefaultCloseOperation(EXIT_ON_CLOSE);
11 
12     setJMenuBar(menuBar);                                              // Add the menu bar to the window
13 
14     JMenu fileMenu = new JMenu("File");                                // Create File menu
15     JMenu elementMenu = new JMenu("Elements");                         // Create Elements menu
16     fileMenu.setMnemonic('F');                                         // Create shortcut
17     elementMenu.setMnemonic('E');                                      // Create shortcut
18 
19     // Construct the file drop-down menu
20     newItem = fileMenu.add("New");                                      // Add New item
21     openItem = fileMenu.add("Open");                                    // Add Open item
22     closeItem = fileMenu.add("Close");                                  // Add Close item
23     fileMenu.addSeparator();                                            // Add separator
24     saveItem = fileMenu.add("Save");                                    // Add Save item
25     saveAsItem = fileMenu.add("Save As...");                            // Add Save As item
26     fileMenu.addSeparator();                                            // Add separator
27     printItem = fileMenu.add("Print");                                  // Add Print item
28 
29     // Add File menu accelerators
30     newItem.setAccelerator(KeyStroke.getKeyStroke('N',CTRL_DOWN_MASK ));
31     openItem.setAccelerator(KeyStroke.getKeyStroke('O', CTRL_DOWN_MASK));
32     saveItem.setAccelerator(KeyStroke.getKeyStroke('S', CTRL_DOWN_MASK));
33     printItem.setAccelerator(KeyStroke.getKeyStroke('P', CTRL_DOWN_MASK));
34 
35     // Construct the Element drop-down menu
36     elementMenu.add(lineItem = new JRadioButtonMenuItem("Line", true));
37     elementMenu.add(rectangleItem = new JRadioButtonMenuItem("Rectangle", false));
38     elementMenu.add(circleItem = new JRadioButtonMenuItem("Circle", false));
39     elementMenu.add(curveItem = new JRadioButtonMenuItem("Curve", false));
40     ButtonGroup types = new ButtonGroup();
41     types.add(lineItem);
42     types.add(rectangleItem);
43     types.add(circleItem);
44     types.add(curveItem);
45 
46     // Add element type accelerators
47     lineItem.setAccelerator(KeyStroke.getKeyStroke('L', CTRL_DOWN_MASK));
48     rectangleItem.setAccelerator(KeyStroke.getKeyStroke('E', CTRL_DOWN_MASK));
49     circleItem.setAccelerator(KeyStroke.getKeyStroke('I', CTRL_DOWN_MASK));
50     curveItem.setAccelerator(KeyStroke.getKeyStroke('V', CTRL_DOWN_MASK));
51 
52     elementMenu.addSeparator();
53     JMenu colorMenu = new JMenu("Color");                              // Color submenu
54     elementMenu.add(colorMenu);                                        // Add the submenu
55     colorMenu.add(redItem = new JCheckBoxMenuItem("Red", false));
56     colorMenu.add(yellowItem = new JCheckBoxMenuItem("Yellow", false));
57     colorMenu.add(greenItem = new JCheckBoxMenuItem("Green", false));
58     colorMenu.add(blueItem = new JCheckBoxMenuItem("Blue", true));
59 
60     // Add element color accelerators
61     redItem.setAccelerator(KeyStroke.getKeyStroke('R', CTRL_DOWN_MASK));
62     yellowItem.setAccelerator(KeyStroke.getKeyStroke('Y', CTRL_DOWN_MASK));
63     greenItem.setAccelerator(KeyStroke.getKeyStroke('G', CTRL_DOWN_MASK));
64     blueItem.setAccelerator(KeyStroke.getKeyStroke('B', CTRL_DOWN_MASK));
65 
66     menuBar.add(fileMenu);                                             // Add the file menu
67     menuBar.add(elementMenu);                                          // Add the element menu
68   }
69 
70   private JMenuBar menuBar = new JMenuBar();                           // Window menu bar
71 
72   // File menu items
73   private JMenuItem newItem,  openItem,   closeItem,
74                     saveItem, saveAsItem, printItem;
75 
76   // Element menu items
77   private JRadioButtonMenuItem lineItem,  rectangleItem, circleItem,   // Types
78                                curveItem, textItem;
79   private JCheckBoxMenuItem    redItem,   yellowItem,                  // Colors
80                                greenItem, blueItem ;
81 }

 1 // Sketching application
 2 import javax.swing.*;
 3 import java.awt.*;
 4 
 5 import javax.swing.SwingUtilities;
 6 
 7 public class Sketcher {
 8   public static void main(String[] args) {
 9     SwingUtilities.invokeLater(new Runnable() {
10             public void run() {
11                 createWindow();
12             }
13         });
14   }
15 
16   public static void createWindow(){
17     window = new SketcherFrame("Sketcher");                            // Create the app window
18     Toolkit theKit = window.getToolkit();                              // Get the window toolkit
19     Dimension wndSize = theKit.getScreenSize();                        // Get screen size
20 
21     // Set the position to screen center & size to half screen size
22     window.setSize(wndSize.width/2, wndSize.height/2);                 // Set window size
23     window.setLocationRelativeTo(null);                                // Center window
24     window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
25 
26     window.setVisible(true);
27   }
28 
29   private static SketcherFrame window;                                 // The application window
30 }