Java基础之处理事件——添加工具栏（Sketcher 7 with File toolbar buttons）

控制台程序。

工具栏在应用程序窗口中通常位于内容面板顶部的菜单栏下，包含直接访问菜单选项的按钮。在Sketcher程序中可以为最常用的菜单项添加工具栏。

工具栏是javax.swing.JToolBar类定义的Swing组件。想SketcherFrame类定义中添加如下域，可以为这个类添加一个用于工具栏的成员：

private JToolBar toolBar = new JToolBar();

为了把工具栏添加到应用程序窗口中，需要在SkecherFrame构造函数已有代码的后面添加如下语句：

getContentPane().add(toolBar,BorderLayout.NORTH);

对图标的引用一般存储在javax.swing.Icon类型的变量中，javax.swing.Icon是接口，其中声明的方法getHeight()和getWidth()分别用来返回图标的高度和宽度（以像素为单位）。Icon接口还声明了paint()方法，用来在组件上绘制图标图像。javax.swing.ImageIcon类实现了Icon接口，使用这个类在程序中通过包含定义图标图像数据的文件来创建图标对象。

ImageIcon类有多个构造函数，这里使用的构造函数仅仅接收一个String参数，这个参数指定了包含图标图像的文件的路径。传送为参数的String对象可以只是文件名，此时文件应位于Sketcher执行时的当前目录下。

在自定义包中指定图标文件的路径：

 // Defines application wide constants
 package Constants;
 import java.awt.Color;
 import javax.swing.*;

 public class SketcherConstants {
   // Path for images
   public final static String imagePath = "E:/JavaProject/BeginningJava/Images/";

   // Toolbar icons
   public final static Icon NEW24 = new ImageIcon(imagePath + "New24.gif");
   public final static Icon OPEN24 = new ImageIcon(imagePath + "Open24.gif");
   public final static Icon SAVE24 = new ImageIcon(imagePath + "Save24.gif");
   public final static Icon SAVEAS24 = new ImageIcon(imagePath + "SaveAs24.gif");
   public final static Icon PRINT24 = new ImageIcon(imagePath + "Print24.gif");

   // Element type definitions
   public final static int LINE      = 101;
   public final static int RECTANGLE = 102;
   public final static int CIRCLE    = 103;
   public final static int CURVE     = 104;

   // Initial conditions
   public final static int DEFAULT_ELEMENT_TYPE = LINE;
   public final static Color DEFAULT_ELEMENT_COLOR = Color.BLUE;
 }

 // Frame for the Sketcher application
 import javax.swing.*;
 import javax.swing.border.*;
 import java.awt.event.*;
 import java.awt.*;

 import static java.awt.event.InputEvent.*;
 import static java.awt.AWTEvent.*;
 import static java.awt.Color.*;
 import static Constants.SketcherConstants.*;
 import static javax.swing.Action.*;

 @SuppressWarnings("serial")
 public class SketcherFrame extends JFrame {
   // Constructor
   public SketcherFrame(String title) {
     setTitle(title);                                                   // Set the window title
     setJMenuBar(menuBar);                                              // Add the menu bar to the window
     setDefaultCloseOperation(EXIT_ON_CLOSE);                           // Default is exit the application

     createFileMenu();                                                  // Create the File menu
     createElementMenu();                                               // Create the element menu
     createColorMenu();                                                 // Create the element menu
     createToolbar();
     toolBar.setRollover(true);
     getContentPane().add(toolBar, BorderLayout.NORTH);
   }

   // Create File menu item actions
   private void createFileMenuActions() {
     newAction = new FileAction("New", 'N', CTRL_DOWN_MASK);
     openAction = new FileAction("Open", 'O', CTRL_DOWN_MASK);
     closeAction = new FileAction("Close");
     saveAction = new FileAction("Save", 'S', CTRL_DOWN_MASK);
     saveAsAction = new FileAction("Save As...");
     printAction = new FileAction("Print", 'P', CTRL_DOWN_MASK);
     exitAction = new FileAction("Exit", 'X', CTRL_DOWN_MASK);

     // Initialize the array
     FileAction[] actions = {openAction, closeAction, saveAction, saveAsAction, printAction, exitAction};
     fileActions = actions;

     // Add toolbar icons
     newAction.putValue(LARGE_ICON_KEY, NEW24);
     openAction.putValue(LARGE_ICON_KEY, OPEN24);
     saveAction.putValue(LARGE_ICON_KEY, SAVE24);
     saveAsAction.putValue(LARGE_ICON_KEY, SAVEAS24);
     printAction.putValue(LARGE_ICON_KEY, PRINT24);
   }

   // Create the File menu
   private void createFileMenu() {
     JMenu fileMenu = new JMenu("File");                                // Create File menu
     fileMenu.setMnemonic('F');                                         // Create shortcut
     createFileMenuActions();                                           // Create Actions for File menu item

     // Construct the file drop-down menu
     fileMenu.add(newAction);                                           // New Sketch menu item
     fileMenu.add(openAction);                                          // Open sketch menu item
     fileMenu.add(closeAction);                                         // Close sketch menu item
     fileMenu.addSeparator();                                           // Add separator
     fileMenu.add(saveAction);                                          // Save sketch to file
     fileMenu.add(saveAsAction);                                        // Save As menu item
     fileMenu.addSeparator();                                           // Add separator
     fileMenu.add(printAction);                                         // Print sketch menu item
     fileMenu.addSeparator();                                           // Add separator
     fileMenu.add(exitAction);                                          // Print sketch menu item
     menuBar.add(fileMenu);                                             // Add the file menu
   }

   // Create Element menu actions
   private void createElementTypeActions() {
     lineAction = new TypeAction("Line", LINE, 'L', CTRL_DOWN_MASK);
     rectangleAction = new TypeAction("Rectangle", RECTANGLE, 'R', CTRL_DOWN_MASK);
     circleAction =  new TypeAction("Circle", CIRCLE,'C', CTRL_DOWN_MASK);
     curveAction = new TypeAction("Curve", CURVE,'U', CTRL_DOWN_MASK);

     // Initialize the array
     TypeAction[] actions = {lineAction, rectangleAction, circleAction, curveAction};
     typeActions = actions;
   }

   // Create the Elements menu
   private void createElementMenu() {
     createElementTypeActions();
     JMenu elementMenu = new JMenu("Elements");                         // Create Elements menu
     elementMenu.setMnemonic('E');                                      // Create shortcut
     createRadioButtonDropDown(elementMenu, typeActions, lineAction);
     menuBar.add(elementMenu);                                          // Add the element menu
   }

   // Create Color menu actions
   private void createElementColorActions() {
     redAction = new ColorAction("Red", RED, 'R', CTRL_DOWN_MASK|ALT_DOWN_MASK);
     yellowAction = new ColorAction("Yellow", YELLOW, 'Y', CTRL_DOWN_MASK|ALT_DOWN_MASK);
     greenAction = new ColorAction("Green", GREEN, 'G', CTRL_DOWN_MASK|ALT_DOWN_MASK);
     blueAction = new ColorAction("Blue", BLUE, 'B', CTRL_DOWN_MASK|ALT_DOWN_MASK);

     // Initialize the array
     ColorAction[] actions = {redAction, greenAction, blueAction, yellowAction};
     colorActions = actions;
   }

   // Create the Color menu
   private void createColorMenu() {
     createElementColorActions();
     JMenu colorMenu = new JMenu("Color");                              // Create Elements menu
     colorMenu.setMnemonic('C');                                        // Create shortcut
     createRadioButtonDropDown(colorMenu, colorActions, blueAction);
     menuBar.add(colorMenu);                                            // Add the color menu
   }

   // Menu creation helper
   private void createRadioButtonDropDown(JMenu menu, Action[] actions, Action selected) {
     ButtonGroup group = new ButtonGroup();
     JRadioButtonMenuItem item = null;
     for(Action action : actions) {
       group.add(menu.add(item = new JRadioButtonMenuItem(action)));
       if(action == selected) {
         item.setSelected(true);                                        // This is default selected
       }
     }
   }

   // Create toolbar buttons on the toolbar
   private void createToolbar() {
     for(FileAction action: fileActions){
       if(action != exitAction && action != closeAction)
         addToolbarButton(action);                                      // Add the toolbar button
     }
  }

   // Create and add a toolbar button
   private void addToolbarButton(Action action) {
     JButton button = new JButton(action);                              // Create from Action
     button.setBorder(BorderFactory.createCompoundBorder(               // Add button border
            new EmptyBorder(2,5,5,2),                                   // Outside border
            BorderFactory.createRaisedBevelBorder()));                  // Inside border
     button.setHideActionText(true);                                    // No label on the button
     toolBar.add(button);                                               // Add the toolbar button
   }

   // Inner class defining Action objects for File menu items
   class FileAction extends AbstractAction {
     // Create action with a name
     FileAction(String name) {
       super(name);
     }

     // Create action with a name and accelerator
     FileAction(String name, char ch, int modifiers) {
       super(name);
       putValue(ACCELERATOR_KEY, KeyStroke.getKeyStroke(ch, modifiers));

       // Now find the character to underline
       int index = name.toUpperCase().indexOf(ch);
       if(index != -1) {
         putValue(DISPLAYED_MNEMONIC_INDEX_KEY, index);
       }
     }

     // Event handler
     public void actionPerformed(ActionEvent e) {
       // You will add action code here eventually...
     }
   }

   // Inner class defining Action objects for Element type menu items
   class TypeAction extends AbstractAction {
     // Create action with just a name property
     TypeAction(String name, int typeID) {
       super(name);
       this.typeID = typeID;
     }

     // Create action with a name and an accelerator
     private TypeAction(String name,int typeID, char ch, int modifiers) {
       this(name, typeID);
       putValue(ACCELERATOR_KEY, KeyStroke.getKeyStroke(ch, modifiers));

       // Now find the character to underline
       int index = name.toUpperCase().indexOf(ch);
       if(index != -1) {
         putValue(DISPLAYED_MNEMONIC_INDEX_KEY, index);
       }
     }

     public void actionPerformed(ActionEvent e) {
       elementType = typeID;
     }

     private int typeID;
   }

   // Handles color menu items
   class ColorAction  extends AbstractAction {
     // Create an action with a name and a color
     public ColorAction(String name, Color color) {
       super(name);
       this.color = color;
     }

     // Create an action with a name, a color, and an accelerator
     public ColorAction(String name, Color color, char ch, int modifiers) {
       this(name, color);
       putValue(ACCELERATOR_KEY, KeyStroke.getKeyStroke(ch, modifiers));

       // Now find the character to underline
       int index = name.toUpperCase().indexOf(ch);
       if(index != -1) {
         putValue(DISPLAYED_MNEMONIC_INDEX_KEY, index);
       }
     }

     public void actionPerformed(ActionEvent e) {
       elementColor = color;
     }

     private Color color;
   }

   // File actions
   private FileAction newAction, openAction, closeAction, saveAction, saveAsAction, printAction, exitAction;
   private FileAction[] fileActions;                                    // File actions as an array

   // Element type actions
   private TypeAction lineAction, rectangleAction, circleAction, curveAction;
   private TypeAction[] typeActions;                                    // Type actions as an array

 // Element color actions
   private ColorAction redAction, yellowAction,greenAction, blueAction;
   private ColorAction[] colorActions;                                  // Color actions as an array

   private JMenuBar menuBar = new JMenuBar();                           // Window menu bar
   private Color elementColor = DEFAULT_ELEMENT_COLOR;                  // Current element color
   private int elementType = DEFAULT_ELEMENT_TYPE;                      // Current element type
   private JToolBar toolBar = new JToolBar();                           // Window toolbar
 }

 // Sketching application
 import javax.swing.*;
 import java.awt.*;
 import java.awt.event.*;

 public class Sketcher {
   public static void main(String[] args) {
      theApp = new Sketcher();                                          // Create the application object
    SwingUtilities.invokeLater(new Runnable() {
             public void run() {
                           theApp.createGUI();                          // Call GUI creator
             }
         });
   }

   // Method to create the application GUI
   private void createGUI() {
     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.addWindowListener(new WindowHandler());                     // Add window listener
     window.setVisible(true);
   }

   // Handler class for window events
   class WindowHandler extends WindowAdapter {
     // Handler for window closing event
     @Override
     public void windowClosing(WindowEvent e) {
       // Code to be added here...
     }
   }

   private SketcherFrame window;                                        // The application window
   private static Sketcher theApp;                                      // The application object
 }