Java事件处理——按钮和按键映射到动作对象

目标：实现按下CTRL+Y、CTRL+B或CTRL+R来改变面板颜色
Swing包的Action接口封装了命令，将它们连接到多个事件源。

java代码如下：
ActionFrame.java

package simpleframe;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class ActionFrame extends JFrame{    private JPanel buttonPanel;    private static final int DEFAULT_WIDTH = 300;    private static final int DEFAULT_HEIGHT = 200;    public ActionFrame(){        setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);        buttonPanel = new JPanel();        //定义action        Action yellowAction = new ColorAction("黄色", new ImageIcon("yellow-ball.gif"), Color.YELLOW);        Action blueAction = new ColorAction("蓝色", new ImageIcon("blue-ball.gif"), Color.BLUE);        Action redAction = new ColorAction("红色", new ImageIcon("red-ball.gif"), Color.RED);        //给button添加动作        buttonPanel.add(new JButton(yellowAction));        buttonPanel.add(new JButton(blueAction));        buttonPanel.add(new JButton(redAction));        //把panel加到frame中        add(buttonPanel);        //关联Y,B,R 键和名字        InputMap imap = buttonPanel.getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);        imap.put(KeyStroke.getKeyStroke("ctrl Y"), "panel.yellow");        imap.put(KeyStroke.getKeyStroke("ctrl B"), "panel.blue");        imap.put(KeyStroke.getKeyStroke("ctrl R"), "panel.red");        //关联名字和动作        ActionMap amap = buttonPanel.getActionMap();        amap.put("panel.yellow", yellowAction);        amap.put("panel.blue", blueAction);        amap.put("panel.red", redAction);    }    public class ColorAction extends AbstractAction{//AbstractAction类实现了Action接口除actionPerformed方法之外的所有六个方法        /**         * 构造一个color action         * @param name button显示的名字         * @param icon button显示的图标         * @param c 背景颜色         */        public ColorAction(String name, Icon icon, Color c) {            putValue(Action.NAME, name);            putValue(Action.SMALL_ICON, icon);            putValue(Action.SHORT_DESCRIPTION, "设置面板颜色为" + name.toLowerCase());            putValue("color", c);        }        @Override        public void actionPerformed(ActionEvent arg0) {            Color c = (Color)getValue("color");            buttonPanel.setBackground(c);        }    }    public static void main(String[] args) {        EventQueue.invokeLater(new Runnable()        {           public void run()           {              JFrame frame = new ActionFrame();              frame.setTitle("ActionColor");              frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);              frame.setVisible(true);           }        });    }}

运行结果如下图：