下面是将按钮和按键映射到不同动作对象上的实例程序。
package action;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ActionFrame extends JFrame {
private static final long serialVersionUID = 1L;
public static void main(String[] args) {
ActionFrame actionFrame = new ActionFrame();
actionFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
actionFrame.setVisible(true);
}
private JPanel buttonPanel;
private static final int DEFAULT_WIDTH = 500;
private static final int DEFAULT_HEIGHT = 300;
public ActionFrame() {
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
buttonPanel = new JPanel();
//创造动作
Action yellowAction = new ColorAction("Yellow", new ImageIcon("yellow-ball.gif"), Color.YELLOW);
Action blueAction = new ColorAction("Blue", new ImageIcon("blue-ball.gif"), Color.BLUE);
Action redAction = new ColorAction("Red", new ImageIcon("red-ball.gif"), Color.RED);
//将动作和按钮关联
buttonPanel.add(new JButton(yellowAction));
buttonPanel.add(new JButton(blueAction));
buttonPanel.add(new JButton(redAction));
add(buttonPanel);
//将输入动作对象添加到击键上,并为每个击键命名
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");
//将输入键与执行动作映射
ActionMap amap = buttonPanel.getActionMap();
//将击键与动作关联起来
amap.put("panel.yellow", yellowAction);
amap.put("panel.blue", blueAction);
amap.put("panel.red", redAction);
}
public class ColorAction extends AbstractAction{
private static final long serialVersionUID = 1L;
public ColorAction(String name, Icon icon, Color c) {
putValue(Action.NAME, name);
putValue(Action.SMALL_ICON, icon);
putValue(Action.SHORT_DESCRIPTION, "Set panel color to" + name.toLowerCase());
putValue("color", c);
}
//事件处理
public void actionPerformed(ActionEvent event){
Color c = (Color) getValue("color");
buttonPanel.setBackground(c);
}
}
}
void putValue(String key, Object value)
将名/值放置在动作对象内。
key :用动作对象存储的名字。
value :与名字关联的对象Object getValue(String key)
返回被储存动作对象的值。static KeyStroke getKeyStroke(String description)
根据便于阅读的说明创建一个按键(由空格分隔的字符串序列) 例如,ctrl r。ActionMap getActionMap()
返回关联动作键和动作对象的映射InputMap getInputMap(int flag)
获得将按键映射到动作键的输入映射
学习Java核心技术卷一第八章第二节