Java之事件处理

监听器

ActionListener接口 ——通常用自己创建的新类implements接口

建议使用匿名内部类实现，因为内部类可以访问类内的变量，而匿名类可以大大简化代码，不需要构造函数。

实例：处理按钮点击事件

 1 package button;
 2 
 3 import java.awt.*;
 4 import java.awt.event.*;
 5 import javax.swing.*;
 6 
 7 /**
 8  * A frame with a button panel
 9  */
10 public class ButtonFrame extends JFrame
11 {
12    private JPanel buttonPanel;
13    private static final int DEFAULT_WIDTH = 300;
14    private static final int DEFAULT_HEIGHT = 200;
15 
16    public ButtonFrame()
17    {      
18       setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
19 
20       // create buttons
21       JButton yellowButton = new JButton("Yellow");
22       JButton blueButton = new JButton("Blue");
23       JButton redButton = new JButton("Red");
24 
25       buttonPanel = new JPanel();
26 
27       // add buttons to panel
28       buttonPanel.add(yellowButton);
29       buttonPanel.add(blueButton);
30       buttonPanel.add(redButton);
31 
32       // add panel to frame
33       add(buttonPanel);
34 
35       // create button actions
36       ColorAction yellowAction = new ColorAction(Color.YELLOW);
37       ColorAction blueAction = new ColorAction(Color.BLUE);
38       ColorAction redAction = new ColorAction(Color.RED);
39 
40       // associate actions with buttons
41       yellowButton.addActionListener(yellowAction);
42       blueButton.addActionListener(blueAction);
43       redButton.addActionListener(redAction);
44    }
45 
46    /**
47     * An action listener that sets the panel's background color.
48     */
49    private class ColorAction implements ActionListener
50    {
51       private Color backgroundColor;
52 
53       public ColorAction(Color c)
54       {
55          backgroundColor = c;
56       }
57 
58       public void actionPerformed(ActionEvent event)
59       {
60          buttonPanel.setBackground(backgroundColor);
61       }
62    }
63 }

View Code