《Java编程思想》读书笔记（9）
一些listene接口中只定义了一个方法，因此要实现这种接口的工作量并不大，因为只要写完这一个方法，接口也就实现了。但是如果要使用有多个方法的listener的话，就会比较麻烦了，因为必须要实现接口中定义的所有方法，而实际上很多方法我们并不需要。举例来说，如果要捕捉鼠标点击的话，那就必须写一个mouseClicked( )方法。但是由于MouseListener是一个interface，所以即使MouseListener定义的其他方法我们不使用，也得实现其所有的方法。 为了解决这个问题，有些(但不是全部)多方法的listener接口提供了适配器(adapter)。适配器会为接口提供默认的空方法。这样，你只要继承适配器，根据需要覆写方法就可以了。 例如： package com.vitamin.UI; import java.awt.BorderLayout; import java.awt.Container; import java.awt.Event; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.MouseAdapter; import java.awt.event.*; import javax.swing.*; public class HelloForm extends JFrame { private JLabel lbInfo = null; private JButton btnOK = null; public HelloForm() { super(); } public HelloForm(String title) { super(title); this.initForm(); } private void initForm() { this.lbInfo = new JLabel(); this.btnOK = new JButton("确定"); this.btnOK.addMouseListener(new MouseAdapter() { public void mouseClicked(MouseEvent e) { lbInfo.setText("hello,world"); } }); Container con = this.getContentPane(); con.setLayout(new BorderLayout()); con.add(this.btnOK,BorderLayout.SOUTH); con.add(this.lbInfo,BorderLayout.NORTH); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setSize(300,300); this.setVisible(true); } /** * @param args */ public static void main(String[] args) { HelloForm hf = new HelloForm("内部匿名类测试程序"); } } 在附上<<TIJ>>中给出的一段处理多个事件的代码： package com.vitamin.UI; import javax.swing.*; import java.awt.*; import java.awt.event.*; import java.util.*; import com.vitamin.Console.console; public class TrackEvent extends JApplet { private HashMap h = new HashMap(); private String[] event = { "focusGained", "focusLost", "keyPressed", "keyReleased", "keyTyped", "mouseClicked", "mouseEntered", "mouseExited", "mousePressed", "mouseReleased", "mouseDragged", "mouseMoved" }; private MyButton b1 = new MyButton(Color.BLUE, "test1"), b2 = new MyButton(Color.RED, "test2"); class MyButton extends JButton { void report(String field, String msg) { ((JTextField)h.get(field)).setText(msg); } FocusListener fl = new FocusListener() { public void focusGained(FocusEvent e) { report("focusGained", e.paramString()); } public void focusLost(FocusEvent e) { report("focusLost", e.paramString()); } }; KeyListener kl = new KeyListener() { public void keyPressed(KeyEvent e) { report("keyPressed", e.paramString()); } public void keyReleased(KeyEvent e) { report("keyReleased", e.paramString()); } public void keyTyped(KeyEvent e) { report("keyTyped", e.paramString()); } }; MouseListener ml = new MouseListener() { public void mouseClicked(MouseEvent e) { report("mouseClicked", e.paramString()); } public void mouseEntered(MouseEvent e) { report("mouseEntered", e.paramString()); } public void mouseExited(MouseEvent e) { report("mouseExited", e.paramString()); } public void mousePressed(MouseEvent e) { report("mousePressed", e.paramString()); } public void mouseReleased(MouseEvent e) { report("mouseReleased", e.paramString()); } }; MouseMotionListener mml = new MouseMotionListener() { public void mouseDragged(MouseEvent e) { report("mouseDragged", e.paramString()); } public void mouseMoved(MouseEvent e) { report("mouseMoved", e.paramString()); } }; public MyButton(Color color, String label) { super(label); setBackground(color); addFocusListener(fl); addKeyListener(kl); addMouseListener(ml); addMouseMotionListener(mml); } } public void init() { Container c = getContentPane(); c.setLayout(new GridLayout(event.length + 1, 2)); for(int i = 0; i < event.length; i++) { JTextField t = new JTextField(); t.setEditable(false); c.add(new JLabel(event[i], JLabel.RIGHT)); c.add(t); h.put(event[i], t); } c.add(b1); c.add(b2); } public static void main(String[] args) { console.run(new TrackEvent(), 700, 500); } } 另外，今天还尝试了下手工打包可执行的jar文件，可没有成功，找不到原因，郁闷。。。 本文转自Phinecos(洞庭散人)博客园博客，原文链接：http://www.cnblogs.com/phinecos/archive/2006/06/07/419356.html，如需转载请自行联系原作者
