【JAVA语言程序设计基础篇】--事件驱动程序设计--定义监听器的另一种方式

package chapter16;

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;

@SuppressWarnings("serial")
public class DetectSourceDemo extends JFrame{

private JButton sNew = new JButton ("Process New");
private JButton sOpen = new JButton ("Process Open");
private JButton sSave = new JButton ("Process Save");
private JButton sPrint = new JButton ("Process Print");
public DetectSourceDemo(){

setLayout(new FlowLayout());
add(sNew);
add(sOpen);
add(sSave);
add(sPrint);

sNew.addActionListener(new ButtonListener());
sOpen.addActionListener(new ButtonListener());
sSave.addActionListener(new ButtonListener());
sPrint.addActionListener(new ButtonListener());

}
public static void main(String[] args) {
JFrame frame = new DetectSourceDemo();
frame.setTitle("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.pack();
frame.setVisible(true);
}
class ButtonListener implements ActionListener{

@Override
public void actionPerformed(ActionEvent e) {
if(e.getSource()==sNew){
System.out.println("new");
}
else if(e.getSource()==sOpen){
System.out.println("open");
}
else if(e.getSource()==sSave){
System.out.println("save");
}
else {
System.out.println("print");
}
}
}
}

/**
* 这种方法不是很好，因为将太多的责任放在了一个类中，最好能设计一个监听类 ，只负责处理事件，这种设计会让代码易于阅读和维护
*/

package chapter16;

import javax.swing.*;

import java.awt.event.*;

@SuppressWarnings("serial")
public class FrameAsListenerDemo extends JFrame
implements ActionListener {
// Create four buttons
private JButton jbtNew = new JButton("New");
private JButton jbtOpen = new JButton("Open");
private JButton jbtSave = new JButton("Save");
private JButton jbtPrint = new JButton("Print");

public FrameAsListenerDemo() {
// Create a panel to hold buttons
JPanel panel = new JPanel();
panel.add(jbtNew);
panel.add(jbtOpen);
panel.add(jbtSave);
panel.add(jbtPrint);

add(panel);

// Register listener with buttons
jbtNew.addActionListener(this);
jbtOpen.addActionListener(this);
jbtSave.addActionListener(this);
jbtPrint.addActionListener(this);
}

/** Implement actionPerformed */
public void actionPerformed(ActionEvent e) {
if (e.getSource() == jbtNew)
System.out.println("Process New");
else if (e.getSource() == jbtOpen)
System.out.println("Process Open");
else if (e.getSource() == jbtSave)
System.out.println("Process Save");
else if (e.getSource() == jbtPrint)
System.out.println("Process Print");
}

/** Main method */
public static void main(String[] args) {
JFrame frame = new FrameAsListenerDemo();
frame.setTitle("FrameAsListenerDemo");
frame.setLocationRelativeTo(null); // Center the frame
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
}