代码：

Example9_7.java

public class Example9_7

{

public static void main(String args[]){

WindowActionEvent win= new WindowActionEvent();

PoliceListen police = new PoliceListen();//创建监视器

win.setMyCommandListener(police);

win.setBounds(100,100,460,360);

win.setTitle("处理ActionEvent事件");

}

}

WindowActionEvent.java

import java.awt.*;

import javax.swing.*;

public class WindowActionEvent extends JFrame

{

JTextField inputText;

JTextArea textShow;

JButton button;

MyCommandListener listener;

public WindowActionEvent(){

init();

setVisible(true);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

void init(){

setLayout(new FlowLayout());

inputText = new JTextField(10);

button = new JButton("确定");

textShow=new JTextArea(9,30);

add(inputText);

add(button);

add(new JScrollPane(textShow));

}

void setMyCommandListener(MyCommandListener listener){

this.listener=listener;

listener.setJTextField(inputText);

listener.setJTextArea(textShow);

inputText.addActionListener(listener);

button.addActionListener(listener);

}

}

MyCommandListener.java

import javax.swing.*;

import java.awt.event.*;

interface MyCommandListener extends ActionListener

{

public void setJTextField(JTextField text);

public void setJTextArea(JTextArea area);

}

PoliceListen.java

import java.awt.event.*;

import javax.swing.*;

public class PoliceListen implements MyCommandListener

{

JTextField textInput;

JTextArea textShow;

public void setJTextField (JTextField text){

textInput=text;

}

public void setJTextArea(JTextArea area){

textShow=area;

}

public void actionPerformed(ActionEvent e){

String str=textInput.getText();

textShow.append(str+"的长度:"+str.length()+"\n");

}

}

运行截图：