在Java Swing编程中，程序员还可以自定义对话框，一般可以从JDialog类来继承。下面给出一个对话框类的代码：
class HelpAbout extends JDialog implements ActionListener
{
JavaWord mainFrame;
JButton okButton;
javax.swing.Timer myTimer;
int Counter=0;
public HelpAbout(JavaWord mainFrame)
{
super(mainFrame,"关于本程序的说明",true); //true 代表为有模式对话框
this.mainFrame= mainFrame;
JPanel contentPanel=new JPanel();
contentPanel.setLayout(new BorderLayout());
JLabel imageLabel=new JLabel(new ImageIcon(".\\images\\javalogo.gif"));
contentPanel.add(imageLabel,BorderLayout.WEST);
JPanel authorInfoPane=new JPanel();
authorInfoPane.setLayout(new GridLayout(1,1));
JTextArea aboutContent=new JTextArea("本程序是作者在学习Java2 Swing编程的一个简单的程序，\n并不作为商业目的使用。");
aboutContent.enable(false);
authorInfoPane.add(aboutContent);
contentPanel.add(authorInfoPane,BorderLayout.NORTH);
JPanel sysInfoPane=new JPanel();
sysInfoPane.setLayout(new GridLayout(5,1));
sysInfoPane.setBorder(BorderFactory.createLoweredBevelBorder());
contentPanel.add(sysInfoPane,BorderLayout.CENTER);
JLabel userName=new JLabel("本机的用户名为："+System.getProperty("user.name"));
JLabel osName=new JLabel("本机的操作系统是："+System.getProperty("os.name"));
JLabel javaVersion=new JLabel("本机中所安装的Java SDK的版本号是："+System.getProperty("java.version"));
JLabel totalMemory=new JLabel("本机中Java虚拟机所可能使用的总内存数："+Runtime.getRuntime().totalMemory()+"字节数" );
JLabel freeMemory=new JLabel("本机中Java虚拟机所剩余的内存数?quot;+Runtime.getRuntime().freeMemory()+"字节数" );
sysInfoPane.add(userName);
sysInfoPane.add(osName);
sysInfoPane.add(javaVersion);
sysInfoPane.add(totalMemory);
sysInfoPane.add(freeMemory);
JPanel OKPane=new JPanel();
okButton=new JButton("确定（O）",new ImageIcon(".\\images\\ok.gif"));
okButton.setMnemonic('O'); //设置快捷键为"Alt + O"
/*以下代码是设置案钮的Rollover图象*/
Icon rollover = new ImageIcon(".\\images\\exit.gif");
Icon general = new ImageIcon(".\\images\\ok.gif");
Icon press = new ImageIcon(".\\images\\help.gif");
okButton.setRolloverEnabled(true);
okButton.setIcon(general); //设置离开时的图象
okButton.setRolloverIcon(rollover); //设置在按纽上时的图象
okButton.setPressedIcon(press); //设置在按下按纽时的图象
this.getRootPane().setDefaultButton(okButton); //设置该按钮为该对话框的默认的按钮?.
okButton.addActionListener(this);
OKPane.add(okButton);
contentPanel.add("South",OKPane);
setContentPane(contentPanel);
// this.setResizable(false); //设置对话框为不可改变大小
myTimer=new javax.swing.Timer(1000,this);
myTimer.start();
}
public void actionPerformed(ActionEvent parm1)
{
// TODO: Add your code here
if(parm1.getSource()==okButton)
{
dispose();
}
else if(parm1.getSource()==myTimer)
{
Counter++;
this.setTitle("当前的定时器的值为:"+Counter+"秒");
}
}
}
在事件响应代码中显示出该对话框，其程序代码如下：
HelpAbout aboutDialog=new HelpAbout(this);
aboutDialog.setSize(500,500);
aboutDialog.show();
