java awt 页面布局

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

//<applet code="CardLayoutDemo" width=300 height=100></applet>

public class CardLayoutDemo extends Applet implements ItemListener
{
String msg="";
Checkbox winXP,win7,solaris,mac;
//Panel osCards;
//CardLayout cardLO;
//Button Win,Other;

public void init()
{
/*
Win=new Button("Windows");
Other=new Button("Other");
add(Win);
add(Other);

cardLO=new CardLayout();
osCards=new Panel();
osCards.setLayout(cardLO);
*/
GridBagLayout gbag=new GridBagLayout();
GridBagConstraints gbc=new GridBagConstraints();
setLayout(gbag);

winXP=new Checkbox("Windows XP",null,true);
win7=new Checkbox("Windows 7");
solaris=new Checkbox("Solaris");
mac=new Checkbox("Mac OS");

/*
Panel winPan=new Panel();
winPan.add(winXP);
winPan.add(win7);

Panel otherPan=new Panel();
otherPan.add(solaris);
otherPan.add(mac);

osCards.add(winPan,"Windows");
osCards.add(otherPan,"Other");
add(osCards);

Win.addActionListener(this);
Other.addActionListener(this);

addMouseListener(this);
*/

gbc.weightx=1.0;
gbc.ipadx=200;
gbc.insets=new Insets(4,4,0,0);

gbc.anchor=GridBagConstraints.NORTHEAST;
gbc.gridwidth=GridBagConstraints.RELATIVE;
gbag.setConstraints(winXP,gbc);

gbc.gridwidth=GridBagConstraints.REMAINDER;
gbag.setConstraints(win7,gbc);

gbc.weighty=1.0;
gbc.gridwidth=GridBagConstraints.RELATIVE;
gbag.setConstraints(solaris,gbc);

gbc.gridwidth=GridBagConstraints.REMAINDER;
gbag.setConstraints(mac,gbc);

add(winXP);
add(win7);
add(solaris);
add(mac);
winXP.addItemListener(this);
win7.addItemListener(this);
solaris.addItemListener(this);
mac.addItemListener(this);
}
public void itemStateChanged(ItemEvent ie)
{
repaint();
}
/*

public void mousePressed(MouseEvent me)
{
cardLO.next(osCards);
}

public void mouseClicked(MouseEvent me){}
public void mouseEntered(MouseEvent me){}
public void mouseExited(MouseEvent me){}
public void mouseReleased(MouseEvent me){}
public void actionPerformed(ActionEvent ae)
{
if(ae.getSource()==Win)
{
cardLO.show(osCards,"Windows");
}
else
{
cardLO.show(osCards,"Other");
}
}
*/

public void paint(Graphics g)
{
msg="Current state: ";
g.drawString(msg,6,80);
msg="windows xp: "+winXP.getState();
g.drawString(msg,6,100);
msg="window 7:"+win7.getState();
g.drawString(msg,6,120);
msg="solaris: "+solaris.getState();
g.drawString(msg,6,140);
msg="mac: "+mac.getState();
g.drawString(msg,6,160);
}
}