JAVA新手，关于BoxLayout的问题。

好像做不到吧，我只能改变他们的位置，而且不是随便改变
这是我的例子：
import java.lang.*;
import java.awt.*;
import javax.swing.*;
public class Test extends JFrame
{
private JPanel mpanel = new JPanel();
private JButton mbutton1 = new JButton("Test1");
private JButton mbutton2 = new JButton("Test2");
private JButton mbutton3 = new JButton("Test3");
private JButton mbutton4 = new JButton("Test4");
private JButton mbutton5 = new JButton("Test5");

public Test()
{
setSize(800,600);
setTitle("Test");
Init();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
show();
}
private void Init()
{
Container cp = getContentPane();
mpanel.setLayout(new BoxLayout(mpanel,BoxLayout.X_AXIS));
              /*
mbutton1.setAlignmentX(0);
mbutton2.setAlignmentX(0.25f);
mbutton3.setAlignmentX(0.5f);
mbutton4.setAlignmentX(0.75f);
mbutton5.setAlignmentX(1);
                */
mbutton1.setAlignmentY(0);
mbutton2.setAlignmentY(0.25f);
mbutton3.setAlignmentY(0.5f);
mbutton4.setAlignmentY(0.75f);
mbutton5.setAlignmentY(1);
mpanel.add(mbutton1);
mpanel.add(mbutton2);
mpanel.add(mbutton3);
mpanel.add(mbutton4);
mpanel.add(mbutton5);
cp.add(mpanel,BorderLayout.CENTER);
}
public static void main(String[] args)
{
Test test = new Test();
}
}