Java Swing - 如何创建BorderLayout并填充北，南和东位置

import java.awt.BorderLayout;

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

public class Main {
  public static void main(String[] args) {
    JFrame frame = new JFrame("test");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel(new BorderLayout());
    JPanel panel2 = new JPanel(new BorderLayout());
    panel2.add(new JButton("NORTH"), BorderLayout.NORTH);
    panel2.add(new JButton("CENTER"));
    panel.add(panel2);
    panel.add(new JButton("SOUTH"), BorderLayout.SOUTH);
    panel.add(new JButton("EAST"), BorderLayout.EAST);
    frame.add(panel);
    frame.pack();
    frame.setVisible(true);
  }
}