Java Swing - 如何使用BorderLayout在JPanel中布局组件

import java.awt.BorderLayout;
import java.awt.Dimension;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Main {
  public static void main(String[] args) {
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.getContentPane().add(getPanel());
    f.pack();
    f.setVisible(true);
  }

  private static JPanel getPanel() {
    JPanel panel = new JPanel(new BorderLayout());
    panel.add(new JLabel("Top"), BorderLayout.NORTH);
    panel.add(new JLabel("Center"), BorderLayout.CENTER);
    panel.add(new JLabel("Bottom"), BorderLayout.SOUTH);
    panel.setPreferredSize(new Dimension(400, 300));
    return panel;
  }
}