如何围绕JPanel扩展JFrame？

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class MyFrame extends JFrame {
    private JPanel panel;

    public MyFrame() {
        setTitle("My Frame");
        setSize(400, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        panel = new JPanel();
        setContentPane(panel);

        JButton button = new JButton("Click me");
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                // 处理按钮点击事件
            }
        });

        panel.add(button);
    }

    public static void main(String[] args) {
        MyFrame frame = new MyFrame();
        frame.setVisible(true);
    }
}