Java Swing - 如何组合FlowLayout和BoxLayout...

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;

import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class Main {
  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.setLayout(new BorderLayout());
    frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

    JPanel northPanel = new JPanel(new GridLayout(2, 1));

    JPanel welcomePanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
    welcomePanel.add(new JLabel("Welcome"));

    northPanel.add(welcomePanel);

    JPanel radioPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));

    JRadioButton button1 = new JRadioButton("Button 1", true);
    JRadioButton button2 = new JRadioButton("Button 2", false);

    ButtonGroup group = new ButtonGroup();
    group.add(button1);
    group.add(button2);

    radioPanel.add(button1);
    radioPanel.add(button2);

    northPanel.add(radioPanel);

    JPanel middlePanel = new JPanel(new GridLayout(3, 3));

    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        middlePanel.add(new JButton("Button " + i + j));
      }
    }

    JPanel southPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));

    southPanel.add(new JLabel("Whose turn:"));
    southPanel.add(new JButton("Reset"));

    frame.add(northPanel, BorderLayout.NORTH);
    frame.add(middlePanel, BorderLayout.CENTER);
    frame.add(southPanel, BorderLayout.SOUTH);

    frame.pack();
    frame.setVisible(true);
  }
}