Java Swing - 如何向每个选项卡添加按钮

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

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

public class Main {
  public static void main(String[] args) {

    JFrame frame = new JFrame();

    JButton btn = new JButton("Test");

    JPanel panel = new JPanel();
    panel.add(btn);

    JTabbedPane tabbedPane = new JTabbedPane();
    tabbedPane.add("Tab1", panel);

    frame.add(tabbedPane, BorderLayout.CENTER);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setMinimumSize(new Dimension(300, 300));
    frame.setVisible(true);
  }
}