JInternalFrame动态显示和隐藏标题栏

import javax.swing.*;
import javax.swing.plaf.basic.BasicInternalFrameUI;
import java.awt.*;

public class MainFrame extends JFrame {
    private JDesktopPane desktopPane;

    public MainFrame() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(800, 600);

        desktopPane = new JDesktopPane();
        add(desktopPane);

        JInternalFrame internalFrame = new JInternalFrame("Internal Frame", true, true, true, true);
        internalFrame.setSize(200, 200);
        internalFrame.setLocation(100, 100);

        // 获取JInternalFrame的UI对象
        BasicInternalFrameUI ui = (BasicInternalFrameUI) internalFrame.getUI();

        // 创建新的UI对象，并重写createNorthPane()方法
        BasicInternalFrameUI newUI = new BasicInternalFrameUI(internalFrame) {
            @Override
            protected JComponent createNorthPane(JInternalFrame frame) {
                // 控制标题栏的显示和隐藏
                if (frame.isShowing()) {
                    return super.createNorthPane(frame);
                } else {
                    return null;
                }
            }
        };

        // 将新的UI对象设置给JInternalFrame
        internalFrame.setUI(newUI);

        desktopPane.add(internalFrame);
        internalFrame.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            MainFrame frame = new MainFrame();
            frame.setVisible(true);
        });
    }
}