怎么区分关闭窗口前 焦点 是在非模态的JDialog还是在父窗口

在非模态的JDialog和父窗口之间区分焦点的方法是通过调用`KeyboardFocusManager`类的`getFocusedWindow()`方法来获取当前焦点所在的窗口。然后，可以使用`instanceof`关键字来判断焦点所在的窗口是非模态的JDialog还是父窗口。以下是一个示例代码：

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;

public class FocusExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Focus Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 200);

        JButton button = new JButton("Open Dialog");
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                JDialog dialog = new JDialog(frame, "Dialog", false);
                dialog.setSize(200, 100);
                dialog.setLocationRelativeTo(frame);
                dialog.setVisible(true);
            }
        });

        frame.getContentPane().add(button);
        frame.setVisible(true);
        
        KeyboardFocusManager focusManager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
        Window activeWindow = focusManager.getFocusedWindow();
        if (activeWindow instanceof JDialog) {
            System.out.println("焦点在非模态的JDialog上");
        } else if (activeWindow == frame) {
            System.out.println("焦点在父窗口上");
        }
    }
}

运行以上代码，当点击"Open Dialog"按钮打开一个JDialog时，将会根据焦点所在的窗口进行输出。