自定义Popup window.

基类：采用JFrame + setUndecorated(true);

 

import java.awt.Graphics;
import java.awt.event.WindowEvent;
import java.awt.event.WindowFocusListener;

import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class PopupWindow extends JFrame
{
    public PopupWindow()
    {
        setUndecorated(true);

        // setAlwaysOnTop(true);
        addWindowFocusListener(new WindowFocusListener()
        {
            public void windowGainedFocus(WindowEvent e)
            {

            }

            public void windowLostFocus(WindowEvent e)
            {
                SwingUtilities.invokeLater(new Runnable()
                {
                    public void run()
                    {
                        setVisible(false);
                        dispose();
                    }
                });
            }
        });

    }

    public void showPopup(int x, int y)
    {
        setLocation(x, y);
        setVisible(true);
        requestFocus();
    }

    @Override
    public void paint(Graphics g)
    {
        super.paint(g);
        g.drawRect(0, 0, getWidth() - 1, getHeight() - 1);
    }
}

 通过继承PopupWindow，就可以试下模拟弹出菜单。

唯一的缺点是没有阴影，看起来没有立体感。

 

效果图：

 

 这里有模拟阴影的方法， 还没试过：

http://stackoverflow.com/questions/19105242/undecorated-jframe-shadow