Swing 带标题栏的右键菜单（三）增强版

     这里主要通过PopupFactory来实现对菜单或右键弹出菜单添加标题，而不用从写JPopupMenu 或JMenu 。

效果如下图：

右键菜单：

 

JMenu:

import java.awt.*;import java.awt.event.MouseEvent;import java.awt.geom.AffineTransform;import java.awt.image.BufferedImage;import javax.swing.*;public class TitlePopupMenuFactory extends PopupFactory {    private static final int POPUP_TITLE_WIDTH = 30;    private Font             font              = new Font("Dialog", Font.BOLD,                                                       13);    @Override    public Popup getPopup(Component owner, Component contents, int x, int y)            throws IllegalArgumentException {        if (contents instanceof JPopupMenu || contents instanceof JMenu) {            Dimension dim = contents.getPreferredSize();            dim.width += POPUP_TITLE_WIDTH;            ((JComponent) contents).setBorder(null);            JComponent comp = new JPanel();            comp.setBorder(UIManager.getBorder("PopupMenu.border"));            comp.setPreferredSize(dim);            comp.setLayout(new BorderLayout());            comp.add(contents, BorderLayout.CENTER);            comp.add(new JLabel(createImage("Menu Title", dim.height)),                    BorderLayout.WEST);            return super.getPopup(owner, comp, x, y);        }        return super.getPopup(owner, contents, x, y);    }    private ImageIcon createImage(String text, int height) {        BufferedImage bi = new BufferedImage(POPUP_TITLE_WIDTH, height,                BufferedImage.TYPE_INT_ARGB);        ImageIcon image = new ImageIcon(bi);        Graphics2D g2d = bi.createGraphics();        GradientPaint paint = new GradientPaint(0, 0, Color.yellow,                POPUP_TITLE_WIDTH, 10, Color.red, true);        g2d.setPaint(paint);        g2d.fillRect(0, 0, bi.getWidth(), bi.getHeight());        AffineTransform at = new AffineTransform();        at.rotate(-Math.PI / 2);                g2d.setTransform(at);        g2d.setColor(Color.black);        g2d.setFont(font);                int stringWidth = g2d.getFontMetrics().stringWidth(text);        g2d.drawString(text, -(height + stringWidth) / 2, bi.getWidth() / 2);        return image;    }    //test    public static void main(String[] args) {        PopupFactory.setSharedInstance(new TitlePopupMenuFactory());        final JFrame frame = new JFrame();        frame.setSize(600, 500);        frame.setTitle("ImageMenu");        JMenu jmenu = new JMenu("Menu");        jmenu.add(new JMenuItem("MenuItem1"));        jmenu.add(new JMenuItem("MenuItem2"));        jmenu.add(new JMenuItem("MenuItem3"));        jmenu.add(new JMenuItem("MenuItem4"));        JMenuBar menuBar = new JMenuBar();        menuBar.add(jmenu);        frame.setJMenuBar(menuBar);        final JPopupMenu menu = new JPopupMenu("Windows XP Perfessional");        menu.add(new JMenuItem("Winzip 8.0"));        menu.addSeparator();        menu.add(new JMenuItem("Programs"));        menu.addSeparator();        menu.add(new JMenuItem("Shut Down..."));        JLabel label = new JLabel("Right click me to show image popup menu.");        label.addMouseListener(new java.awt.event.MouseAdapter() {            public void mouseReleased(MouseEvent e) {                if (e.isPopupTrigger()) {                    menu.show(frame, e.getPoint().x, e.getPoint().y);                }            }        });        frame.getContentPane().add(label, BorderLayout.CENTER);        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        frame.setVisible(true);    }}