java - 修改 JPopupMenu/JMenuItem 外观

Question

我正在尝试创建一个具有不同颜色和圆形边框的自定义 JPopupMenu。我尝试了以下代码，但 PopupMenu 的外观没有任何变化。

JButton button = new JButton("Test");
button.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e){
        TPopupMenu popup = new TPopupMenu();
        JMenuItem item1 = new JMenuItem("Item 1");
        JMenuItem item2 = new JMenuItem("Item 2");
        popup.add(item1);
        popup.add(item2);
    }
}

自定义弹出菜单

public class TPopupMenu extends JPopupMenu{

    public TPopupMenu(){
        super();
        super.setOpaque(false);
        init();
    }
    
    private void init(){
        setBackground(Color.green);
    }
    
    @Override
    protected void paintComponent(Graphics g){
        super.paintComponent(g);
        
        g.setColor(Color.pink);
        
        int w = getWidth();
        int h = getHeight();
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTILIAS_ON);
        
        g2.fillRoundRect(0,0,w-1, h-1, 10, 10);
        g2.drawRoundRect(0,0,w-1, h-1, 10, 10);
        
        g2.setBackground(Color.red);
        g2.setColor(Color.green);
    }

}

这就是我希望我的圆形弹出菜单看起来像这样:

我是不是在我的 paintComponent 方法中做错了什么？

Answer 1

您的弹出窗口永远不可见，调用 show (Component invoker, int x, int y) 方法来显示 JPopupMenu 类。

Displays the popup menu at the position x,y in the coordinate space of the component invoker...

      JPopupMenu popup = new JPopupMenu();
      JMenuItem item = new JMenuItem("Item");
      popup.add(item);
      popup.show(frame, frame.getWidth()/2, frame.getHeight()/2);

或者您也可以调用 JPopupMenu.setVisible(boolean b) 方法。

参见 JPopupMenu#show , JPopupMenu#setVisible

---

自定义

对于圆角边框，可以使用new LineBorder(Color.black, 2, true)。 LineBorder doc

如果你想要大的自定义，我建议你使用/写一个外观。参见 tutorial|uiswing

这是我的测试:

    public class Test {
    
        private static void createAndShowGUI() {
            JFrame frame = new JFrame("HelloWorldSwing");
            frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    
            JButton button = new JButton("Test");
    
            JPopupMenu popup = new JPopupMenu();
            popup.setBorder(new LineBorder(Color.black, 2, true));
    
            {
                JMenuItem item = new JMenuItem("Cut");
                item.setForeground(Color.ORANGE);
                popup.add(item);
            }
    
            {
                JMenuItem item = new JMenuItem("Copy");
                item.setBackground(Color.RED);
                popup.add(item);
            }
    
            {
                JMenuItem item = new JMenuItem("Paste");
                popup.add(item);
            }
    
            button.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    popup.show(frame, frame.getWidth() / 2, frame.getHeight() / 2);
                    System.out.println("perfome");
                }
            });
    
            frame.getContentPane().add(button);
            frame.pack();
            frame.setVisible(true);
        }
    
        public static void main(String[] args) {
            SwingUtilities.invokeLater(new Runnable() {
                @Override
                public void run() {
                    createAndShowGUI();
                }
            });
        }
    
    }