UIManager.put("PopupMenu.border", new LineBorder(Color.RED));
下面是测试截图:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.LineBorder;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
UIManager.put("PopupMenu.border", new LineBorder(Color.RED));
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Stuff");
menu.add(new JMenuItem("A"));
menu.add(new JMenuItem("BB"));
menu.add(new JMenuItem("CCC"));
menuBar.add(menu);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.setJMenuBar(menuBar);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}
现在,这可能不是理想的选择,因为这将影响程序中所有的弹出菜单。
更新
我研究了JMenu
及其UI代理,并发现弹出菜单是在JMenu
的一个名为ensurePopupMenuCreated
的私有方法中创建的,这可能是注入您自己的自定义代码的绝佳位置。
该方法实际上在许多不同的地方被调用,但可能getPopupMenu
是最容易访问的地方。
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.Border;
import javax.swing.border.LineBorder;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Stuff") {
private Border border = new LineBorder(Color.RED);
@Override
public JPopupMenu getPopupMenu() {
JPopupMenu menu = super.getPopupMenu();
menu.setBorder(border);
return menu;
}
};
JMenuItem mi = new JMenuItem("Help", 'H');
mi.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_H, KeyEvent.META_MASK));
menu.add(new JMenuItem("A"));
menu.add(new JMenuItem("BB"));
menu.add(new JMenuItem("CCC"));
menu.add(mi);
menuBar.add(menu);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.setJMenuBar(menuBar);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}
JMenu
应用 Border
,而不是使用一行代码或自定义类来实现它 ;) - MadProgrammersetBorder
方法:menuBar.setBorder(BorderFactory.createLineBorder(Color.BLUE, 2));
这个解决方案的优点是你可以设置厚度级别。在上面的例子中,厚度级别被设置为2。
此外,你可以在许多组件中使用setBorder来绘制各种边框,如下面的例子所示:
首先是基本代码:
主类:
import javax.swing.*;
public class Main {
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
CustomGUI sw = new CustomGUI();
sw.setVisible(true);
});
}
}
CustomGui.class:
import java.awt.*;
import javax.swing.*;
public class CustomGUI extends JFrame {
public CustomGUI() {
super("Simple example");
setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
setSize(500,500);
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
getContentPane().setBackground(Color.DARK_GRAY);
JMenuBar menuBar = new JMenuBar();
JMenu menu1 = new JMenu("menu B");
menuBar.add(menu1);
JMenuItem item = new JMenuItem("A text-only menu item");
menu1.add(item);
JMenu menu2 = new JMenu("menu B");
menuBar.add(menu2);
JMenuItem item2 = new JMenuItem("A text-only menu item");
menu2.add(item2);
add(menuBar);
}
}
现在通过添加以下行:
menuBar.setBorder(BorderFactory.createLineBorder(Color.BLUE, 2));
CustomGUI()
中,我们得到:
menu1.getPopupMenu().setBorder(BorderFactory.createLineBorder(Color.BLUE, 4));
menu2.getPopupMenu().setBorder(BorderFactory.createLineBorder(Color.BLUE, 4));
(如您所见,我没有为菜单栏设置边框,但是可以按照上述方法使用以下代码完成:
menuBar.setBorder(BorderFactory.createLineBorder(Color.BLUE, 2));
同时,我添加了另一个项目以使菜单更大且易于看到边框...)
PopupMenu.border
UIManager
е±ћжЂ§пјЊдЅ†иї™дјљеЅ±е“Ќж‰Ђжњ‰еј№е‡єиЏњеЌ•гЂ‚ - MadProgrammer