java - 未修饰的 JFrame 阴影

Question

如何给未修饰的 jframe 添加阴影？

根据我在网上找到的信息，您可以将 jframe 添加到另一个黑色半透明窗口以产生阴影效果。或者以某种方式将类似的东西应用于 JFrame:

    Border loweredBorder = new EtchedBorder(EtchedBorder.LOWERED);
    setBorder(loweredBorder);

无论哪种方式，我只想知道最好的方法，或者可能是一种完全不同的方式来获得相同的效果，比如从另一个类而不是 jframe 扩展。我是 Java 的新手，所以我可能会走错方向，因此不胜感激任何建议。

Answer 1

基本上，您需要制作一系列图层。

• JFrame
• 阴影面板
• 和内容...

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;

public class ShadowWindow {

    public static void main(String[] args) {
        new ShadowWindow();
    }

    public ShadowWindow() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setUndecorated(true);
                frame.setBackground(new Color(0, 0, 0, 0));
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setContentPane(new ShadowPane());

                JPanel panel = new JPanel(new GridBagLayout());
                panel.add(new JLabel("Look ma, no hands"));

                frame.add(panel);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class ShadowPane extends JPanel {

        public ShadowPane() {
            setLayout(new BorderLayout());
            setOpaque(false);
            setBackground(Color.BLACK);
            setBorder(new EmptyBorder(0, 0, 10, 10));
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
            g2d.fillRect(10, 10, getWidth(), getHeight());
            g2d.dispose();
        }
    }
}