import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
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.border.EmptyBorder;
public class Main {
public static void main(String[] args) {
JFrame frame = new JFrame();
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.setVisible(true);
}
}
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();
}
}
【jframe】
