《Java2图形设计卷II：Swing》配套光盘源码

				import javax.swing.*;
				import java.awt.*;
				
				public class OpaqueTest extends JApplet {
					public void init() {
						Container contentPane = getContentPane();
						RainPanel rainPanel = new RainPanel();
				
						ColoredPanel 	opaque = new ColoredPanel(),
										transparent = new ColoredPanel();
				
						// JComponents are opaque by default, so the opaque
						// property only needs to be set for transparent
						transparent.setOpaque(false);
				
						rainPanel.add(opaque);
						rainPanel.add(transparent);
				
						contentPane.add(rainPanel, BorderLayout.CENTER);
				
						System.out.println(opaque.isOpaque());
						System.out.println(transparent.isOpaque());
					}
				}
				class RainPanel extends JPanel {
					ImageIcon rain = new ImageIcon("rain.gif");
					private int rainw = rain.getIconWidth();
					private int rainh = rain.getIconHeight();
				
					public void paintComponent(Graphics g) {
						Dimension size = getSize();
				
						for(int row=0; row < size.height; row += rainh)
							for(int col=0; col < size.width; col += rainw)
								rain.paintIcon(this,g,col,row);
					}
				}
				class ColoredPanel extends JPanel {
					public void paintComponent(Graphics g) {
						super.paintComponent(g);
				
						Dimension size = getSize();
				
						g.setColor(Color.black);
						g.drawRect(0,0,size.width-1,size.height-1);
				
						g.setColor(Color.red);
						g.fillRect(size.width/2-25,size.height/2-25,50,50);
					}
					public Dimension getPreferredSize() {
						return new Dimension(100,100);
					}
				}