用JLayeredPane实现在不影响窗口组件布局的情况下，添加一个背景图片：
调整窗口大小后：
package com.han;
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Image;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
/**
* The JLayeredPane has no layout manager by default, so you have to use
* setBounds() for each component in it. However, you can still assign a layout
* manager to the layered pane.
* <p>
* Many programs use intermediate containers (such as panels) and their layout
* managers to lay out components on the same layer, but use absolute
* positioning to lay out components on different layers.
* <p>
* We can use frame.pack() or frame.setSize() whatever its layout method is
* (use a layout manager or not).
* <p>
* In fact, if we hesitate to use component.setPreferredSize() or
* component.setSize(), we first see the layout method employed to layout this
* component. If it has a layout manager, we use component.setPreferredSize();
* else (no layout manager), we use component.setBounds().
* <p>
* Concerning the JLayeredPane, the <i>depth</i> is higher, the component is on
* the top (of course, there are some depth conventions, like DEFAULT_LAYER,
* PALETTE_LAYER, ...). Within its depth, the position number is 0, top-most;
* -1, bottom-most; 0, 1, 2, 3, ... from top to bottom.
*
* @author HAN
*
*/
@SuppressWarnings("serial")
public class JLayeredPane_1 extends JFrame {
public JLayeredPane_1() {
// TODO Auto-generated constructor stub
Container container = getContentPane();
final JLayeredPane layeredPane = new JLayeredPane();
// layeredPane.setBorder(BorderFactory.createTitledBorder(null,
// "layeredPane", TitledBorder.LEADING, TitledBorder.TOP,
// new Font(null, Font.BOLD + Font.ITALIC, 14), Color.RED));
layeredPane.setBorder(BorderFactory.createTitledBorder("<html><b><i>" +
"<u><font face='SansSerif' size='5' color='red'>layeredPane" +
"</font></u></i></b></html>"));
Dimension dimension = new Dimension(300, 310);
layeredPane.setPreferredSize(dimension);
final JPanel panelBg = new JPanel();
final Image imageBg = Toolkit.getDefaultToolkit()
.getImage(this.getClass().getResource("/images/Lighthouse.jpg"));
ImageIcon imageIcon = new ImageIcon(imageBg.getScaledInstance
(dimension.width, dimension.height, Image.SCALE_FAST));
final JLabel bg = new JLabel(imageIcon);
final Point origin = new Point(10, 30);
final Rectangle rectangle = new Rectangle(origin, dimension);
panelBg.setBounds(rectangle);
panelBg.add(bg);
final JPanel panelContent = new JPanel();
JButton button = new JButton("button 1");
JButton button2 = new JButton("button 2");
JButton button3 = new JButton("button 3");
panelContent.setBounds(rectangle);
panelContent.setOpaque(false); // 设置为透明
panelContent.add(button);
panelContent.add(button2);
panelContent.add(button3);
layeredPane.add(panelBg, new Integer(0)); // the same to layeredPane.add(panelBg);
layeredPane.add(panelContent, new Integer(1));
container.add(layeredPane, BorderLayout.CENTER);
addComponentListener(new ComponentAdapter() {
public void componentResized(ComponentEvent e) {
// System.out.println(layeredPane.getSize()); //此处必须用getSize()而不是用getPreferredSize()
// System.out.println(layeredPane.getPreferredSize());
Dimension dimensionNew = layeredPane.getSize();
Rectangle rectangleNew = new Rectangle(origin, dimensionNew);
panelBg.setBounds(rectangleNew);
panelContent.setBounds(rectangleNew);
bg.setIcon(new ImageIcon(imageBg.getScaledInstance
(dimensionNew.width, dimensionNew.height, Image.SCALE_FAST)));
}
});
}
/**
* @param args
* @throws Exception
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
JLayeredPane_1 frame = new JLayeredPane_1();
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}