为Java的JLayeredPane组件添加窗口背景图片
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：
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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. *来自：http://blog.csdn.net/gaowen_han/article/details/8164720* 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. *
* We can use frame.pack() or frame.setSize() whatever its layout method is * (use a layout manager or not). *
* 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(). *
* Concerning the JLayeredPane, the depth 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("" + "layeredPane" + "")); 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); } }