java JFrame里面怎么添加背景

我这里刚好有个例子

ImageIcon img = new ImageIcon("f:/library.jpg")//这是背景图片     

JLabel imgLabel = new JLabel(img)//将背景图放在标签里。  

this.getLayeredPane().add(imgLabel, new Integer(Integer.MIN_VALUE))//注意这里是关键，将背景标签添加到jfram的LayeredPane面板里。     

imgLabel.setBounds(0,0,img.getIconWidth(), img.getIconHeight())//设置背景标签的位置

java编写的一个表格，JTable对象加在JPanel面板上，JPanel加在JFrame上。设置背景色

public class DrawFrame {

    public static void main(String[] args) {

        final JFrame frame = new JFrame()

        frame.getContentPane().setBackground(Color.RED)

        JTable table = new JTable(4, 4) {

            @Override

            public void paint(Graphics g) {

                super.paint(g)

                Graphics2D g2d = (Graphics2D) g

                Composite com = g2d.getComposite()

                g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.1f))

                g2d.setColor(Color.RED)

                g2d.fill(new Rectangle(0, 0, this.getWidth(), getHeight()))

                g2d.setComposite(com)

                g2d.setColor(Color.BLACK)

            }

        }

        frame.getContentPane().add(table, "Center")

        frame.setVisible(true)

    }

}

Table上有一层半透明的红色层

图片也是画上去，你可以试试

import java.awt.*

import java.awt.image.*

import javax.swing.*

import javax.imageio.ImageIO

public class LoginExample {

    public static void main(final String... args) {

        EventQueue.invokeLater(new Runnable(){

                @Override public void run(){

                    try {

                        final XPanel container = new XPanel(ImageIO.read(LoginExample.class.getResource("/images/background.jpg")))

                        final JPanel panel = new JPanel()

                        final GroupLayout layout = new GroupLayout(panel)

                        container.setLayout(new BorderLayout())

                        panel.setLayout(layout)

                        panel.setOpaque(false)

                        layout.setAutoCreateGaps(true)

                        layout.setAutoCreateContainerGaps(true)

                        final JLabel name = new JLabel("用户名")

                        final JLabel pass = new JLabel("密码")

                        final JTextField name_field = new JTextField(12)

                        final JPasswordField pass_field = new JPasswordField(12)

                        name_field.setOpaque(false)

                        pass_field.setOpaque(false)

                        GroupLayout.SequentialGroup hGroup = layout.createSequentialGroup()

                        hGroup.addGroup(layout.createParallelGroup(GroupLayout.Alignment.TRAILING).

                                        addComponent(name).addComponent(pass))

                        hGroup.addGroup(layout.createParallelGroup().

                                        addComponent(name_field).addComponent(pass_field))

                        layout.setHorizontalGroup(hGroup)

                        GroupLayout.SequentialGroup vGroup = layout.createSequentialGroup()

                        vGroup.addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE).

                                        addComponent(name).addComponent(name_field))

                        vGroup.addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE).

                                        addComponent(pass).addComponent(pass_field))

                        layout.setVerticalGroup(vGroup)

                        final JFrame frame = new JFrame("Login")

                        container.add(new JLabel("**欢迎您登录**", JLabel.CENTER), BorderLayout.PAGE_START)

                        container.add(panel)

                        frame.setContentPane(container)

                        frame.pack()

                        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)

                        frame.setVisible(true)

                    } catch (Exception e) {

                    }

                }

            })

    }

    public static class XPanel extends JPanel {

        private BufferedImage background

        public XPanel(BufferedImage background) {

            this.background = background

        }

        @Override public void paintComponent(Graphics g) {

            BufferedImage bufimg = new BufferedImage(getWidth(),getHeight(), BufferedImage.TYPE_INT_ARGB)

            Graphics2D g2 = bufimg.createGraphics()

            // restore the foreground color in case the superclass needs it

            g2.setColor(g.getColor())

            super.paintComponent(g2)

            // do an alpha composite

            Graphics2D gx = (Graphics2D) g

            gx.drawImage(background,0,0,null)

            gx.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,0.8f))

            gx.drawImage(bufimg,0,0,null)

        }

    }

}

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