Java如何在布局中添加图像作为背景

Question

我有一个使用 CardLayout 的类，它有两张带有按钮的卡片。我希望能够做的是放置一个像背景一样的图像，例如 Windows 中的桌面背景。该程序最终将有几张不同的卡片，我希望能够在每张卡片上放置不同的背景。我已经尝试过在此站点上其他类似问题中提出的许多建议以及通过谷歌搜索可以找到的任何建议，但我似乎无法让它发挥作用。我知道使用 CardLayout 我不能将面板放在面板顶部，因此将图像放在 JPanel 上是行不通的。所以我的问题是，根据下面发布的代码，是否有更好的方法来设置我的布局以使其更好地工作，而且我应该如何显示图像以使其位于按钮的背景中？任何帮助将不胜感激。

import java.awt.*;
import java.awt.event.*;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.*;

public class Cards implements ActionListener {    
private JPanel cards;
private JButton button1;
private JButton button2;
private Image backgroundImage;

public void addComponentToPane(Container pane) throws IOException {
    backgroundImage = ImageIO.read(new File("background.jpg"));

    //create cards
    JPanel card1 = new JPanel()
    {
        @Override
        public void paintComponent(Graphics g)
        {
            g.drawImage(backgroundImage, 0, 0, null);
        }
    };
    JPanel card2 = new JPanel();
    button1 = new JButton("Button 1");
    button2 = new JButton("Button 2");
    button1.addActionListener(this);
    button2.addActionListener(this);        
    card1.add(button1);        
    card2.add(button2);
    //create panel that contains cards
    cards = new JPanel(new CardLayout());
    cards.add(card1, "Card 1");
    cards.add(card2, "Card 2");
    pane.add(cards, BorderLayout.SOUTH);        
}

public void itemStateChanged(ItemEvent evt) {
    CardLayout cl = (CardLayout)(cards.getLayout());
    cl.show(cards, (String)evt.getItem());
}

public static void createAndShowGUI() throws IOException {
    //create and setup window
    JFrame frame = new JFrame("Frame"); 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        
    //create and setup content pane
    Cards main = new Cards();
    main.addComponentToPane(frame.getContentPane());        
    //display window
    frame.pack();
    frame.setSize(800, 600);
    frame.setResizable(false);
    frame.setVisible(true);
}

public void actionPerformed(ActionEvent ae) {
    if (ae.getSource() == button1) {
        CardLayout cl = (CardLayout) (cards.getLayout());
        cl.show(cards, "Card 2");     
    } else if (ae.getSource() == button2) {
        CardLayout cl = (CardLayout) (cards.getLayout());
        cl.show(cards, "Card 1");
    }        
}            

public static void main(String[] args) {
    //set look and feel
    try {
        UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
    } catch (UnsupportedLookAndFeelException ex) {
        ex.printStackTrace();
    } catch (IllegalAccessException ex) {
        ex.printStackTrace();
    } catch (InstantiationException ex) {
        ex.printStackTrace();
    } catch (ClassNotFoundException ex) {
        ex.printStackTrace();
    }                

    //schedule job for the event dispatch thread creating and showing GUI        
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {                
                try {
                    createAndShowGUI();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

        }
    });     
}   
}

Answer 1

您需要覆盖方法paintComponent(Graphics g)的 JPanel并使用 drawImage()在 Graphics 上对象 g 如 this example .

---

此外，通过 @trashgod 检查这两个示例:

1. example .
2. example .