java添加背景图片代码

以下是在Java Swing中添加背景图片的代码示例：

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class BackgroundImage extends JPanel {

  private Image backgroundImage;

  public BackgroundImage(String fileName) throws IOException {
    backgroundImage = ImageIO.read(new File(fileName));
  }

  @Override
  public Dimension getPreferredSize() {
    return new Dimension(backgroundImage.getWidth(null), backgroundImage.getHeight(null));
  }

  @Override
  protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.drawImage(backgroundImage, 0, 0, null);
  }
  
  public static void main(String[] args) {
    JFrame frame = new JFrame("Background Image Example");
    try {
      frame.setContentPane(new BackgroundImage("background.jpg"));
    } catch (IOException e) {
      e.printStackTrace();
    }
    frame.pack();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
}

请注意，上面的示例假设你已经有了一张名为 "background.jpg" 的图片文件，并将其放在了与Java文件相同的目录下。如果你有不同的文件名或路径，请相应地更改 `BackgroundImage` 构造函数中的参数。