JPanel上设置背景图片

import java.awt.*;
import javax.swing.*;
public class ImageJPanel extends JPanel{
private Image image;

public ImageJPanel(Image image){ //首先构建一个构造方法.传入的参数是Image的文件路径
  this.image=image;
  Dimension size = new Dimension(image.getWidth(null),
            image.getHeight(null));
  setSize(size);  //设置JPanel的大小为Image图象的大小
  setPreferredSize(size);
  setMaximumSize(size);
  setMinimumSize(size);
}
protected void paintComponent(Graphics g) {
  super.paintComponent(g);
  g.drawImage(image,0,0,null); //用G 把Image画出来
}
public static void main(String[]args){
  ImageJPanel imageJP = new ImageJPanel(new ImageIcon("Image/***.jpg").getImage());
  JFrame jf = new JFrame();
  jf.add(imageJP);
  jf.setSize(imageJP.getWidth(),imageJP.getHeight()+35);//这里+35 是因为JFrame上会有个标题栏 他会占35像素
  jf.setVisible(true);
}
}