JAVA 设置背景图片

关键就就是这几句话

ImageIcon image = new ImageIcon(Main.class.getResource("back.png"));

Image ii=image.getImage();

g.drawImage(ii, 0,0, this.getWidth(), this.getHeight(), null);

package open.ui;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;

import javax.swing.ImageIcon;
import javax.swing.JFrame;

public class Main extends JFrame{
ImageIcon image = new ImageIcon(Main.class.getResource("back.png"));
public Image ii=image.getImage();

public static void main(String[] args) {
Main g = new Main();
g.setSize(900,800);
g.setVisible(true);
}
public void paint(Graphics g){
Color c = g.getColor();
g.fillOval(100, 100, 50, 50);
g.drawImage(ii, 0,0, this.getWidth(), this.getHeight(), null);
}

}