import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Graphics;
import java.awt.BorderLayout;
import java.awt.Dimension;
import javax.swing.ImageIcon;
 
public class ImagenFondo extends JFrame{
 
	public static void main(String args[]){
		ImagenFondo imagenFondo = new ImagenFondo();
		imagenFondo.setSize(500,400);
		imagenFondo.setVisible(true);
		imagenFondo.setLocationRelativeTo(null);
	}
 
    public ImagenFondo() {
    	PanelFondo panelFondo = new PanelFondo();
    	this.add(panelFondo,BorderLayout.CENTER);
    	this.pack();
    }
 
}
 
class PanelFondo extends JPanel {
 
	public PanelFondo(){
		this.setSize(100,100);
	}
 
	public void paintComponent(Graphics g){
		Dimension tamanio = getSize();
		ImageIcon imagenFondo = new ImageIcon(getClass().getResource("marzo2010.jpg"));
		g.drawImage(imagenFondo.getImage(), 0, 0, tamanio.width,(int)tamanio.height, null);
		setOpaque(false);
		super.paintComponent(g);
	}
}