Why is it unable to read URL through Java Applet ?

Question

I have tried to read an image with ImageIO.read(URL) in JApplet. But it failed to be initialized. Please refer to TEST.java. But if I read the image in MSDOS mode, it works. Please refer to DisplayImage.java. The only difference is Applet and MSDOS mode.
I am using WindowsXP with j2sdk1.4.1_01 installed.
//File one: TEST.java
//Please run in Applet mode
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.applet.*;
import javax.swing.*;
import javax.imageio.*;
import javax.imageio.stream.*;
import java.net.*;
public class TEST extends JApplet
     BufferedImage tempimg;
     public void init()
          try
               tempimg = ImageIO.read(new URL("http", "www.footprint.org.hk", 80, "/newsphotos/N200301270_0.jpg"));
          catch(MalformedURLException murle){}
          catch(IOException ioe){}
          JFrame f = new JFrame("ImageDisplayer");
          f.setSize(new Dimension(550,350));
          f.setVisible(true);
//End of TEST.java
//File two: DisplayImage.java
//Please run in MSDOS mode
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.applet.*;
import javax.swing.*;
import javax.imageio.*;
import javax.imageio.stream.*;
import java.net.*;
public class DisplayImage extends JApplet
     ImagePanel imagePanel;
     public static void main(String[] args) throws MalformedURLException, IOException
          DisplayImage img = new DisplayImage();
          img.init();
     public void init()
          //Display Image
          try
               imagePanel = new ImagePanel(ImageIO.read(new URL("http", "www.footprint.org.hk", 80, "/newsphotos/N200301270_0.jpg")));
          catch(MalformedURLException murle){}
          catch(IOException ioe){}
JFrame f = new JFrame("ImageDisplayer");
          f.addWindowListener(new WindowAdapter() {
               public void windowClosing(WindowEvent e) {
                    System.exit(0);
          f.getContentPane().add(imagePanel, BorderLayout.CENTER);
          f.setSize(new Dimension(550,350));
          f.setVisible(true);
class ImagePanel extends JPanel {
Image image;
public ImagePanel(Image image) {
this.image = image;
public void paintComponent(Graphics g) {
super.paintComponent(g); //paint background
//Draw image at its natural size first.
g.drawImage(image, 0, 0, this); //85x62 image
//End of DisplayImage.java

Answer 1

The security model for applets does not allow them to read from a URL unless it is on the same host the applet was loaded from. If you must do this then you must sign your applet for it to work.