AccessControlException in Applet

Question

I've been searching the web for some time now to a sollution to my problem, but none of the suggestions I've seen have worked, so here I am. I'm currently taking a Java programming class in which we are programming applets. I've written a perfectly functioning applet that draws ImageIcons made from .jpg and .png files that are located in the same directory as the .java and .class files for my applet. The applet compiles and executes beautifully when run through my java editor (TextPad). The problem comes when I embed the applet in an HTML document (which is also located in the same directory) and try to open the HTML (using IE 6) I get the following error visible in my Sun Java Console:
java.security.AccessControlException: access denied (java.io.FilePermission selectupleft.png read)
I have tried other applets, and they work fine as long as they do not read any files into ImageIcons. I've seen numerous posts concerning this error and most suggestions involve modifying the .policy file, which I have tried multiple times but to no avail. Also, I need to be able to upload my HTML file and applet .class files onto a server so they can be viewed remotely. When I do this (and also upload the .png files to the same place) and try to view the HTML file, I get the same error as when I try to view it locally.
Basically, my question is: is modifying the .policy file the only way to make this work? How can I do this so that the applet is allowed to read from files that are in the same directory on the server as the applet is? Any help would be greatly appreciated, thanks.

Answer 1

For very good security reasons unsigned applets are not permitted to acess files on the client machine. You can't access files but you can access data from the server that delivered the applet.
The best way to cope with icons it to put the icons on the server with the .class files, and then access it as a "resource". Resources are files accessed via the ClassLoader which loads your classes. Resources really are worth getting your head arround. Any file which is like part of the program, properties files, xml configuration files and images are good as resources.
The resource mechanism gets files from wherever it gets the .class files, whether they are in a .jar file, accessed over the net or both.
Here's the code I'm using:
     * Load an image icon from a resource
     * @param name The name of the resource
     * @param alt Alternative and mouseover text for icon
     * @return The ImageIcon for display
    static ImageIcon createImageIcon(String name, String alt) {
        URL url = FgApplet.class.getResource(name + ".png");
        if(url == null)
            throw new IllegalArgumentException("No such image as " + name);
        return new ImageIcon(url, alt);
    }(FgApplet is the name of the class the code is in. In general you could use any class name whose class file is in the same place as the .png file).