java.security.AccessControlException: File accessible thru browser but not within same server

Question

So to not repeat myself too much, please refer to serve static image along side java google-enpoint api.

As you can see from the referenced link, I am able to view the image through the url. However, when I am trying to read filenames using similar code to

public void listFilesForFolder(final File folder) {
    for (final File fileEntry : folder.listFiles()) {
        if (fileEntry.isDirectory()) {
            listFilesForFolder(fileEntry);
        } else {
            System.out.println(fileEntry.getName());
        }
    }
}

final File folder = new File("/home/you/Desktop");
listFilesForFolder(folder);

I get a security exception

java.security.AccessControlException: access denied ("java.io.FilePermission" "/myImages" "read")

Does anyone know the fix? How come the call thru the browser show the image and yet a call from within the server itself throws an exception? I find that strange.

Answer 1

If you've configured a file as a "static" resource, it'll be served up by a separate pool of servers that are optimized for serving static content. A consequence is that the file isn't available to be opened from your app. "resource" files are available for the app to open and read.

That's documented here.

You'll need to use a relative path when opening a resource. You've shown an absolute path above.

Answer 2

If the server is running as a service, make sure that service has permissions to the folder and files you're trying to read.