Writing to a file from a web app in tomcat

[Alex O'Ree]

I'm using the following code to read a file in META-INF
  URL prop = application.getResource("/META-INF/config.properties");
        if (prop == null) {
            throw new Exception("Cannot locate the configuration file.");
        }
        session = _session;
        propertiesurl = prop;
        InputStream in = prop.openStream();
        Properties p = new Properties();
        p.load(in);
        in.close();

This works in both tomcat and jboss.

Then later one, I want to be able to save the changes. Using code
similar to this

FileOutputStream fos = new FileOutputStream(new File(propertiesurl.toString()));
        String msg="Edited at " + System.currentTimeMillis() + " by "
+ request.getRemoteUser();
             p.store(fos, msg);
        fos.close();

The propertiesurl.toString() method in tomcat returns a JNDI URL,
which cannot be used using the file io api's. In Jboss, this code
works just fine. Application.getResource returns a file:/// url.

So the question is, how can get the same type of setup in Tomcat?
(write to a file in META-INF)