import java.io.*;
import java.net.*;

public class URLbug {
    URL u;
    URLConnection urlc;

    public static void main(String args[]) {
       URLbug ub = new URLbug();
    }

    public URLbug() {
       try{
        int len;
        u = new URL("file:/net/java3d/export/java3d/builds/daily/README");
        urlc = u.openConnection();
        urlc.connect();
        // uncomment to see workaround
        // urlc.getContentType();
        len = urlc.getContentLength();
        if (len<0) {
            System.out.println(len+"not a valid length");
        } else {
            System.out.println(len+"bytes");
        }
       } catch (IOException ioe) { ioe.printStackTrace(); }

    }

}

This doesn't seem to affect http protocol urls.