code: private String getRealm(String sUrl) throws IOException, ModuleException
     {
  
        AuthorizationHandler ah = AuthorizationInfo.getAuthHandler();
  
        try
        {
           URL url = new URL(sUrl);
           HTTPConnection connection = new HTTPConnection(url);
           connection.removeModule(CookieModule.class);
           AuthorizationInfo.setAuthHandler(null);
  
           HTTPResponse resp = connection.Get(url.getFile());
  
           String authHeader = resp.getHeader("WWW-Authenticate");
           if (authHeader == null)
           {
              return null;
           }
  
           String realm = authHeader.split("=")[1];
           realm = realm.substring(1, realm.length() - 1);
  
           return realm;
  
        }
        finally
        {
           AuthorizationInfo.setAuthHandler(ah);
        }
     }
docs: Get realm by URL.
  
  @param sUrl URL string.
  @return realm name or null.
  @throws IOException transport exception.
  @throws ModuleException ModuleException.