Determinar redireccionamiento de URL's (redirects)

Un ejemplo básico para determinar si un determinado URL redirecciona a otra dirección.
La función de esta clase obtiene el código de respuesta de la conexión HTTP y si es cualquiera de los códigos de redireccionamiento: 301/302/303, obtiene la dirección redireccionada del encabezado "Location".

import java.net.HttpURLConnection;
import java.net.URL;

public class URLUtils {

   /**
   * Prints the redirect URL for the provided input URL (if it applies).
   * @param url
   */
   public static void printRedirect(String url) {
      try {
         URL urlToPing = new URL(url);
         HttpURLConnection urlConn = (HttpURLConnection) urlToPing
          .openConnection();
        // Needed to check if it is a redirect.
        urlConn.setInstanceFollowRedirects(false);

       // It's any of these response codes: 301/302/303
       if(urlConn.getResponseCode() == HttpURLConnection.HTTP_MOVED_PERM
          || urlConn.getResponseCode() == HttpURLConnection.HTTP_MOVED_TEMP
          || urlConn.getResponseCode() == HttpURLConnection.HTTP_SEE_OTHER) {
         System.out.println("URL <" + url + "> redirects to: <"
            + urlConn.getHeaderField("Location") + ">, Response Code: " +
            + urlConn.getResponseCode());
       }else {
         System.out.println("URL <" + url + "> has no redirect, Response   Code:  "
   + urlConn.getResponseCode());
       }
     } catch(Exception e) {
      e.printStackTrace();
     }
   }

   public static void main(String[] args) {
      URLUtils.printRedirect("http://www.google.com");
      URLUtils.printRedirect("http://www.crjug.org");
   }
}

Salida:

URL <http://www.google.com> redirects to: <http://www.google.co.cr/>, Response Code: 302
URL <http://www.crjug.org> has no redirect, Response Code: 200