This week's book giveaways are in the Refactoring and Agile forums. We're giving away four copies each of Re-engineering Legacy Software and Docker in Action and have the authors on-line! See this thread and this one for details.
The request dispatcher can only be used for urls internal to your web application/server
If the url you are wanting to access is a completely different url again, you probably want to look at a response.redirect.