Best way to open new browser window - HTTP request in java or webpage

I have a web page that based upon the users actions, submits a request to a servelet. The servelet uses a properties file and what the user selected to build a url. I need to now open a new browser tab / window using that url. I could perform these actions on the web page, but I'm not sure which is best or exactly how to do it in java.

I've learned about using URLConnection, but I'm not sure what to return so that the new page is opened. The Url is to a page from a different app running on a different server.

You can't force a new window to open from the server. You need to do it on the client when the request is made.

Thanks - that answers that question, so now I need to figure out how to feed my velocity values into javascript so that I can build the url and open my new window. I know js, but am new to velocity

Yes, that's right. Just a hint: first design the Javascript you want to see, then figure out how to produce that Javascript. I know that might sound obvious but it's amazing (based on the posts I see here) how many people don't do it that way.