Java servlet session - how to test for a valid session in a servlet

When you're writing Java web applications -- for example, an application like a discussion forum -- you end up writing Java servlets where you need to know if the user accessing your servlet has a valid Java servlet session established. If they have a valid servlet session established, you might do one thing in your servlet code, but if they don't have a valid servlet session, you might handle their request differently.

How to put an object on the request in a servlet

Many times when you're working with Java servlets and JSP's, you'll want to forward some piece of information from your servlet to your JSP without having to put that piece of information into the session. For instance, in many applications you may not have a user session, and in other cases where you do have a session, you may just not want to put a bunch of junk in there.

Java servlet example - HttpServletRequest, getPathInfo, and getRequestURI

Working on tag support for this blog, I've cut a little sample code out of a Java servlet, and I'm showing it below. I was looking at the HttpServletRequest, and was curious about the difference between request.getPathInfo(), request.getPathTranslated(), and request.getRequestURI(), so I created this demo code. Here's the example code from the servlet: