Passing session info

Question

hi all,
i have lots of jsp pages and these pages use a lot of class files created by me.
i want to pass session info to class files without having to pass the info through each object that is created in the jsp pages--
what i want to know is that is there any way through which a class file a mine could fetch the session value.(i dont mind passing session info to one class-- but passing to too many classes would be a headache !!)
thanks,
gaurav

Answer 1

Not sure if this will work but worth a try.
Create a class called SessionHolder that looks something like:
public class SessionHolder {
private static HashMap sessionMap;
public synchronized static void putSession(Thread thread, HttpSession session) {
     if (sessionMap == null) { sessionMap = new HashMap(); }
     sessionMap.put(thread, session); }
public synchronized static HttpSession getSession(Thread thread) {
     return (HttpSesion)sessionMap.get(thread); }
public synchronized static void removeSession(Thread thread) {
      sessionMap.remove(thread); }
}<P>
In the servlet you store the session in the SessionHolder via:
SessionHolder.putSession(Thread.currentThread, request.getSession(true));
Always remember to remove the session from the SessionHolder when exiting the servlet or the sessions will linger and take up memory:
SessionHolder.removeSession(Thread.currentThread);
In your classes you can retrieve the session using:
HttpSession session = SessionHolder.getSession(Thread.currentThread);
This should work on the basis that the servlet container will create a new thread for each request to the servlet. As long as your classes do not create new threads they should be able to access the static hashmap to retrieve the session stored by the thread key.
Of course this is just a theory and I have not tested it out to verify if it actually works.