Attaching a map retrieved from request.getParameterMap to the session scope
Posted on 2004-10-04
We use a content management system that allows custom functionality via JSPs/servlets. When you call a servlet or JSP from the content management system, it's POSTs a bunch of proprietary parameters that you can use in the custom functionality.
I am calling a servlet and using the request.getParameterMap() method to get a map of the keys and values (parameters) POSTed from the content management system. Then I attach this map to the HttpSession and forward to a JSP. From that JSP, the user can do some stuff, and then submit the form on the JSP, which goes to the servlet again, which does some more processing and then forwards back to the JSP.
After I submit the JSP the 2nd time, I lose all the keys and values (entries) in my map object in the session. I think this is because they're just references to something that doesn't exist anymore.
I will write out the steps involved and show you where it fails:
1 - Call servlet from the content management system. A session already exists.
2 - The servlet uses the getParameterMap method to get a map object and then attaches it the existing session. Then it forwards to a JSP.
3 - The JSP does stuff. I can iterate through the map object attached to the session and see all my keys and values.
4 - If I submit the JSP, it goes to the servlet, which has IF logic NOT to add the parametermap to the session. I only want to do this the first time the servlet is accessed (called by the content management system). Then it forwards to the JSP again.
5 - Here's where I am stuck. Now if I try to access keys or values from the map, I can see that there are none. The map object no longer has any entries.