Getting a JSP servlet session, returns a null value

Question

I am using jsp/servlets for a basic ajax application. I am setting a session with a servlet, but i am getting a null returned. My code snippets as follow:

Servlet:

protected void doPost(HttpServletRequest request, HttpServletResponse response)         throws  ServletException, IOException {

    String name=null;
    String sessionStrSet = null;


    if(request.getParameter("session").toString().equals("setSession")){

         name = request.getParameter("user");

         HttpSession session = request.getSession(true);
         session.setAttribute("sessionPw", name);
         sessionStrSet = session.getAttribute("sessionPw").toString();

         response.setContentType("text/plain");  
         response.setCharacterEncoding("UTF-8"); 
         response.getWriter().write(sessionStrSet + " " + "data write");

    }

    if(request.getParameter("session").toString().equals("getSession")){
        //how do i retrieve the session data here?
        response.setContentType("text/plain");  
        response.setCharacterEncoding("UTF-8"); 
        response.getWriter().write(sessionStrSet + "get session");
    }


}

The ajax works fine it is just the session retrieving that seems to be an issue. I can pull the data once its been set in the first if(). But when I do another post request it comes back as null. Do I need another HttpSession? Any help much appreciated, I am a PHP dev not JSP so its very new to me!

In the second if block, which is mutually exclusive from the first if block, you need to call request.getSession(false) to get the session that was populated by the earlier POST. Think of the session as a global area that can be shared across requests. — jalynn2
Ahaaaa! I think must be the only combination of .getsession method I did not try! Cheers will try and post you as answer if works! — ChrisSherwood
@jalynn2 request.getSession(true) also uses existing session if that exists — Łukasz Rzeszotarski
@Lukasz - Agreed. The retrieval of the session could be moved prior to the if blocks. — jalynn2

Łukasz Rzeszotarski Łukasz Rzeszotarski · Accepted Answer · 2013-03-19T16:28:48

Do you really need separate ifs?

getSession(true) returns current session or create new if there is no current.

See at the documentation http://docs.oracle.com/javaee/6/api/javax/servlet/http/HttpServletRequest.html#getSession%28boolean%29

Getting a JSP servlet session, returns a null value

1 Answers