Jetty http session is always null (Embedded Contai

问题:

I am trying to implement a simple servlet which uses a HTTP session in an embedded jetty (7.3.0 v20110203) container. To start jetty I use the following code:

Server server = new Server(12043);
ServletContextHandler handler = new
            ServletContextHandler(ServletContextHandler.SESSIONS);
handler.setContextPath("/");
server.setHandler(handler);
ServletHolder holder = new ServletHolder(new BaseServlet());
handler.addServlet(holder, "/*");
server.start();
server.join();

The servlet acquires a session with

HttpSession session = request.getSession(true);

and stores some data in it. Upon the next request it gets the session with the following code:

HttpSession session = request.getSession(false);

and there the session is always null.

I did not find any information on the internet about this particular problem. I have also experimented with setting a SessionManager or SessionIdManager, but that did not seem to change anything. I suspect I am missing something about SessionManager or SessionIdManager or SessionHandler here, but this is just a wild guess.

回答1:

Your code works fine with this skeletal implementation of BaseServlet:

public class BaseServlet extends HttpServlet {
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) {
        boolean create = "true".equals(req.getParameter("create"));

        HttpSession session = req.getSession(create);
        if (create) {
            session.setAttribute("created", new Date());
        }

        PrintWriter pw = new PrintWriter(resp.getOutputStream());
        pw.println("Create = " + create);
        if (session == null) {
            pw.println("no session");
        } else {
            pw.println("Session = " + session.getId());
            pw.println("Created = " + session.getAttribute("created"));
        }

        pw.flush();
    }

so the session is probably being invalidated somewhere else in your code.

The SessionHandler can also be explicity set using the setSessionHandler() method of ServletContextHandler.

回答2:

//You need to setup SessionManager first. This worked for me.
Server server = new Server(8031);
ServletHandler handler = new ServletHandler();
server.setHandler(handler);

HashSessionIdManager hashSessionIdManager = new 
HashSessionIdManager();
SessionHandler sessionHandler = new SessionHandler();
SessionManager sessionManager = new HashSessionManager();
sessionManager.setSessionIdManager(hashSessionIdManager);
sessionHandler.setSessionManager(sessionManager);
sessionHandler.setHandler(handler);
sessionHandler.setServer(server);
server.setSessionIdManager(hashSessionIdManager);
ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
context.setContextPath("/");
context.addServlet("webservlet.IndexServlet", "/index");
context.addServlet("webservlet.HomeServlet", "/home");
context.addServlet("webservlet.CategoryServlet", "/category");
context.addServlet("webservlet.ProductServlet", "/product");
...

回答3:

The method HttpServletResponse#reset() destroys a newly created session, so a new one is created the next time and so on.