How do you store Java objects in HttpSession

Question

So I am trying to get a servlet to add a Java object to the session of the user  when this servlet is requested  But after the servlet redirects to the next page and I try to retrieve the object  I get a null object instead   Here is what I do to add the object to the HttpSession  in the servlet    request setAttribute  object   obj     Then I try to retrieve it by  in the JSP     Object obj   request getAttribute  object      So how would I get obj to not be null   Update  I have also tried this with nothing   HttpSession session   request getSession    session setAttribute  object   obj     with the following in the JSP    Object obj   request getSession   getAttribute  object      Both ways still return null

User · Answer

You are not adding the object to the session, instead you are adding it to the request.
What you need is:

HttpSession session = request.getSession();
session.setAttribute("MySessionVariable", param);

In Servlets you have 4 scopes where you can store data.

Application
Session
Request
Page

Make sure you understand these. For more look here

User · Answer

The request object is not the session   You want to use the session object to store   The session is added to the request and is were you want to persist data across requests   The session can be obtained from   HttpSession session   request getSession true     Then you can use setAttribute or getAttribute on the session   A more up to date tutorial on jsp sessions is  http   courses coreservlets com Course-Materials pdf csajsp2 08-Session-Tracking pdf

User · Answer

Add it to the session  not to the request   HttpSession session   request getSession    session setAttribute  object   object     Also  don t use scriptlets in the JSP  Use EL instead  to access object all you need is   object       A primary feature of JSP technology version 2 0 is its support for an expression language  EL   An expression language makes it possible to easily access application data stored in JavaBeans components  For example  the JSP expression language allows a page author to access a bean using simple syntax such as   name  for a simple variable or   name foo bar  for a nested property

User · Answer

Here you can do it by using HttpRequest or HttpSession  And think your problem is within the JSP   If you are going to use the inside servlet do following   Object obj   new Object    session setAttribute  object   obj     or  HttpSession session   request getSession    Object obj   new Object    session setAttribute  object   obj     and after setting your attribute by using request or session  use following to access it in the JSP    lt    request getAttribute  object    gt    or   lt    session getAttribute  object    gt    So seems your problem is in the JSP   If you want use scriptlets it should be as follows    lt   Object obj   request getSession   getAttribute  object    out print obj     gt    Or can use expressions as follows    lt    session getAttribute  object    gt    or can use EL as follows    object  or   sessionScope object

[java] How do you store Java objects in HttpSession?

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