java - JSP session is not null -


i'm newbie jsp , on particular page of webapp i'm trying determine whether user logged in. this, i'm checking session existance. if session not exist redirect user login page.

i'm confused fact following code 

<% if (null == session) out.println("session null"); else out.println("session not null"); if (null == request.getsession(false)) out.println("request.getsession() null"); else out.println("request.getsession() not null"); %>

under circumstances produces following output:

session not null request.getsession() not null

i don't understand why session exists when didn't create it. how check whether user logged in or not?

thanks in advance.

by default, session created container. jsp use 

<%@ page session="false" %>

to disable session creation on jsp.

in order check if user exists, need put token/key in session on server-side after user logged in. like

request.getsession().setattribute("usertoken","authenticated");

and on jsp check attribute exists , not null

if ("authenticated".equals(session.getattribute("usertoken")) { // }

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