How do I use JSP to track online user

Question

Hi,
I am using JPSs to build a website,and I want these JSPs to detect and display how many users are active browsing on my website and their usernames.I know I can use session to track cocurrent users online,but I had to use some external class to do that,so my Q is that is there pure JSP solution for this without use bean or call other class?
Thanks!
John

Answer 1

Okay,
I am fairly new to the whole JSP thing, but I
I understand what you are saying by putting the login
names into a vector. What I don't understand is how
you would set up the vector. I know this isnt going
to be syntactically correct but for example - :
In my file Logon.jsp lets say I have the following
code:
Vector v = new Vector();
String LoginName = session.getValue("login");
v.add(LoginName);
Now the problem I see with this code is that
t everytime someone logs in, Vector v is going to be
reset to a new empty vector and instead of adding to
an already existing vector, this code would just only
be able to hold at most, one login name. Where would
I declare my vector and how do I prevent it from being
wiped out? I am new to this, so please dont bash me
too hard.
EdThis is why you would want to use an external class.
Write a class which has the vector as an instance variable.
The class should have a method to add to the vector
when someone logs in and remove them when they log out.
Use the <jsp:useBean ... scope='application'> tag in your JSP.
This will make the class available to all JSPs in the application.
The first time your class is called it is instantiated.
After the first call it is read from the application object and
is not re-instantiated. You can call your add/remove methods from
a scriptlet in the JSP.