Display popup message when user login to site in J2EE(Filters)

I would like to show a popup message to the users on login to my site, only when login (later on it is not required).

We are using java/j2ee fo开发者_StackOverflow社区r my application, and authentication provided using the Filters, once login success we are redirecting the request to the requested page (it is not the same always it depends on user access but any access to our application there authentication will be performed). Here I want to display a popup message to the user on login.

Where can I use the popup message to display to the user?

You could use a session variable for this. In every page check if the session variable is null and if it isn't show the pop-up and initialize it.