Very Simple Example。Http Session is stateless, keep track what user is doing.
SessionServlet
public class SersionServlet extends HttpServlet implements Servlet {
HttpSerssions session = request.getSession(false); //takes any two params, false, if user has session, give it to me; true, if user has no session, create one
if(session == null) {
session = reuqest.getSession(true);
session.setAttribute(“count”, hitCount);
}
Integer hitCount = (Integer)session.getAttribte(“count”);
hitCount = new Integer(hitCount.intValue()) + 1;
response.getWriter().print(“Number of times at this page ” + hitCount.intValue() );
}
So, when user hit this servlet, it will be increased by 1 everytime user refreshes the page.