This issue get Resolved using beans & scriptlet. in the Jsp page i have import my java class(StoreUsrDetails) and declare a jsp use bean (storeusr).
In jsp page
<%@page import="com.thomsonreuters.alpaca.StoreUsrDetails" %>
<jsp:useBean id="storeusr" class="com.thomsonreuters.alpaca.StoreUsrDetails" scope="request" />
using the bean i call a method inside my java method (validateUser) which returns wheather the user details is present in the database or not. after that i have written a scriplet code at the start of my jsp body. And based on the retun value of validateUser method i redirect them to another page.
Jsp Body
<body>
<%
if(storeusr.validateUser(request.getRemoteUser()))
response.sendRedirect("ListProjects.jsp");
%>