redirecting from a servlet filter to jsf returns the actual jsf code not rendered to html

Question

below is my code;

    /*
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package racms;

import java.io.IOException;
import javax.faces.application.NavigationHandler;
import javax.faces.context.FacesContext;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


@WebFilter("/faces/*")
public class AuthenticationFilter implements Filter {

    @Override
    public void init(FilterConfig config) throws ServletException {
        // If you have any <init-param> in web.xml, then you could get them
        // here by config.getInitParameter("name") and assign it as field.
    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;
        HttpSession session = request.getSession(false);

        String pageRequested = request.getRequestURI().toString(); 
        //try{
        //FacesContext fctx = FacesContext.getCurrentInstance();
        //NavigationHandler myNav = fctx.getApplication().getNavigationHandler();



         if(session==null){       
               session = request.getSession(true); // will create a new session     
               response.sendRedirect("Login.xhtml");       
               //myNav.handleNavigation(fctx, null, "Login");
         }else if(session==null && pageRequested.contains("Login.xhtml")){       
                //  session.getAttribute("user");     
                chain.doFilter(request, response); // continue filtering       
         }else if((session.getAttribute("user")== null) && (!pageRequested.contains("Login.xhtml"))){          
             response.sendRedirect("Login.xhtml");
             //myNav.handleNavigation(fctx, null, "Login");
         }else {
             chain.doFilter(request, response);
         }
        //}catch(Exception e){
        //    System.out.println("Error :"+ e);
        //}
        /*if ((((HttpServletRequest) req).getSession().getAttribute("user") == null)) {
            FacesContext fctx = FacesContext.getCurrentInstance();
            NavigationHandler myNav = fctx.getApplication().getNavigationHandler();
            myNav.handleNavigation(fctx, null, "Login");
            //response.sendRedirect(request.getContextPath() + "/Login.xhtml"); // No logged-in user found, so redirect to login page.
        } else {
            chain.doFilter(req, res); // Logged-in user found, so just continue request.
        }*/
    }

    @Override
    public void destroy() {
        // If you have assigned any expensive resources as field of
        // this Filter class, then you could clean/close them here.
    }

}

If i use FacesContext.getCurrentInstance(), java.lang.Nullpointer Exception occurs; If i use response.sendRedirect("Login.xhtml"); it shows a blank page, if i do view source, i can see the source of Login.xhtml in jsf. it is not rendered to html..

what i want to do is: if the user is not logged in and accessing any page then send him to Login.xhtml, if the user is on Login.xhtml then show him the page to login.

please help..

Answer 1

Redirect to an URL that matches the FacesServlet mapping. Apparently it is mapped on /faces/* instead of *.xhtml. Then redirect to faces/Login.xhtml.

Here's a rewrite, which simplifies the logic:

@Override
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
    HttpServletRequest request = (HttpServletRequest) req;
    HttpServletResponse response = (HttpServletResponse) res;
    HttpSession session = request.getSession(false);
    User user = (session != null) ? (User) session.getAttribute("user") : null;
    String loginURL = request.getContextPath() + "/faces/Login.xhtml"; 

    if (user == null && !request.getRequestURI().equals(loginURL)) {       
        response.sendRedirect(loginURL);
    } else {
        chain.doFilter(request, response);
    }
}