Using Forward and Include using RequestProcessor

[Sanjay Choudhary]

Hi All,

I have an application which contains 100+ jsp's.  Use case is to
inject the Javascript conditionally into the JSP's.  Condition is - If
a cookie is present in the request, inject the Javascript else leave
it alone.

I started with a simple struts example project for the proof of
concept.  I thought of a Servlet Filter and I created a filter as
below

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;

public class SecurePageFilter implements Filter {
    private static final String SECURITY_COOKIE = "ObSSOCookie";
    private static final String SECURITY_JS = "/check.js";

    public void init(FilterConfig filterConfig) throws ServletException {
    }

    public void destroy() {
    }

    public void doFilter(
        ServletRequest oRequest,
        ServletResponse oResponse,
        FilterChain oFilterChain)
        throws IOException, ServletException {

        oFilterChain.doFilter(oRequest, oResponse);

        HttpServletRequest woRequest = (HttpServletRequest) oRequest;
        Cookie[] aoCookies = woRequest.getCookies();
        String strUrl = woRequest.getRequestURI();

        if (strUrl != null
            && strUrl.endsWith("deleteCookie.jsp")
            || aoCookies == null)
            return;

        for (int i = 0; i < aoCookies.length; i++) {
            Cookie oCookie = aoCookies[i];

            if (oCookie.getName().equals(SECURITY_COOKIE)) {
                String strValue = oCookie.getValue();
                if (strValue != null && strValue.length() > 0) {
                    RequestDispatcher rd =
woRequest.getRequestDispatcher(SECURITY_JS);
                    rd.include(oRequest, oResponse);
                    oResponse.flushBuffer();
                    return;
                }
            }
        }
        return;
    } // doFilter

} // SecurePageFilter

My filter is mapped to (*.jsp and *.do) in the web.xml.

This works fine if I have a URI as
http://localhost:9080/struts-example/welcome.jsp

But this doesn't work if I use the URL
http://localhost:9080/struts-example/welcome.do


To explore more I downloaded Struts 1.2 source and took a look in
RequestDispatcher class --> processForward(..) , processInclude(..),
doForward(..) and doInclude(..) methods.  And off course, process(..)
method. In the process method , if request is forwarded using the
RequestDispatcher, which is normally the case in *.do types URI's,
control is returned back to the servlet without processing the
'processInclude'.  I further extended the RequestDispatcher class and
implemented my own doForward method. This is more or less same as
Struts implementation but also calls includes. Code is as below :-
    protected void doForward(
        String uri,
        HttpServletRequest request,
        HttpServletResponse response)
        throws IOException, ServletException {

        // Unwrap the multipart request, if there is one.
        if (request instanceof MultipartRequestWrapper) {
            request = ((MultipartRequestWrapper) request).getRequest();
        }

        RequestDispatcher rd = getServletContext().getRequestDispatcher(uri);
        if (rd == null) {
            response.sendError(
                HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
                getInternal().getMessage("requestDispatcher", uri));
            return;
        }
        rd.forward(request, response);
       doIncludeJS(request,response);        
    }

    protected void doIncludeJS(
        HttpServletRequest request,
        HttpServletResponse response)
        throws IOException, ServletException {
        Cookie[] aoCookies = request.getCookies();
        String strUrl = request.getRequestURI();

        if (strUrl != null
            && strUrl.endsWith("deleteCookie.jsp")
            || aoCookies == null)
            return;


        for (int i = 0; i < aoCookies.length; i++) {
            Cookie oCookie = aoCookies[i];

            if (oCookie.getName().equals(SECURITY_COOKIE)) {
                String strValue = oCookie.getValue();
                if (strValue != null && strValue.length() > 0) {
                                        doInclude(SECURITY_JS,request, response);
                    break;
                }
            }
        }
        return;
    }

Still to my surprise, JS file did not get injected in the response.( I
debugged the application do ensure that doInclude(..) method is
called)

[Q1] - Can we use RequestDispatcher to Forward and Include for the
same request/response?  (I know we can't do Include and Forward, it
throws an error. But in case of Forward and Include no error is thrown
but nothing gets included).

[Q2] - Is there anyother way of including into request with URI like *.do?


Any help is highly appreciated.

Thanks,

Sanjay

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