Comments on: Tutorial: HTTP Session handling using Servlet Filters

By: Chripin

Chripin — Mon, 19 Sep 2011 12:22:04 +0000

@Gisli I am getting the same problem. But when i use tomcat v6 i don’t get the problem.
My problem is that the values i place in the session are lost.
If you find the solution please update me.

By: Gisli

Gisli — Thu, 08 Sep 2011 17:46:30 +0000

I’m basically getting the same error as “learner”. I didn’t use this code but rather wrote my own. I have discovered that if I call getSession()/getSession(true), I always geta brand new session. If I call getSession(false) I always get null. I’ve been tearing my hair out over this the past few days. If I set session attributes in the filter and check them in the page where the filter redirects me to, I can read the values. But if I set attributes in the page, the filter never sees them because, as I said, getSession either returns null or a brand new session.

I’m using Tomcat 7.0.2. I’ve been using basic JSPs for years but this is the first time I create a servlet filter. I thought it was so brilliant until I hit this wall.

Hope you can help me. I would post the code but don’t have access to it right now.

By: Sandeep

Sandeep — Mon, 22 Aug 2011 14:13:50 +0000

Hi, I’m developing a web application using JSP. In my application, after user login, if he clicks back button of the browser, he should not go to the index page of my website. can u help me with this?

By: learner

learner — Wed, 23 Mar 2011 12:03:13 +0000

Hi I keep on getting The page isn’t redirecting properly error, any ideas?

thanks

By: Alex Vicente Chacón Jiménez

Alex Vicente Chacón Jiménez — Sun, 20 Feb 2011 16:32:38 +0000

Thank you very much for this article.
But I improved the example in the following way:

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException
	{

		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) res;
		String url = request.getServletPath();

		if (urlList.contains(url))
		{
			chain.doFilter(req, res);
		}
		else
		{
			HttpSession session = request.getSession(false);

			if (session == null )
			{
				response.sendRedirect(request.getContextPath());
			}
			else
			{
				chain.doFilter(req, res);
			}
		}
	}

This code prevent a java.lang.IllegalStateException: Cannot forward after response has been committed

By: raju

raju — Mon, 06 Dec 2010 18:23:57 +0000

wrt a prg html page(login.html) which accept username and password.Authenticaticate them using filters and then to helloworld servlet if the user is a valid .(if username is “genesis” print response as “hello” ,otherwise print response as “invaliduser” )……………

answer give me

By: sai

sai — Thu, 24 Jun 2010 04:09:30 +0000

Hi,

how can use this for ajax applications. per say, i have extjs spring applications. need to handle session time out or if session is not their, redirect to different page..

By: Nageswar

Nageswar — Thu, 10 Jun 2010 17:28:27 +0000

Hi I am getting StringTokenizer null pointer error, i Tried but same thing is comming.
if you have any solution plz send me

String urls = filterConfig.getInitParameter(“avoid-urls”);
StringTokenizer token = new StringTokenizer(urls, “,”);
urlList = new ArrayList();
while (token.hasMoreElements()) {
urlList.add(token.nextToken());
}
totalURLS = urlList.size();

By: Viral Patel

Viral Patel — Tue, 23 Feb 2010 18:41:35 +0000

@Chandra: The above example will work for you in any case. i.e. it will work for JSPs, Servlets or Struts2 as well. Filters are available for both servlets and JSPs because we have mapped /* url with filter SessionFilter.

By: Chandra

Chandra — Tue, 23 Feb 2010 17:53:16 +0000

Hi Viral,

Can we do the same thing..i.e when user copy paste the URL in new window, he must be redirected to Login page using JSPs. I am using Struts 2.0 framework. I am not using servlets. Filters are available for servlets only or for JSPs also?

TIA