Filter Problem

[shaf maff]

Hi Guys

I am playing around with a filter and am having problems getting it to work. Whenever I try to reload the app in tomcat manager, it stops running. As soon as I remove the filter stuff from the web.xml it starts to run again. See code below:


Servlet:

public final class AuthorisationFilter implements Filter 
{

    private FilterConfig filterConfig = null;
    private String attribute = null;

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

		
		User currentUser = (User)session.getAttribute("user");

		if (currentUser == null) {
			request.getRequestDispatcher("/test").forward(request, response);
		}

    }
	
	public void destroy() {
	
	}
	
    public void init(FilterConfig filterConfig) throws ServletException {

        this.filterConfig = filterConfig;
        this.attribute = filterConfig.getInitParameter("attribute");

    }
}

web.xml

<filter>
	<filter-name>SessionAuthorisation</filter-name>
	<filter-class>filter.AuthorisationFilter</filter-class>
	<description>
           Check for session. If none found, redirect to login.
	</description>
</filter>
		
<filter-mapping>
	<filter-name>SessionAuthorisation</filter-name>
	<url-pattern>/home/*</url-pattern>
</filter-mapping>

[Bear Bibeault]

Your filter is never allowing the chain to continue. See the Javadoc for the filter class.

[shaf maff]

Ok, I have updated the following:

if (currentUser == null) {  
     request.getRequestDispatcher("/test").forward(request, response);  
} else {
    chain.doFilter(request,response);
}

Not sure if thats what you meant but I compiled and tried to reload the project but it still doesn't run.

[Bear Bibeault]

Define "doesn't run".

[Paul Clapham]

You might find it useful to look at the examples here:

http://java.sun.com/products/servlet/Filters.html

[shaf maff]

Thanks for the link Paul, a good read.

I have another problem, I am trying to use response.setError() but compiler tells me 'symbol cannot be found'. It looks like its due to the fact that ServletResponse is being used and sendError works with HttpServletResponse. Is there anyway I can fix this ?

[Bear Bibeault]

Cast it.

[shaf maff]

Thanks bear. Is there anyway I can determine the source of the filter initialisation ? So if I refreshed index.jsp is there anyway the filter can tell me it was that file that triggered it ?

[Bear Bibeault]

The request is available to the filter from which it can gather any information it would like.

[shaf maff]

Do you have example code I could go through ?

[Bear Bibeault]

What info are you after? have you perused that JavaDoc for the request class?