Filter authentication won't display error page

[Dave Bosky]

I'm using a filter to verify a user exists in a list of groups before displaying the page.

If a user fails the verification filter they get sent to an error page.
The problem is the error page can't find my images, it will show the text on the page though. It seems the mappings get screwed up and being forwarded. How can I correct this?

Thanks.
Dave

[William Brogden]

The problem is the error page can't find my images

Suppose we restate the problem as "the browser can't find the images as my IMG tags are presently written."

Perhaps your error page needs to include a BASE tag to give a path to where the server has the images.
Bill

[David O'Meara]

You can change the error page so that it knows the absolute location of the images eg "/"+getContext()+"/images/error.jpg"

[Dave Bosky]

It seems like my filter-mapping is not allowing access to the images???
Is there a value to only check classes/jsp's and exclude everything else such as images?
Thanks Again,
Dave

<filter-mapping>
      <filter-name>AuthenticationFilter</filter-name>
      <url-pattern>/*</url-pattern>
</filter-mapping>    

[Ben Souther]

Originally posted by Dave Bosky:
It seems like my filter-mapping is not allowing access to the images???
Is there a value to only check classes/jsp's and exclude everything else such as images?
Thanks Again,
Dave

<filter-mapping>
      <filter-name>AuthenticationFilter</filter-name>
      <url-pattern>/*</url-pattern>
</filter-mapping>    

The problem is that your mapping is intercepting every call to the server, including requests for static files.
You should never use /*.

[Ben Souther]

Originally posted by Ben Souther:

<filter-mapping>
      <filter-name>AuthenticationFilter</filter-name>
      <url-pattern>/*</url-pattern>
</filter-mapping>    

<hr></blockquote>


The problem is that your mapping is intercepting every call to the server, including requests for static files.
You should never use /*.[/QB]

[almost never]

[Paul Clapham]

Okay, shouldn't use /*. So what's the url-pattern for "all servlets and JSPs"? Right now I'm using /* and my filter contains code to accept images and CSS files.

[Dave Bosky]

What code did you add to your filter to accept/ignore image/css files?

Thanks,
Dave

[Ben Souther]

Originally posted by Paul Clapham:
Okay, shouldn't use /*. So what's the url-pattern for "all servlets and JSPs"? Right now I'm using /* and my filter contains code to accept images and CSS files.

I did go back and add "almost never".


A better way to say it would have been:
Never use /* unless you really want to intercept EVERY request to the server.

[Dave Bosky]

I resolved the issue by adding an init-param to the filter config.

    
<filter>
    <init-param>
<param-name>ExcludedPages</param-name>
<param-value>gif,jpg,png,swf,js,html,css</param-value>
        <description>File extensions to exclude.</description>
    </init-param>
</filter>
 
// code in filter to check the page extension for excluded pages. 
        int pageMatch  = 0;
        currentPage = request.getServletPath().trim();
        Collection pages = new ArrayList();
        StringTokenizer st1 = new StringTokenizer(ExcludedPages, ",");
        while (st1.hasMoreTokens()) {
               pages.add(st1.nextToken().trim());
        }
        for (Iterator it = pages.iterator(); it.hasNext(); ) {
            String pg = (String) it.next();
            if (currentPage.endsWith(pg)) {
                pageMatch++;
            } //if
        } //for

Thanks,
Dave

[Bruno Boehr]

I have a suggestion regarding your code - just a minor change for greater efficiency. You are parsing the extensions string over and over againg for every request, although it could be done just once, at filter initialization. Besides, if you put all the extensions into a map, you would be able to find out if the requested resource is static simply by doing a lookup.

private Map excludedExtensionsMap = new HashMap();

public void init(FilterConfig cfg) throws ServletException {
String extensions = cfg.getInitParameter("ExcludedExtensions");
if (extensions != null) {
StringTokenizer st = new StringTokenizer(extensions, ",");
while (st.hasMoreTokens()) {
excludedExtensionsMap.put(st.nextToken().trim(), ""); // only the key matters here
}
}
}

// in doFilter()

boolean isStaticResource = false;

String path = request.getServletPath();
int pos = path.lastIndexOf(".");
if (pos >= 0) {
String ext = path.substring(pos + 1);
isStaticResource = excludedExceptionsMap.containsKey(ext);
}

// the rest of your filter logic

Don't get me wrong: this piece of code alone won't win you any noticeable gain in performance, but I am just making a point here: small code optimizations here and there can add up to substantial amounts of saved processor ticks.