Facelets custom error page - customize / wrap the exception message / stack trace

Question

I am using JBoss AS7. I already know how to use my own web.xml error pages for HTTP Errors (e.g. 404, 500, ...) - thats not a problem. But for debugging reasons I need to view the error StackTrace. How can I access the message that is shown by default and embed it in error page?

When you say "view the error stack trace" do you mean that you want to print it to the screen? — 8bitjunkie, Nov 22 '13 at 16:10
Thats exactly what i mean. But not on the console, but on the webpage (xhtml) for sure. — jp-jee, Nov 22 '13 at 16:12
Have you investigated the JSF ExceptionHandlerFactory mechanism? — 8bitjunkie, Nov 22 '13 at 16:16

score 2 · Accepted Answer · edited May 23 '17 at 12:07

The concrete exception instance is available as a request attribute with the name as keyed by RequestDispatcher#ERROR_EXCEPTION which has a value of javax.servlet.error.exception.

Thus, this will give you the exception:

#{requestScope['javax.servlet.error.exception']}

However, there's no standard facility to print its stack trace in the view. You'd need to homebrew an EL function, something like as JSF utility library OmniFaces already has in flavor of #{of:printStackTrace()}. You can see it in action in the OmniFaces FullAjaxExceptionHandler showcase page:

<ui:composition ... xmlns:of="http://omnifaces.org/functions">
...
<li>Stack trace: <pre><code>#{of:printStackTrace(requestScope['javax.servlet.error.exception'])}</code></pre></li>

whereby the function implementation look like this:

/**
 * Print the stack trace of the given exception.
 * @param exception The exception to print the stack trace for.
 * @return The printed stack trace.
 */
public static String printStackTrace(Throwable exception) {
    if (exception == null) {
        return null;
    }

    StringWriter stringWriter = new StringWriter();
    exception.printStackTrace(new PrintWriter(stringWriter, true));
    return stringWriter.toString();
}

Facelets custom error page - customize / wrap the exception message / stack trace

1 Answers1

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