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

Question

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

See also: