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jsfexceptionfaceletsstack-tracecustom-error-pages

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

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?

Solution

  • 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();
}

    See also: