How to grab uncaught exceptions in a Java servlet web application

Question

Is there a standard way to catch uncaught exceptions that happen inside of a java servlet container like tomcat or Jetty? We run a lot of servlets that come from libraries

Answer 1

I think a custom filter actually works best.

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    try {
        chain.doFilter(request, response);
    } catch (Throwable e) {
        doCustomErrorLogging(e);
        if (e instanceof IOException) {
            throw (IOException) e;
        } else if (e instanceof ServletException) {
            throw (ServletException) e;
        } else if (e instanceof RuntimeException) {
            throw (RuntimeException) e;
        } else {
            //This should never be hit
            throw new RuntimeException("Unexpected Exception", e);
        }
    }
}