java - Is Spring HandlerInterceptorAdapter postHandle guaranteed?

Question

I currently have two interceptors that handle a similar function. I'd like to merge these.

One interceptor is an access request logger, that shows the logged in user, the session id, and the requested URL.

The other interceptor is a process time logger.

The access logger, in order to log all that must be logged, logs the request in the preHandle method. The idea is that regardless of what happens after (ie. exceptions), the exact access request will be there.

The process time logger however, due to its nature, must log in the postHandle method.

For merging this functionality, I'd have to move everything into a single postHandle method. However, it seems I may lose some logging if an exception occurs somewhere, especially one that is not (yet) handled properly in the application code.

Is there any guarantee or description as to these considerations?

Answer 1

You can consider merging the logic inside the afterCompletion which will be called even in the case when a handler method throws an exception. A good online example

public class RequestProcessingTimeInterceptor extends HandlerInterceptorAdapter {

    private static final Logger logger = LoggerFactory
            .getLogger(RequestProcessingTimeInterceptor.class);

    @Override
    public boolean preHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler) throws Exception {
        long startTime = System.currentTimeMillis();
        logger.info("Request URL::" + request.getRequestURL().toString()
                + ":: Start Time=" + System.currentTimeMillis());
        request.setAttribute("startTime", startTime);
        //if returned false, we need to make sure 'response' is sent
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        System.out.println("Request URL::" + request.getRequestURL().toString()
                + " Sent to Handler :: Current Time=" + System.currentTimeMillis());
        //we can add attributes in the modelAndView and use that in the view page
    }

    @Override
    public void afterCompletion(HttpServletRequest request,
            HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        long startTime = (Long) request.getAttribute("startTime");
        logger.info("Request URL::" + request.getRequestURL().toString()
                + ":: End Time=" + System.currentTimeMillis());
        logger.info("Request URL::" + request.getRequestURL().toString()
                + ":: Time Taken=" + (System.currentTimeMillis() - startTime));
    }
 }