Default Tomcat error pages look scary. In addition, they may expose valuable information including server version and exception stack trace. Servlet specification provides a way to configure an exceptional behavior through web.xml. One can configure either reaction on a specific Java exception or to a selected Http response code(s).

error-page element specifies a mapping between an error code or exception type to the path of a resource in the Web application:
 
 
 

<web-app>
 
 <!-- Prior to Servlet 3.0 define either an error-code or an exception-type but not both -->
 <error-page>
 <!-- Define error page to react on Java exception -->
 <exception-type>java.lang.Throwable</exception-type>
 <!-- The location of the resource to display in response to the error will point to the Spring MVC handler method -->
 <location>/error</location>
 </error-page>
 
 <error-page>
 <error-code>404</error-code>
 <location>/error</location>
 </error-page>
 
 <!-- With Servlet 3.0 and above general error page is possible -->
 <error-page>
 <location>/error</location>
 </error-page>
 
</web-app>

Having the custom error pages defined in our web.xml, we need to add the Spring MVC @Controller. The customError handler method wraps the information, that we retrieve from the request, and returns it to the view.

@Controller
class CustomErrorController {

 @RequestMapping("error") 
 public String customError(HttpServletRequest request, HttpServletResponse response, Model model) {
 // retrieve some useful information from the request
 Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
 Throwable throwable = (Throwable) request.getAttribute("javax.servlet.error.exception");
 // String servletName = (String) request.getAttribute("javax.servlet.error.servlet_name");
 String exceptionMessage = getExceptionMessage(throwable, statusCode);

 String requestUri = (String) request.getAttribute("javax.servlet.error.request_uri");
 if (requestUri == null) {
 requestUri = "Unknown";
 }

 String message = MessageFormat.format("{0} returned for {1} with message {3}", 
 statusCode, requestUri, exceptionMessage
 ); 

 model.addAttribute("errorMessage", message); 
 return "customError";
 }

 private String getExceptionMessage(Throwable throwable, Integer statusCode) {
 if (throwable != null) {
 return Throwables.getRootCause(throwable).getMessage();
 }
 HttpStatus httpStatus = HttpStatus.valueOf(statusCode);
 return httpStatus.getReasonPhrase();
 }
}

The produced message may look like following: 404 returned for /sandbox/bad with message Not Found.

To see the code in action, browse the source code of  Spring MVC Quickstart Archretype, or even better, generare a new project with it.