HOW-TO: Custom error pages in Tomcat with Spring MVC

Rafal BorowiecNovember 26th, 2013Last Updated: November 25th, 2013

1 529 1 minute read

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.

Reference: HOW-TO: Custom error pages in Tomcat with Spring MVC from our JCG partner Rafal Borowiec at the Codeleak.pl blog.