Spring MVC Error Handling Example

This post describes the different techniques to perform error handling in Spring MVC 3. The code is available on GitHub in the Spring-MVC-Error-Handling directory. It is based on the Spring MVC With Annotations examples.

Handling Exceptions Before Spring 3

Before Spring 3, exceptions were handled with HandlerExceptionResolvers. This interface defines a single method:
 
 
 

ModelAndView resolveException(
  HttpServletRequest request,
  HttpServletResponse response,
  Object handler,
  Exception ex)

Notice it returns a ModelAndView object. Therefore, encountering an error meant being forwarded to a special page. However, this method is not suited for REST Ajax calls to JSONs (for example). In this case, we do not want to return a page, and we may want to return a specific HTTP status code. A solution, described further, is available.

For the sake of this example, two fake CustomizedException1 and CustomizedException2 exceptions have been created. To map customized exceptions to views, one could (and can still) use a impleMappingExceptionResolver:

SimpleMappingExceptionResolver getSimpleMappingExceptionResolver() {

    SimpleMappingExceptionResolver result
        = new SimpleMappingExceptionResolver();

    // Setting customized exception mappings
    Properties p = new Properties();
    p.put(CustomizedException1.class.getName(), 'Errors/Exception1');
    result.setExceptionMappings(p);

    // Unmapped exceptions will be directed there
    result.setDefaultErrorView('Errors/Default');

    // Setting a default HTTP status code
    result.setDefaultStatusCode(HttpStatus.BAD_REQUEST.value());

    return result;

}

We map CustomizedException1 to the Errors/Exception1 JSP page (view). We also set a default error view for unmapped exception, namely CustomizedException2 in this example. We also set a default HTTP status code.

Here is the Exception1 JSP page, the default page is similar:

<%@page contentType='text/html' pageEncoding='UTF-8'%>
<%@ taglib prefix='c' uri='http://java.sun.com/jsp/jstl/core' %>
<!doctype html>
<html lang='en'>
<head>
  <meta http-equiv='Content-Type' content='text/html;' charset=UTF-8'>
  <title>Welcome To Exception I !!!</title>
</head>
<body>
    <h1>Welcome To Exception I !!!</h1>
    Exception special message:<
    ${exception.specialMsg}
    <a href='<c:url value='/'/>'>Home</a>
</body>
</html>

We also create a dummy error controller to help triggering these exceptions:

@Controller
public class TriggeringErrorsController {

    @RequestMapping(value = '/throwCustomizedException1')
    public ModelAndView throwCustomizedException1(
        HttpServletRequest request,HttpServletResponse response)
            throws CustomizedException1 {

        throw new CustomizedException1(
            'Houston, we have a problem!');
    }

    @RequestMapping(value = '/throwCustomizedException2')
    public ModelAndView throwCustomizedException2(
        HttpServletRequest request,HttpServletResponse response)
            throws CustomizedException2 {

        throw new CustomizedException2(
            'Something happened on the way to heaven!');
    }

    ...

}

Before Spring 3, one would declare a SimpleMappingExceptionResolver as a @Bean in web.xml. However, we will use a HandlerExceptionResolverComposite which we will describe later.

We also configure a target page for HTTP status codes in web.xml, which is an other way to deal with issues:

<error-page>
    <error-code>404</error-code>
    <location>/WEB-INF/pages/Errors/My404.jsp</location>
</error-page>

 
What Is New Since Spring 3.X?

The @ResponseStatus annotation is a new mean to set a Http status code when a method is invoked. These are handled by the ResponseStatusExceptionResolver. The @ExceptionHandler annotation facilitates the handling of exceptions in Spring. Such annotations are processed by the AnnotationMethodHandlerExceptionResolver.

The following illustrates how these annotations can be used to set an HTTP status code to the response when our customized exception is triggered. The message is returned in the response’s body:

@Controller
public class TriggeringErrorsController {

    ...

    @ExceptionHandler(Customized4ExceptionHandler.class)
    @ResponseStatus(value=HttpStatus.BAD_REQUEST)
    @ResponseBody
    public String handleCustomized4Exception(
        Customized4ExceptionHandler ex) {

        return ex.getSpecialMsg();

    }

    @RequestMapping(value = '/throwCustomized4ExceptionHandler')
    public ModelAndView throwCustomized4ExceptionHandler(

        HttpServletRequest request,HttpServletResponse response)
            throws Customized4ExceptionHandler {

        throw new Customized4ExceptionHandler('S.O.S !!!!');

    }

}

On the user side, if one uses an Ajax call, the error can be retrieved with the following (we are using JQuery):

$.ajax({
    type: 'GET',
    url:  prefix + '/throwCustomized4ExceptionHandler',
    async: true,
    success: function(result) {
        alert('Unexpected success !!!');
    },
    error: function(jqXHR, textStatus, errorThrown) {
        alert(jqXHR.status + ' ' + jqXHR.responseText);
    }
});

Some people using Ajax like to return a JSON with the error code and some message to handle exceptions. I find it overkill. A simple error number with a message keeps it simple.

Since we are using several resolvers, we need a composite resolver (as mentioned earlier):

@Configuration
public class ErrorHandling {

    ...

    @Bean
    HandlerExceptionResolverComposite getHandlerExceptionResolverComposite() {

        HandlerExceptionResolverComposite result
            = new HandlerExceptionResolverComposite();

        List<HandlerExceptionResolver> l
            = new ArrayList<HandlerExceptionResolver>();

        l.add(new AnnotationMethodHandlerExceptionResolver());
        l.add(new ResponseStatusExceptionResolver());
        l.add(getSimpleMappingExceptionResolver());
        l.add(new DefaultHandlerExceptionResolver());

        result.setExceptionResolvers(l);

        return result;

}

The DefaultHandlerExceptionResolver resolves standard Spring exceptions and translates them to corresponding HTTP status codes.

Running The Example

Once compiled, the example can be run with mvn tomcat:run. Then, browse:

http://localhost:8585/spring-mvc-error-handling/

The main page will look like this:

If you click on the Exception 1 link, the following page will display:

If you click on the Exception 2 link, the following page will display:

If you click on the Exception Handler button, a pop-up will be displayed:

These techniques are enough to cover error handling in Spring.

More Spring related posts here.
 

Reference: Spring MVC Error Handling from our JCG partner Jerome Versrynge at the Technical Notes blog.

Related Whitepaper:

Introduction to Web Applications Development

Kick start your web apps development with this introductory ebook!

This 376 page eBook 'Introduction to Web Applications Development', starts with an introduction to the internet, including a brief history of the TCT/IP protocol and World Wide Web. It defines the basic concepts for web servers and studies the case of Apache, the most used webserver, while other free software webservers are not forgotten. It continues with webpage design focusing on HTML and JavaScript. XML Schemas, their validation and transformation are covered as well as dynamic webpages built with CGI, PHP or JSP and database access.

Get it Now!  

One Response to "Spring MVC Error Handling Example"

  1. DSR says:

    Nice tutorial…
    I’ve a doubt in throwing exception from DAO layer. If I throw an exception like “throw MyException(“Duplicate entry”)”, I need to show this message in the same screen where user performs submission. Means I do not need to show error message in new screen, but in the same screen at the top. How can achieve this…Pls give some idea to accomplish this…

Leave a Reply


6 − five =



Java Code Geeks and all content copyright © 2010-2014, Exelixis Media Ltd | Terms of Use
All trademarks and registered trademarks appearing on Java Code Geeks are the property of their respective owners.
Java is a trademark or registered trademark of Oracle Corporation in the United States and other countries.
Java Code Geeks is not connected to Oracle Corporation and is not sponsored by Oracle Corporation.

Sign up for our Newsletter

15,153 insiders are already enjoying weekly updates and complimentary whitepapers! Join them now to gain exclusive access to the latest news in the Java world, as well as insights about Android, Scala, Groovy and other related technologies.

As an extra bonus, by joining you will get our brand new e-books, published by Java Code Geeks and their JCG partners for your reading pleasure! Enter your info and stay on top of things,

  • Fresh trends
  • Cases and examples
  • Research and insights
  • Two complimentary e-books
Get tutored by the Geeks! JCG Academy is a fact... Join Now
Hello. Add your message here.