spring-exception-handler

Project shows how to provide implemenation of error-handling in spring boot application

preface

Spring MVC

After Spring 3.2 Spring MVC provides new features to handling with exception: @ControllerAdviceand
@Rest@ControllerAdvice, and upgrades it in Spring 4

Classes annotated with @ControllerAdvice can contain @ExceptionHandler, @InitBinder, and @ModelAttribute annotated methods, and these methods will apply to @RequestMapping methods across all controller hierarchies as opposed to the controller hierarchy within which they are declared.

@RestControllerAdvice is an alternative where @ExceptionHandler methods assume @ResponseBody semantics by default.

Spring WS

To Handling Exceptions we have to :

• annotate exception classes with the @SoapFault annotation, to indicate the SOAP Fault that should be returned whenever that exception is thrown
• using SoapFaultMappingExceptionResolver, which enables you to customize SOAP Fault of any exception thath might be thrown

project description

Project is build in hexagonal architectural style :

• app: contains rest controller and soap endpoint

• domain : contains model, bussines logic and port to infrastructure

  port :

  public interface OrderRepository {
   Optional<Order> findById(Integer orderId);
  }
  

  bussiness logic :

  public class OrderService {
  
  private final OrderRepository repository;
  
  public Order findById(@NonNull Integer orderId) {
    return repository
          .findById(orderId)
          .orElseThrow(() -> new NoResultException("No result for order id = " + orderId));
  }
  }
  

• infrastructure : contains configuration of rest, soap and adapter to repository

  adapter simualates repository :

  ...
  class OrderRepositoryAdapter implements OrderRepository {
  
  @Override
  public Optional<Order> findById(@NotNull Integer orderId) {
     switch (orderId) {
        case 0 : throw new IllegalArgumentException("orderId cannot be 0");
        case 1 : return Optional.empty();
        case 2 : return buildOrder(orderId);
        default: throw new IllegalStateException("Illegal state");
    }
  }
  ...
  

assumptions and implemenation

Project focuces on handling error using RestControllerAdvice and SoapFaultMappingExceptionResolver.

error handling assumptions:

• when IllegalArgumentException is thorwn out then response shoudl have BAD_REQUEST status and erorr massage
• when bussines exception (NoResultException) is throwm out then reponse should have NOT_FOUND status and erorr massage
• when other exception is thrown out then reponse should have INTERNAL_SERVER_ERROR status

Rest

Reference: https://spring.io/blog/2013/11/01/exception-handling-in-spring-mvc

In Spring 4.0 handling exception is enabled by @RestControllerAdvice mixing with @ExceptionHandler and customize error json :

Error Json :

...
class MessageExceptionJson {
  String url;
  String message;
}

Interception with @RestControllerAdvice

@RestControllerAdvice
class RestExceptionInterceptor {
...
}

and configuration using @ExceptionHandler :

handling IllegalArgumentException

@ResponseStatus(code = HttpStatus.BAD_REQUEST)
@ExceptionHandler(IllegalArgumentException.class) MessageExceptionJson
handleException(HttpServletRequest request, IllegalArgumentException exception) {
   return MessageExceptionJson.builder()
             .url(request.getRequestURI())
             .message(exception.getLocalizedMessage())
             .build();
 }

handling NoResultException

 @ResponseStatus(code = HttpStatus.NOT_FOUND)
 @ExceptionHandler(NoResultException.class) MessageExceptionJson
 handleException(HttpServletRequest request, NoResultException exception) {
      return MessageExceptionJson.builder()
              .url(request.getRequestURI())
              .message(exception.getLocalizedMessage())
              .build();
  }

handling Excpetion

@ResponseStatus(code = HttpStatus.INTERNAL_SERVER_ERROR)
@ExceptionHandler MessageExceptionJson
 handleException(HttpServletRequest request, Exception exception) {
      return MessageExceptionJson.builder()
              .url(request.getRequestURI())
              .message("Something go wrong !")
              .build();
  }

notes

When ControllerAdive or RestControllerAdive is used more than once , then spring registeres all of them.
If @ControllerAdvice with an @ExceptionHandler for Exception gets registered before another @ControllerAdvice class with an @ExceptionHandler for a more specific exception, then first one will get called. To avoid this problem , use '@Order' to control order of registering ControllerAdiveBean in Spring.

Reference: https://stackoverflow.com/questions/19498378/setting-precedence-of-multiple-controlleradvice-exceptionhandlers

SOAP

In the SOAP error handling is enabled by SoapFaultMappingExceptionResolver and override customizeFault method

public class SoapExceptionInterceptor extends SoapFaultMappingExceptionResolver {

  @Override
  protected void customizeFault(Object endpoint, Exception ex, SoapFault fault) {
  ...
  }

and registered bean SoapFaultMappingExceptionResolver

@Bean SoapFaultMappingExceptionResolver
  exceptionResolver() {
      SoapFaultMappingExceptionResolver exceptionResolver = new SoapExceptionInterceptor();

      SoapFaultDefinition faultDefinition = new SoapFaultDefinition();
      faultDefinition.setFaultCode(SoapFaultDefinition.SERVER);
      exceptionResolver.setDefaultFault(faultDefinition);

      Properties errorMappings = new Properties();
      errorMappings.setProperty(SoapFaultHandler.class.getName(), SoapFaultDefinition.SERVER.toString());
      exceptionResolver.setExceptionMappings(errorMappings);
      exceptionResolver.setOrder(1);
      return exceptionResolver;
  }