Spring Boot REST Service Exception Handling

Handling exceptions in a REST service is crucial to ensure that the service returns meaningful error messages to the client in case of errors. Spring Boot provides several ways to handle exceptions in a REST service. In this blog post, we’ll be covering the steps to handle exceptions in a Spring Boot REST service using custom exceptions and @ControllerAdvice.



Exception Handling

  • Exception handling is an important aspect of any REST service.
  • Spring Boot provides several ways to handle exceptions in a REST service.
  • This article covers the steps to handle exceptions in a Spring Boot REST service using custom exceptions and @ControllerAdvice.


Define Custom Exceptions

  • A custom exception class is created to represent errors in the application.
  • The custom exception should extend RuntimeException.
  • Example:
class ResourceNotFoundException extends RuntimeException {
    public ResourceNotFoundException(String message) {
        super(message);
    }
}


Use @ControllerAdvice

  • @ControllerAdvice is used to handle exceptions globally across all controllers in the application.
  • The exception handler methods are annotated with @ExceptionHandler and specify the exception to be handled.
  • Example:
@ControllerAdvice
public class RestExceptionHandler {

    @ExceptionHandler(ResourceNotFoundException.class)
    public ResponseEntity<ErrorResponse> handleResourceNotFound(ResourceNotFoundException ex) {
        ErrorResponse error = new ErrorResponse("Resource not found", ex.getMessage());
        return new ResponseEntity<>(error, HttpStatus.NOT_FOUND);
    }

    @ExceptionHandler(Exception.class)
    public ResponseEntity<ErrorResponse> handleException(Exception ex) {
        ErrorResponse error = new ErrorResponse("Server error", ex.getMessage());
        return new ResponseEntity<>(error, HttpStatus.INTERNAL_SERVER_ERROR);
    }
}


Return Error Response

  • In the exception handler methods, return an error response with a meaningful error message and the appropriate HTTP status code.
  • Example error response:
class ErrorResponse {
    private String error;
    private String message;

    public ErrorResponse(String error, String message) {
        this.error = error;
        this.message = message;
    }
}


Raise Exceptions

  • In the REST controllers, raise custom exceptions when errors occur.
  • Example:
@GetMapping("/{id}")
public Resource getResourceById(@PathVariable("id") Long id) {
    Resource resource = resourceService.getResourceById(id);
    if (resource == null) {
        throw new ResourceNotFoundException("Resource with id " + id + " not found");
    }
    return resource;
}


Conclusion

  • Exception handling is an important aspect of any REST service.
  • Spring Boot provides several ways to handle exceptions in a REST service.
  • By using custom exceptions and @ControllerAdvice, you can handle exceptions globally and return meaningful error responses to the client.


Leave a Reply