Handling controller exceptions on Spring Boot

ErrorHandlerControllerAdvice.kt

/*
 * Based on: https://docs.spring.io/spring-boot/docs/2.1.3.RELEASE/reference/htmlsingle/#boot-features-error-handling
 */

package com.myorg.myproject.controller.advice

import org.springframework.http.HttpStatus
import org.springframework.web.bind.annotation.ExceptionHandler
import org.springframework.web.bind.annotation.RestControllerAdvice
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler
import java.time.OffsetDateTime
import javax.servlet.http.HttpServletRequest

abstract class HttpException(val status: HttpStatus, message: String? = null) : Exception(message)
class BadRequestException(message: String? = null) : HttpException(HttpStatus.BAD_REQUEST, message)
class NotFoundException(message: String? = null) : HttpException(HttpStatus.NOT_FOUND, message)

class ErrorResponse(
        val status: Int,
        val message: String
) {
    val timestamp: OffsetDateTime = OffsetDateTime.now()
}

@RestControllerAdvice(basePackages = ["com.myorg.myproject.controller"])
class ErrorHandlerControllerAdvice : ResponseEntityExceptionHandler() {

    @ExceptionHandler(HttpException::class)
    fun handleNotFoundException(request: HttpServletRequest, ex: HttpException): ErrorResponse {
        val status = ex.status
        return ErrorResponse(status.value(), ex.message ?: status.reasonPhrase)
    }

    @ExceptionHandler(Exception::class)
    fun handleException(request: HttpServletRequest, ex: Exception): ErrorResponse {
        val status = getStatus(request)
        return ErrorResponse(status.value(), ex.message ?: status.reasonPhrase)
    }

    private fun getStatus(request: HttpServletRequest): HttpStatus {
        val statusCode = request.getAttribute("javax.servlet.error.status_code") as Int?
                ?: return HttpStatus.INTERNAL_SERVER_ERROR
        return HttpStatus.valueOf(statusCode)
    }

}