인프런 커뮤니티 질문&답변

package hello.exception.servlet;

import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Slf4j
@Controller
public class ErrorPageController {
    //RequestDispatcher 상수로 정의되어 있음
    public static final String ERROR_EXCEPTION = "jakarta.servlet.error.exception";
    public static final String ERROR_EXCEPTION_TYPE = "jakarta.servlet.error.exception_type";
    public static final String ERROR_MESSAGE = "jakarta.servlet.error.message";
    public static final String ERROR_REQUEST_URI = "jakarta.servlet.error.request_uri";
    public static final String ERROR_SERVLET_NAME = "jakarta.servlet.error.servlet_name";
    public static final String ERROR_STATUS_CODE = "jakarta.servlet.error.status_code";
    
    @RequestMapping("/error-page/404")
    public String errorPage404(HttpServletRequest request, HttpServletResponse
            response) {
        log.info("errorPage 404");
        printErrorInfo(request);
        return "error-page/404";
    }
    @RequestMapping("/error-page/500")
    public String errorPage500(HttpServletRequest request, HttpServletResponse response) {
        log.info("errorPage 500");
        printErrorInfo(request);
        return "error-page/500";
    }
    private void printErrorInfo(HttpServletRequest request) {
        log.info("ERROR_EXCEPTION: ex=", request.getAttribute(ERROR_EXCEPTION));
        log.info("ERROR_EXCEPTION_TYPE: {}", request.getAttribute(ERROR_EXCEPTION_TYPE));
        log.info("ERROR_MESSAGE: {}", request.getAttribute(ERROR_MESSAGE)); 
        // ex의 경우 NestedServletException 스프링이 한번 감싸서 반환
        log.info("ERROR_REQUEST_URI: {}", request.getAttribute(ERROR_REQUEST_URI));
        log.info("ERROR_SERVLET_NAME: {}", request.getAttribute(ERROR_SERVLET_NAME));
        log.info("ERROR_STATUS_CODE: {}", request.getAttribute(ERROR_STATUS_CODE));
        log.info("dispatchType={}", request.getDispatcherType());
    }
}

2023-08-13T23:49:48.327+09:00  INFO 11300 --- [nio-8080-exec-6] h.exception.servlet.ErrorPageController  : errorPage 500
2023-08-13T23:49:48.327+09:00  INFO 11300 --- [nio-8080-exec-6] h.exception.servlet.ErrorPageController  : ERROR_EXCEPTION: ex=
2023-08-13T23:49:48.327+09:00  INFO 11300 --- [nio-8080-exec-6] h.exception.servlet.ErrorPageController  : ERROR_EXCEPTION_TYPE: null
2023-08-13T23:49:48.328+09:00  INFO 11300 --- [nio-8080-exec-6] h.exception.servlet.ErrorPageController  : ERROR_MESSAGE: null
2023-08-13T23:49:48.328+09:00  INFO 11300 --- [nio-8080-exec-6] h.exception.servlet.ErrorPageController  : ERROR_REQUEST_URI: null
2023-08-13T23:49:48.328+09:00  INFO 11300 --- [nio-8080-exec-6] h.exception.servlet.ErrorPageController  : ERROR_SERVLET_NAME: null
2023-08-13T23:49:48.328+09:00  INFO 11300 --- [nio-8080-exec-6] h.exception.servlet.ErrorPageController  : ERROR_STATUS_CODE: null
2023-08-13T23:49:48.328+09:00  INFO 11300 --- [nio-8080-exec-6] h.exception.servlet.ErrorPageController  : dispatchType=REQUEST

// WebServerCustomizer

package hello.exception;

import org.springframework.boot.web.server.ConfigurableWebServerFactory;
import org.springframework.boot.web.server.ErrorPage;
import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;

@Component
public class WebServerCustomizer implements WebServerFactoryCustomizer<ConfigurableWebServerFactory> {

    @Override
    public void customize(ConfigurableWebServerFactory factory) {

        ErrorPage errorPage404 = new ErrorPage(HttpStatus.NOT_FOUND, "/error-page/404");
        ErrorPage errorPage500 = new ErrorPage(HttpStatus.INTERNAL_SERVER_ERROR, "/error-page/500");
        ErrorPage errorPageEx = new ErrorPage(RuntimeException.class, "/error-page/500");

        factory.addErrorPages(errorPage404, errorPage500, errorPageEx);
    }
}

// ServerExController

package hello.exception.servlet;

import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

import java.io.IOException;

@Slf4j
@Controller
public class ServletExContoller {

    // Exception (예외)
    @GetMapping("/error-ex")
    public void errorEx() {
        throw new RuntimeException("예외 발생!");
        // HTTP Status 500 – Internal Server Error 발생
    }

    // response.sendError(HTTP 상태 코드, 오류 메시지)
    @GetMapping("/error-404")
    public void error404(HttpServletResponse response) throws IOException {
        response.sendError(404, "404 오류!");
    }

    @GetMapping("/error-500")
    public void error500(HttpServletResponse response) throws IOException {
        response.sendError(500);
    }
}

스프링부트 3.1.2 버젼으로 생성해서 String 상수의 "javax"를 "jakarta"로 변경한 것 외엔 강의에서 사용된 코드와 동일하게 작성하였습니다.

그런데 /error-ex 로 접속할땐 상수값에 담긴 정보가 정상적으로 나오지만 /error-page/500, /error-page/404 로 접속하면 상수에 담긴 정보가 모두 null 로 나옵니다.

/error-page/500, /error-page/404 로 접속할땐 request.getAttribute() 에 아예 값이 안들어가는 것 같은데 무엇이 문제일까요?