Inflearn Community Q&A

강의를 따라가다 문득 preHandle, postHandle, afterCompletion 의 순서를 알고 싶어서 LoginCheckInterceptor 에 해당 메서드를 추가하여 로그를 찍어보았습니다.

질문은 맨 밑에 있으며, 코드는 이해를 돕기 위해 첨부했습니다.

LogInterceptor

@Slf4j
public class LogInterceptor implements HandlerInterceptor {
    public static final String LOG_ID = "logId";

    @Override
    public boolean preHandle(
            HttpServletRequest request,
            HttpServletResponse response,
            Object handler
    ) throws Exception {
        String requestURI = request.getRequestURI();
        String uuid = UUID.randomUUID().toString();
        request.setAttribute(LOG_ID, uuid);

        // @RequestMapping: HandlerMethod
        // 정적 리소스: ResourceHttpRequestMethod
        if (handler instanceof HandlerMethod) {
            // 호출할 컨트롤러 메서드의 모든 정보가 포함되어 있다.
            HandlerMethod hm = (HandlerMethod) handler;
        }

        log.info("[{}][{}] LogInterceptor preHandle", requestURI, uuid);
        return true;
    }

    @Override
    public void postHandle(
            HttpServletRequest request,
            HttpServletResponse response,
            Object handler,
            ModelAndView modelAndView
    ) throws Exception {
        String requestURI = request.getRequestURI();
        String uuid = (String) request.getAttribute(LOG_ID);

        log.info("[{}][{}] LogInterceptor postHandle", requestURI, uuid);
    }

    @Override
    public void afterCompletion(
            HttpServletRequest request,
            HttpServletResponse response,
            Object handler,
            Exception ex
    ) throws Exception {
        String requestURI = request.getRequestURI();
        String uuid = (String) request.getAttribute(LOG_ID);

        log.info("[{}][{}] LogInterceptor afterComplete", requestURI, uuid);

        if (ex != null) {
            log.error("LogInterceptor afterComplete Error: ", ex);
            ex.printStackTrace();
        }
    }
}

LoginCheckInterceptor

@Slf4j
public class LoginCheckInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(
            HttpServletRequest request,
            HttpServletResponse response,
            Object handler
    ) throws Exception {
        String requestURI = request.getRequestURI();
        String uuid = (String) request.getAttribute(LogInterceptor.LOG_ID);
        log.info("[{}][{}] LoginCheckInterceptor preHandle", requestURI, uuid);

        HttpSession session = request.getSession();
        if (session == null || session.getAttribute(SessionConst.LOGIN_MEMBER) == null) {
            log.info("미인증 사용자 요청 {}", requestURI);
            response.sendRedirect("/login?redirectURL=" + requestURI);
            return false;
        }

        return true;
    }

    @Override
    public void postHandle(
            HttpServletRequest request,
            HttpServletResponse response,
            Object handler,
            ModelAndView modelAndView
    ) throws Exception {
        String requestURI = request.getRequestURI();
        String uuid = (String) request.getAttribute(LogInterceptor.LOG_ID);

        log.info("[{}][{}] LoginCheckInterceptor postHandle", requestURI, uuid);
    }

    @Override
    public void afterCompletion(
            HttpServletRequest request,
            HttpServletResponse response,
            Object handler,
            Exception ex
    ) throws Exception {
        String requestURI = request.getRequestURI();
        String uuid = (String) request.getAttribute(LogInterceptor.LOG_ID);

        log.info("[{}][{}] LoginCheckInterceptor afterCompletion", requestURI, uuid);
    }
}

InterceptorConfig

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LogInterceptor())
                .order(1)
                .addPathPatterns("/**") // 모두 허용
                .excludePathPatterns("/css/**", "/*.ico", "/error"); // BlackList

        registry.addInterceptor(new LoginCheckInterceptor())
                .order(2)
                .addPathPatterns("/**")
                .excludePathPatterns(
                        "/", "/members/css", "/login",
                        "/logout", "/css/**", "*.ico", "/error"
                );
    }
}

결과 1 - 미인증 사용자 요청

// /items 요청
[/items][45e50a37-57a0-4298-b50e-e42141005426] LogInterceptor preHandle
[/items][45e50a37-57a0-4298-b50e-e42141005426] LoginCheckInterceptor preHandle
미인증 사용자 요청 /items
[/items][45e50a37-57a0-4298-b50e-e42141005426] LogInterceptor afterComplete

// Redirect - /login
[/login][18f052ab-b849-4690-83ec-43866660f570] LogInterceptor preHandle
[/login][18f052ab-b849-4690-83ec-43866660f570] LogInterceptor postHandle
[/login][18f052ab-b849-4690-83ec-43866660f570] LogInterceptor afterComplete

로그상으로 LoginCheckInterceptor의 afterComplete가 누락되었습니다.

결과2 - 정상 처리

// /login 요청
[/login][19bad338-e02d-4bbe-8b3a-5dfc55ad4428] LogInterceptor preHandle
LoginService: 'test', 'test!'
login? Member(id=1, loginId=test, name=테스터, password=test!)
[/login][19bad338-e02d-4bbe-8b3a-5dfc55ad4428] LogInterceptor postHandle
[/login][19bad338-e02d-4bbe-8b3a-5dfc55ad4428] LogInterceptor afterComplete

// Redirect - /items
[/items][679dc279-ff3a-4ee3-a424-26b18ac8dbbd] LogInterceptor preHandle
[/items][679dc279-ff3a-4ee3-a424-26b18ac8dbbd] LoginCheckInterceptor preHandle
[/items][679dc279-ff3a-4ee3-a424-26b18ac8dbbd] LoginCheckInterceptor postHandle
[/items][679dc279-ff3a-4ee3-a424-26b18ac8dbbd] LogInterceptor postHandle
[/items][679dc279-ff3a-4ee3-a424-26b18ac8dbbd] LoginCheckInterceptor afterCompletion
[/items][679dc279-ff3a-4ee3-a424-26b18ac8dbbd] LogInterceptor afterComplete

preHandle은 order의 순위대로 로그가 찍히는데, postHandle과 afterCompletion의 경우 order의 순위와 반대로 호출이 됩니다.

혹시 위 2개의 결과에 대한 이유를 설명해주실 수 있을까요..? 그냥 로직때문에 그런 것인지 궁금합니다.