Moongeul · gogori6565 · Mar 18, 2026 · Mar 18, 2026 · Mar 18, 2026
diff --git a/src/main/java/com/moongeul/backend/api/book/entity/Book.java b/src/main/java/com/moongeul/backend/api/book/entity/Book.java
@@ -39,5 +39,9 @@ public void update(String title, String author, String bookImage, String publish
         this.description = description;
         this.pubdate = pubdate;
     }
-}
 
+    public void updateRatingStats(Double ratingAverage, Integer ratingCount) {
+        this.ratingAverage = ratingAverage;
+        this.ratingCount = ratingCount;
+    }
+}
diff --git a/src/main/java/com/moongeul/backend/api/bookshelf/controller/DoneReadBookshelfController.java b/src/main/java/com/moongeul/backend/api/bookshelf/controller/DoneReadBookshelfController.java
@@ -47,7 +47,7 @@ public ResponseEntity<ApiResponse<DoneReadBookshelfResponseDTO>> getDoneReadBook
             @RequestParam(required = false, defaultValue = "10") @Min(value = 1, message = "한 페이지당 개수는 1 이상이어야 합니다.") Integer size) {
 
         DoneReadBookshelfResponseDTO doneReadBookshelfResponseDTO =
-                doneReadBookshelfService.getDoneReadBooks(userDetails.getUsername(), userId, page, size);
+                doneReadBookshelfService.getDoneReadBooks(resolveUsername(userDetails), userId, page, size);
         return ApiResponse.success(SuccessStatus.GET_DONE_READ_BOOKS_SUCCESS, doneReadBookshelfResponseDTO);
     }
 
@@ -71,7 +71,7 @@ public ResponseEntity<ApiResponse<DoneReadBookPostListResponseDTO>> getDoneReadB
             @RequestParam(defaultValue = "10") @Min(value = 1, message = "한 페이지당 개수는 1 이상이어야 합니다.") Integer size) {
 
         DoneReadBookPostListResponseDTO doneReadBookPostListResponseDTO =
-                doneReadBookshelfService.getDoneReadBookPosts(userDetails.getUsername(), userId, isbn, page, size);
+                doneReadBookshelfService.getDoneReadBookPosts(resolveUsername(userDetails), userId, isbn, page, size);
         return ApiResponse.success(SuccessStatus.GET_DONE_READ_BOOK_POSTS_SUCCESS, doneReadBookPostListResponseDTO);
     }
 
@@ -94,7 +94,7 @@ public ResponseEntity<ApiResponse<DoneReadCalendarResponseDTO>> getDoneReadCalen
             @RequestParam @Min(value = 1, message = "월은 1 이상이어야 합니다.") @Max(value = 12, message = "월은 12 이하여야 합니다.") Integer month) {
 
         DoneReadCalendarResponseDTO doneReadCalendar = doneReadBookshelfService.getDoneReadCalendar(
-                userDetails.getUsername(), userId, year, month);
+                resolveUsername(userDetails), userId, year, month);
         return ApiResponse.success(SuccessStatus.GET_DONE_READ_CALENDAR_SUCCESS, doneReadCalendar);
     }
 
@@ -113,7 +113,7 @@ public ResponseEntity<ApiResponse<DoneReadRatingSummaryResponseDTO>> getDoneRead
             @RequestParam(required = false) Long userId) {
 
         DoneReadRatingSummaryResponseDTO doneReadRatingSummaryResponseDTO =
-                doneReadBookshelfService.getDoneReadRatingSummary(userDetails.getUsername(), userId);
+                doneReadBookshelfService.getDoneReadRatingSummary(resolveUsername(userDetails), userId);
         return ApiResponse.success(SuccessStatus.GET_DONE_READ_RATING_SUMMARY_SUCCESS, doneReadRatingSummaryResponseDTO);
     }
 
@@ -144,7 +144,11 @@ public ResponseEntity<ApiResponse<CategoryPostListResponseDTO>> getDoneReadRatin
             @RequestParam(defaultValue = "10") @Min(value = 1, message = "한 페이지당 개수는 1 이상이어야 합니다.") Integer size) {
 
         CategoryPostListResponseDTO categoryPostListResponseDTO =
-                doneReadBookshelfService.getDoneReadRatingDetail(userDetails.getUsername(), userId, range, sortBy, page, size);
+                doneReadBookshelfService.getDoneReadRatingDetail(resolveUsername(userDetails), userId, range, sortBy, page, size);
         return ApiResponse.success(SuccessStatus.GET_DONE_READ_RATING_DETAIL_SUCCESS, categoryPostListResponseDTO);
     }
+
+    private String resolveUsername(UserDetails userDetails) {
+        return (userDetails != null) ? userDetails.getUsername() : "anonymousUser";
+    }
 }
diff --git a/src/main/java/com/moongeul/backend/api/bookshelf/service/DoneReadBookshelfService.java b/src/main/java/com/moongeul/backend/api/bookshelf/service/DoneReadBookshelfService.java
@@ -203,7 +203,7 @@ public DoneReadRatingSummaryResponseDTO getDoneReadRatingSummary(String email, L
     // 읽은 책별 기록 리스트 조회
     @Transactional(readOnly = true)
     public DoneReadBookPostListResponseDTO getDoneReadBookPosts(String email, Long userId, String isbn, Integer page, Integer size) {
-        Member currentMember = getCurrentMember(email);
+        Member currentMember = getCurrentMemberOrNull(email);
         Member targetMember = getTargetMember(currentMember, userId);
         Book book = bookRepository.findByIsbn(isbn)
                 .orElseThrow(() -> new NotFoundException(ErrorStatus.BOOK_NOTFOUND_EXCEPTION.getMessage()));
@@ -230,7 +230,7 @@ public DoneReadBookPostListResponseDTO getDoneReadBookPosts(String email, Long u
     // 읽은 책 별점 구간 상세 조회
     @Transactional(readOnly = true)
     public CategoryPostListResponseDTO getDoneReadRatingDetail(String email, Long userId, String range, String sortBy, Integer page, Integer size) {
-        Member currentMember = getCurrentMember(email);
+        Member currentMember = getCurrentMemberOrNull(email);
         Member targetMember = getTargetMember(currentMember, userId);
 
         int rangeIndex = findRangeIndex(range);
@@ -380,27 +380,36 @@ private int findRangeIndex(String range) {
     }
 
     private Member getTargetMember(String email, Long userId) {
-        Member currentMember = getCurrentMember(email);
+        Member currentMember = getCurrentMemberOrNull(email);
         return getTargetMember(currentMember, userId);
     }
 
-    private Member getCurrentMember(String email) {
+    private Member getCurrentMemberOrNull(String email) {
+        if (email == null || "anonymousUser".equals(email)) {
+            return null;
+        }
+
         return memberRepository.findByEmail(email)
                 .orElseThrow(() -> new NotFoundException(ErrorStatus.USER_NOTFOUND_EXCEPTION.getMessage()));
     }
 
     private Member getTargetMember(Member currentMember, Long userId) {
-        Member targetMember = (userId == null)
-                ? currentMember
-                : memberRepository.findById(userId)
-                .orElseThrow(() -> new NotFoundException(ErrorStatus.USER_NOTFOUND_EXCEPTION.getMessage()));
+        Member targetMember;
+        if (userId != null) {
+            targetMember = memberRepository.findById(userId)
+                    .orElseThrow(() -> new NotFoundException(ErrorStatus.USER_NOTFOUND_EXCEPTION.getMessage()));
+        } else if (currentMember != null) {
+            targetMember = currentMember;
+        } else {
+            throw new NotFoundException(ErrorStatus.USER_NOTFOUND_EXCEPTION.getMessage());
+        }
 
         validatePrivacyAccess(currentMember, targetMember);
         return targetMember;
     }
 
     private void validatePrivacyAccess(Member currentMember, Member targetMember) {
-        if (currentMember.getId().equals(targetMember.getId())) {
+        if (currentMember != null && currentMember.getId().equals(targetMember.getId())) {
             return;
         }
 
@@ -415,6 +424,10 @@ private void validatePrivacyAccess(Member currentMember, Member targetMember) {
         }
 
         if (privacyLevel == PrivacyLevel.FOLLOWER_ONLY) {
+            if (currentMember == null) {
+                throw new ForbiddenException(ErrorStatus.PRIVACY_FORBIDDEN_EXCEPTION.getMessage());
+            }
+
             FollowStatus status = followRepository.findByFollowingIdAndFollowerId(targetMember.getId(), currentMember.getId())
                     .map(Follow::getFollowStatus)
                     .orElse(FollowStatus.NONE);

diff --git a/src/main/java/com/moongeul/backend/api/member/controller/MemberController.java b/src/main/java/com/moongeul/backend/api/member/controller/MemberController.java
@@ -106,7 +106,7 @@ public ResponseEntity<ApiResponse<LoginResponseDTO>> loginWithKakao(@Valid @Requ
     public ResponseEntity<ApiResponse<UserInfoDTO>> getUserInfo(
             @AuthenticationPrincipal UserDetails userDetails,
             @RequestParam(required = false) Long userId){
-        UserInfoDTO response = memberService.getUserInfo(userDetails.getUsername(), userId);
+        UserInfoDTO response = memberService.getUserInfo(resolveUsername(userDetails), userId);
         return ApiResponse.success(SuccessStatus.GET_USERINFO_SUCCESS, response);
     }
 
@@ -187,7 +187,7 @@ public ResponseEntity<ApiResponse<Void>> withdraw(@AuthenticationPrincipal UserD
     public ResponseEntity<ApiResponse<PostStatsResponseDTO>> getPostStats(
             @AuthenticationPrincipal UserDetails userDetails,
             @RequestParam(required = false) Long userId){
-        PostStatsResponseDTO response = memberService.getPostStats(userDetails.getUsername(), userId);
+        PostStatsResponseDTO response = memberService.getPostStats(resolveUsername(userDetails), userId);
         return ApiResponse.success(SuccessStatus.GET_POST_STATS_SUCCESS, response);
     }
 
@@ -217,7 +217,7 @@ public ResponseEntity<ApiResponse<CategoryPostListResponseDTO>> getCategoryPostL
             @RequestParam(defaultValue = "10") Integer size) {
 
         CategoryPostListResponseDTO categoryPostListResponseDTO =
-                memberService.getCategoryPostList(userDetails.getUsername(), userId, categoryId, sortBy, page, size);
+                memberService.getCategoryPostList(resolveUsername(userDetails), userId, categoryId, sortBy, page, size);
         return ApiResponse.success(SuccessStatus.GET_CATEGORY_POST_LIST_SUCCESS, categoryPostListResponseDTO);
     }
 
@@ -245,7 +245,7 @@ public ResponseEntity<ApiResponse<CategoryPostListResponseDTO>> getLikedPostList
             @RequestParam(defaultValue = "10") Integer size) {
 
         CategoryPostListResponseDTO likedPostListResponseDTO =
-                memberService.getLikedPostList(userDetails.getUsername(), userId, sortBy, page, size);
+                memberService.getLikedPostList(resolveUsername(userDetails), userId, sortBy, page, size);
         return ApiResponse.success(SuccessStatus.GET_LIKED_POST_LIST_SUCCESS, likedPostListResponseDTO);
     }
 
@@ -265,10 +265,14 @@ public ResponseEntity<ApiResponse<QuestionListResponseDTO>> getMyQuestionList(
             @RequestParam(defaultValue = "10") Integer size) {
 
         QuestionListResponseDTO questionListResponseDTO =
-                questionService.getMyQuestionList(page, size, userDetails.getUsername(), userId);
+                questionService.getMyQuestionList(page, size, resolveUsername(userDetails), userId);
         return ApiResponse.success(SuccessStatus.GET_MY_QUESTION_LIST_SUCCESS, questionListResponseDTO);
     }
 
+    private String resolveUsername(UserDetails userDetails) {
+        return (userDetails != null) ? userDetails.getUsername() : "anonymousUser";
+    }
+
     /*
     *
     * 팔로잉/팔로우 API

diff --git a/src/main/java/com/moongeul/backend/api/member/service/MemberService.java b/src/main/java/com/moongeul/backend/api/member/service/MemberService.java
@@ -169,13 +169,10 @@ private Member signUp(String socialId, String email, String name, String picture
     @Transactional(readOnly = true)
     public UserInfoDTO getUserInfo(String email, Long userId){
 
-        Member currentMember = getMemberByEmail(email);
+        Member currentMember = getCurrentMemberOrNull(email);
 
         // userId가 null이면 본인 정보 조회, 있으면 타 사용자 조회
-        Member member = (userId == null)
-                ? currentMember
-                : memberRepository.findById(userId)
-                .orElseThrow(() -> new NotFoundException(ErrorStatus.USER_NOTFOUND_EXCEPTION.getMessage()));
+        Member member = getTargetMember(currentMember, userId);
 
         // 팔로워 수 계산 (나를 팔로우하는 사람들 중 승인된 경우)
         int followerCount = followRepository.findByFollowers(member.getId()).size();
@@ -185,7 +182,7 @@ public UserInfoDTO getUserInfo(String email, Long userId){
 
         // 내가 해당 사용자를 팔로우했는지 여부
         FollowStatus myFollowStatus = FollowStatus.NONE;
-        if (!currentMember.getId().equals(member.getId())) {
+        if (currentMember != null && !currentMember.getId().equals(member.getId())) {
             myFollowStatus = followRepository.findByFollowingIdAndFollowerId(member.getId(), currentMember.getId())
                     .map(Follow::getFollowStatus)
                     .orElse(FollowStatus.NONE);
@@ -285,11 +282,8 @@ public void withdraw(String email, WithdrawalRequestDTO withdrawalRequestDTO) {
     @Transactional(readOnly = true)
     public PostStatsResponseDTO getPostStats(String email, Long userId) {
 
-        Member currentMember = getMemberByEmail(email);
-        Member targetMember = (userId == null)
-                ? currentMember
-                : memberRepository.findById(userId)
-                .orElseThrow(() -> new NotFoundException(ErrorStatus.USER_NOTFOUND_EXCEPTION.getMessage()));
+        Member currentMember = getCurrentMemberOrNull(email);
+        Member targetMember = getTargetMember(currentMember, userId);
 
         validatePrivacyAccess(currentMember, targetMember);
 
@@ -436,11 +430,8 @@ public void updateProfileImage(String email, MultipartFile profileImage) {
     @Transactional(readOnly = true)
     public CategoryPostListResponseDTO getCategoryPostList(String email, Long userId, Long categoryId, String sortBy, Integer page, Integer size) {
 
-        Member currentMember = getMemberByEmail(email);
-        Member targetMember = (userId == null)
-                ? currentMember
-                : memberRepository.findById(userId)
-                .orElseThrow(() -> new NotFoundException(ErrorStatus.USER_NOTFOUND_EXCEPTION.getMessage()));
+        Member currentMember = getCurrentMemberOrNull(email);
+        Member targetMember = getTargetMember(currentMember, userId);
 
         validatePrivacyAccess(currentMember, targetMember);
 
@@ -507,11 +498,8 @@ public CategoryPostListResponseDTO getCategoryPostList(String email, Long userId
     @Transactional(readOnly = true)
     public CategoryPostListResponseDTO getLikedPostList(String email, Long userId, String sortBy, Integer page, Integer size) {
 
-        Member currentMember = getMemberByEmail(email);
-        Member targetMember = (userId == null)
-                ? currentMember
-                : memberRepository.findById(userId)
-                .orElseThrow(() -> new NotFoundException(ErrorStatus.USER_NOTFOUND_EXCEPTION.getMessage()));
+        Member currentMember = getCurrentMemberOrNull(email);
+        Member targetMember = getTargetMember(currentMember, userId);
 
         validatePrivacyAccess(currentMember, targetMember);
 
@@ -627,7 +615,7 @@ private PostDTO.MyLikesStatus convertToMyLikesStatus(Member currentMember, Long
     }
 
     private void validatePrivacyAccess(Member currentMember, Member targetMember) {
-        if (currentMember.getId().equals(targetMember.getId())) {
+        if (currentMember != null && currentMember.getId().equals(targetMember.getId())) {
             return;
         }
 
@@ -642,6 +630,10 @@ private void validatePrivacyAccess(Member currentMember, Member targetMember) {
         }
 
         if (privacyLevel == PrivacyLevel.FOLLOWER_ONLY) {
+            if (currentMember == null) {
+                throw new ForbiddenException(ErrorStatus.PRIVACY_FORBIDDEN_EXCEPTION.getMessage());
+            }
+
             FollowStatus status = followRepository.findByFollowingIdAndFollowerId(targetMember.getId(), currentMember.getId())
                     .map(Follow::getFollowStatus)
                     .orElse(FollowStatus.NONE);
@@ -652,6 +644,27 @@ private void validatePrivacyAccess(Member currentMember, Member targetMember) {
         }
     }
 
+    private Member getCurrentMemberOrNull(String email) {
+        if (email == null || "anonymousUser".equals(email)) {
+            return null;
+        }
+
+        return getMemberByEmail(email);
+    }
+
+    private Member getTargetMember(Member currentMember, Long userId) {
+        if (userId != null) {
+            return memberRepository.findById(userId)
+                    .orElseThrow(() -> new NotFoundException(ErrorStatus.USER_NOTFOUND_EXCEPTION.getMessage()));
+        }
+
+        if (currentMember != null) {
+            return currentMember;
+        }
+
+        throw new NotFoundException(ErrorStatus.USER_NOTFOUND_EXCEPTION.getMessage());
+    }
+
     /* 스토리 보관함 조회 API */
     @Transactional(readOnly = true)
     public MyStoryResponseDTO getMyStories(String email, Integer page, Integer size) {

diff --git a/src/main/java/com/moongeul/backend/api/post/repository/PostRepository.java b/src/main/java/com/moongeul/backend/api/post/repository/PostRepository.java
@@ -142,6 +142,11 @@ List<Post> findCalendarPostsByMemberAndReadDateBetweenOrderByReadDateAscCreatedA
     @Query("SELECT p.rating FROM Post p WHERE p.member = :member AND p.rating IS NOT NULL")
     List<Double> findRatingsByMember(@Param("member") Member member);
 
+    @Query("SELECT COALESCE(AVG(p.rating), 0.0) FROM Post p WHERE p.book = :book AND p.rating IS NOT NULL")
+    Double findAverageRatingByBook(@Param("book") Book book);
+
+    long countByBookAndRatingIsNotNull(Book book);
+
     Page<Post> findByMemberAndRatingBetween(Member member, Double startRating, Double endRating, Pageable pageable);
 
     @Query("SELECT p FROM Post p WHERE p.member = :member AND p.book.isbn = :isbn ORDER BY p.createdAt DESC")

diff --git a/src/main/java/com/moongeul/backend/api/post/service/PostService.java b/src/main/java/com/moongeul/backend/api/post/service/PostService.java
@@ -103,6 +103,8 @@ public PostIdResponseDTO createPost(PostRequestDTO postRequestDTO, String email)
             doneReadBookshelfRepository.save(doneReadBookshelf);
         }
 
+        updateBookRatingStats(book);
+
         return PostIdResponseDTO.builder()
                 .postId(savedPost.getId())
                 .build();
@@ -284,8 +286,8 @@ private PostDTO.MyLikesStatus convertToMyLikesStatus(String email, Long postId){
     public PostIdResponseDTO updatePost(Long postId, String email, PostRequestDTO postRequestDTO){
 
         Post post = getPost(postId);
+        Book targetBook = post.getBook();
         Category category = getCategory(postRequestDTO.getCategoryId());
-        Book book = getBook(post.getBook().getIsbn());
 
         // 예외처리: 수정하는 사람과 게시글 주인이 같은지 확인 (본인의 게시글인지)
         if (!post.getMember().getEmail().equals(email)) {
@@ -320,9 +322,11 @@ public PostIdResponseDTO updatePost(Long postId, String email, PostRequestDTO po
                 postRequestDTO.getContent(),
                 postRequestDTO.getPostVisibility(),
                 category,
-                book
+                targetBook
         );
 
+        updateBookRatingStats(targetBook);
+
         return PostIdResponseDTO.builder()
                 .postId(post.getId())
                 .build();
@@ -333,6 +337,7 @@ public PostIdResponseDTO updatePost(Long postId, String email, PostRequestDTO po
     public void deletePost(Long postId, String email){
 
         Post post = getPost(postId);
+        Book book = post.getBook();
 
         // 예외처리: 수정하는 사람과 게시글 주인이 같은지 확인 (본인의 게시글인지)
         if (!post.getMember().getEmail().equals(email)) {
@@ -344,6 +349,8 @@ public void deletePost(Long postId, String email){
 
         // 게시글 삭제
         postRepository.delete(post);
+
+        updateBookRatingStats(book);
     }
 
 
@@ -415,6 +422,15 @@ private void decrementLikeCount(Post post, LikeType likeType) {
         }
     }
 
+    // 책 평점 수정 메서드
+    private void updateBookRatingStats(Book book) {
+        long ratingCount = postRepository.countByBookAndRatingIsNotNull(book);
+        Double ratingAverage = postRepository.findAverageRatingByBook(book);
+
+        double finalAverage = (ratingAverage == null) ? 0.0 : Math.round(ratingAverage * 10) / 10.0;
+        book.updateRatingStats(finalAverage, (int) ratingCount);
+    }
+
     /*
      * 추천
      */