♻️Refactor: 게시글 좋아요 기능 추가 및 댓글 수, 좋아요 수 조회 추가

src/main/java/com/sku/refit/domain/post/controller/PostController.java

@@ -48,6 +48,11 @@ ResponseEntity<BaseResponse<PostDetailResponse>> createPost(
           @RequestPart(value = "imageList", required = false)
           List<MultipartFile> imageList);
 
+  @PostMapping("/{postId}/like")
+  @Operation(summary = "게시글 좋아요 토글", description = "게시글 좋아요를 등록/취소합니다.")
+  ResponseEntity<BaseResponse<Boolean>> togglePostLike(
+      @Parameter(description = "게시글 ID", example = "1") @PathVariable Long postId);
+
   @GetMapping("/admin")
   @Operation(summary = "[관리자] 게시글 전체 조회", description = "전체 게시글 리스트를 조회합니다.")
   ResponseEntity<BaseResponse<List<PostDetailResponse>>> getAllPosts();

src/main/java/com/sku/refit/domain/post/controller/PostControllerImpl.java

@@ -8,6 +8,7 @@
 import jakarta.validation.Valid;
 
 import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.multipart.MultipartFile;
 
@@ -18,11 +19,9 @@
 import com.sku.refit.global.response.BaseResponse;
 
 import lombok.RequiredArgsConstructor;
-import lombok.extern.slf4j.Slf4j;
 
 @RestController
 @RequiredArgsConstructor
-@Slf4j
 public class PostControllerImpl implements PostController {
 
   private final PostService postService;
@@ -35,6 +34,13 @@ public ResponseEntity<BaseResponse<PostDetailResponse>> createPost(
     return ResponseEntity.ok(BaseResponse.success(response));
   }
 
+  @Override
+  public ResponseEntity<BaseResponse<Boolean>> togglePostLike(@PathVariable Long postId) {
+
+    boolean liked = postService.togglePostLike(postId);
+    return ResponseEntity.ok(BaseResponse.success(liked));
+  }
+
   @Override
   public ResponseEntity<BaseResponse<List<PostDetailResponse>>> getAllPosts() {
 

src/main/java/com/sku/refit/domain/post/dto/response/PostDetailResponse.java

@@ -32,6 +32,12 @@ public class PostDetailResponse {
   @Schema(description = "게시글 조회수", example = "100")
   private Long views;
 
+  @Schema(description = "게시글 좋아요수", example = "100")
+  private Long likes;
+
+  @Schema(description = "게시글 댓글수", example = "100")
+  private Long comments;
+
   @Schema(description = "게시글 작성 시간", example = "2025-12-03T14:37:17")
   private LocalDateTime createdAt;
 
@@ -41,6 +47,9 @@ public class PostDetailResponse {
   @Schema(description = "작성자 본인 여부", example = "true")
   private Boolean isAuthor;
 
+  @Schema(description = "내가 좋아요를 눌렀는지 여부", example = "true")
+  private Boolean isLiked;
+
   @Schema(description = "이미지 URL 리스트")
   private List<String> imageUrlList;
 

src/main/java/com/sku/refit/domain/post/entity/PostLike.java

@@ -0,0 +1,34 @@
+/* 
+ * Copyright (c) SKU 다시입을Lab 
+ */
+package com.sku.refit.domain.post.entity;
+
+import jakarta.persistence.*;
+
+import com.sku.refit.domain.user.entity.User;
+import com.sku.refit.global.common.BaseTimeEntity;
+
+import lombok.*;
+
+@Entity
+@Getter
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@AllArgsConstructor
+@Builder
+@Table(
+    name = "post_like",
+    uniqueConstraints = {@UniqueConstraint(columnNames = {"post_id", "user_id"})})
+public class PostLike extends BaseTimeEntity {
+
+  @Id
+  @GeneratedValue(strategy = GenerationType.IDENTITY)
+  private Long id;
+
+  @ManyToOne(fetch = FetchType.LAZY)
+  @JoinColumn(name = "post_id", nullable = false)
+  private Post post;
+
+  @ManyToOne(fetch = FetchType.LAZY)
+  @JoinColumn(name = "user_id", nullable = false)
+  private User user;
+}

src/main/java/com/sku/refit/domain/post/mapper/PostMapper.java

@@ -29,16 +29,20 @@ public Post toPost(
         .build();
   }
 
-  public PostDetailResponse toDetailResponse(Post post, User user) {
+  public PostDetailResponse toDetailResponse(
+      Post post, Long likeCount, Boolean isLiked, User user) {
 
     return PostDetailResponse.builder()
         .postId(post.getId())
         .title(post.getTitle())
         .content(post.getContent())
         .views(post.getViews())
+        .likes(likeCount)
+        .comments((long) post.getCommentList().size())
         .createdAt(post.getCreatedAt())
         .nickname(post.getUser().getNickname())
         .isAuthor(user != null && post.getUser().getUsername().equals(user.getUsername()))
+        .isLiked(isLiked)
         .category(post.getPostCategory())
         .commentIdList(post.getCommentList().stream().map(Comment::getId).toList())
         .build();

src/main/java/com/sku/refit/domain/post/repository/PostLikeRepository.java

@@ -0,0 +1,40 @@
+/* 
+ * Copyright (c) SKU 다시입을Lab 
+ */
+package com.sku.refit.domain.post.repository;
+
+import java.util.List;
+import java.util.Optional;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+
+import com.sku.refit.domain.post.entity.PostLike;
+
+public interface PostLikeRepository extends JpaRepository<PostLike, Long> {
+
+  Optional<PostLike> findByPostIdAndUserId(Long postId, Long userId);
+
+  boolean existsByPostIdAndUserId(Long postId, Long userId);
+
+  long countByPostId(Long postId);
+
+  @Query(
+      """
+  select pl.post.id, count(pl)
+  from PostLike pl
+  where pl.post.id in :postIds
+  group by pl.post.id
+""")
+  List<Object[]> countByPostIds(@Param("postIds") List<Long> postIds);
+
+  @Query(
+      """
+  select pl.post.id
+  from PostLike pl
+  where pl.post.id in :postIds
+    and pl.user.id = :userId
+""")
+  List<Long> findLikedPostIds(@Param("postIds") List<Long> postIds, @Param("userId") Long userId);
+}

src/main/java/com/sku/refit/domain/post/service/PostService.java

@@ -36,6 +36,16 @@ public interface PostService {
    */
   PostDetailResponse createPost(PostRequest request, List<MultipartFile> images);
 
+  /**
+   * 게시글 좋아요를 토글합니다.
+   *
+   * <p>이미 좋아요가 되어 있으면 취소하고, 좋아요가 없으면 새로 생성합니다.
+   *
+   * @param postId 게시글 ID
+   * @return true: 좋아요 상태 / false: 좋아요 취소 상태
+   */
+  boolean togglePostLike(Long postId);
+
   /**
    * 모든 게시글 목록을 조회합니다.
    *

src/main/java/com/sku/refit/domain/post/service/PostServiceImpl.java

@@ -4,7 +4,11 @@
 package com.sku.refit.domain.post.service;
 
 import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Pageable;
@@ -17,8 +21,10 @@
 import com.sku.refit.domain.post.dto.response.PostDetailResponse;
 import com.sku.refit.domain.post.entity.Post;
 import com.sku.refit.domain.post.entity.PostCategory;
+import com.sku.refit.domain.post.entity.PostLike;
 import com.sku.refit.domain.post.exception.PostErrorCode;
 import com.sku.refit.domain.post.mapper.PostMapper;
+import com.sku.refit.domain.post.repository.PostLikeRepository;
 import com.sku.refit.domain.post.repository.PostRepository;
 import com.sku.refit.domain.user.entity.User;
 import com.sku.refit.domain.user.service.UserService;
@@ -37,6 +43,7 @@
 public class PostServiceImpl implements PostService {
 
   private final PostRepository postRepository;
+  private final PostLikeRepository postLikeRepository;
   private final S3Service s3Service;
   private final UserService userService;
   private final PostMapper postMapper;
@@ -72,7 +79,35 @@ public PostDetailResponse createPost(PostRequest request, List<MultipartFile> im
         user.getId(),
         imageUrlList.size());
 
-    return postMapper.toDetailResponse(post, user);
+    return postMapper.toDetailResponse(post, 0L, false, user);
+  }
+
+  @Override
+  @Transactional
+  public boolean togglePostLike(Long postId) {
+
+    User user = userService.getCurrentUser();
+    Post post =
+        postRepository
+            .findById(postId)
+            .orElseThrow(() -> new CustomException(PostErrorCode.POST_NOT_FOUND));
+
+    return postLikeRepository
+        .findByPostIdAndUserId(postId, user.getId())
+        .map(
+            like -> {
+              postLikeRepository.delete(like);
+              log.info("[POST LIKE CANCEL] postId={}, userId={}", postId, user.getId());
+              return false;
+            })
+        .orElseGet(
+            () -> {
+              PostLike postLike = PostLike.builder().post(post).user(user).build();
+
+              postLikeRepository.save(postLike);
+              log.info("[POST LIKE CREATE] postId={}, userId={}", postId, user.getId());
+              return true;
+            });
   }
 
   @Override
@@ -82,9 +117,32 @@ public List<PostDetailResponse> getAllPosts() {
     User user = userService.getCurrentUser();
     List<Post> posts = postRepository.findAll();
 
+    if (posts.isEmpty()) {
+      return List.of();
+    }
+
+    List<Long> postIds = posts.stream().map(Post::getId).toList();
+
+    Map<Long, Long> likeCountMap = new HashMap<>();
+    List<Object[]> likeCounts = postLikeRepository.countByPostIds(postIds);
+    for (Object[] row : likeCounts) {
+      likeCountMap.put((Long) row[0], (Long) row[1]);
+    }
+
+    Set<Long> likedPostIds =
+        new HashSet<>(postLikeRepository.findLikedPostIds(postIds, user.getId()));
+
     log.info("[POST LIST] userId={}, postCount={}", user.getId(), posts.size());
 
-    return posts.stream().map(post -> postMapper.toDetailResponse(post, user)).toList();
+    return posts.stream()
+        .map(
+            post ->
+                postMapper.toDetailResponse(
+                    post,
+                    likeCountMap.getOrDefault(post.getId(), 0L),
+                    likedPostIds.contains(post.getId()),
+                    user))
+        .toList();
   }
 
   @Override
@@ -111,8 +169,33 @@ public InfiniteResponse<PostDetailResponse> getPostsByCategory(
       posts = posts.subList(0, size);
     }
 
+    List<Long> postIds = posts.stream().map(Post::getId).toList();
+
+    Map<Long, Long> likeCountMap = new HashMap<>();
+    if (!postIds.isEmpty()) {
+      List<Object[]> likeCounts = postLikeRepository.countByPostIds(postIds);
+      for (Object[] row : likeCounts) {
+        Long postId = (Long) row[0];
+        Long count = (Long) row[1];
+        likeCountMap.put(postId, count);
+      }
+    }
+
+    Set<Long> likedPostIds =
+        postIds.isEmpty()
+            ? Set.of()
+            : new HashSet<>(postLikeRepository.findLikedPostIds(postIds, user.getId()));
+
     List<PostDetailResponse> postResponseList =
-        posts.stream().map(post -> postMapper.toDetailResponse(post, user)).toList();
+        posts.stream()
+            .map(
+                post ->
+                    postMapper.toDetailResponse(
+                        post,
+                        likeCountMap.getOrDefault(post.getId(), 0L),
+                        likedPostIds.contains(post.getId()),
+                        user))
+            .toList();
 
     Long newLastCursor = posts.isEmpty() ? null : posts.getLast().getId();
 
@@ -142,7 +225,10 @@ public PostDetailResponse getPostById(Long id) {
         user.getId(),
         post.getViews());
 
-    return postMapper.toDetailResponse(post, user);
+    long likeCount = postLikeRepository.countByPostId(post.getId());
+    boolean isLiked = postLikeRepository.existsByPostIdAndUserId(post.getId(), user.getId());
+
+    return postMapper.toDetailResponse(post, likeCount, isLiked, user);
   }
 
   @Override
@@ -190,9 +276,12 @@ public PostDetailResponse updatePost(Long id, PostRequest request, List<Multipar
 
     post.update(request.getTitle(), request.getContent(), newImageUrls);
 
+    long likeCount = postLikeRepository.countByPostId(post.getId());
+    boolean isLiked = postLikeRepository.existsByPostIdAndUserId(post.getId(), user.getId());
+
     log.info("[POST UPDATE COMPLETE] postId={}, userId={}", post.getId(), user.getId());
 
-    return postMapper.toDetailResponse(post, user);
+    return postMapper.toDetailResponse(post, likeCount, isLiked, user);
   }
 
   @Override