[BE] Product 엔티티에 reviewCount 필드 추가 (#616)

* feat: Product 엔티티의 필드에 reviewCount 추가

* feat: Review 작성시 product의 reviewCount 1증가 기능 구현

* refactor: Product의 ReviewCount 필드의 자료형을 AtomicLong으로 수정

* refactor: AtomicLong 관련 set 제거

backend/src/main/java/com/funeat/product/domain/Product.java

@@ -3,6 +3,8 @@
 import com.funeat.member.domain.bookmark.ProductBookmark;
 import com.funeat.review.domain.Review;
 import java.util.List;
+import java.util.Objects;
+import java.util.concurrent.atomic.AtomicLong;
 import javax.persistence.Entity;
 import javax.persistence.FetchType;
 import javax.persistence.GeneratedValue;
@@ -42,6 +44,8 @@ public class Product {
     @OneToMany(mappedBy = "product")
     private List<ProductBookmark> productBookmarks;
 
+    private AtomicLong reviewCount = new AtomicLong(0);
+
     protected Product() {
     }
 
@@ -106,4 +110,12 @@ public Double getAverageRating() {
     public Category getCategory() {
         return category;
     }
+
+    public Long getReviewCount() {
+        return reviewCount.get();
+    }
+
+    public void addReviewCount() {
+        reviewCount.incrementAndGet();
+    }
 }

backend/src/main/java/com/funeat/review/application/ReviewService.java

@@ -95,6 +95,7 @@ public void create(final Long productId, final Long memberId, final MultipartFil
         final Long countByProduct = reviewRepository.countByProduct(findProduct);
 
         findProduct.updateAverageRating(savedReview.getRating(), countByProduct);
+        findProduct.addReviewCount();
         reviewTagRepository.saveAll(reviewTags);
     }