refactor : 게시글 리스트 조회시 발생하던 오류 제거하는 코드 리펙토링

.gitignore

@@ -36,7 +36,7 @@ out/
 ### VS Code ###
 .vscode/
 
-/src/main/resources/*.env
+*.env
 *.yml
 
 /src/main/generated/

build.gradle

@@ -30,6 +30,7 @@ dependencies {
 	implementation 'org.springframework.boot:spring-boot-starter-oauth2-client'
 	implementation 'org.springframework.boot:spring-boot-starter-webflux'
 	implementation 'com.fasterxml.jackson.core:jackson-databind'
+	implementation 'org.springframework.boot:spring-boot-starter-validation'
 
 	compileOnly 'org.projectlombok:lombok'
 	runtimeOnly 'com.mysql:mysql-connector-j'

src/main/java/naughty/tuzamate/domain/post/controller/PostController.java

@@ -49,7 +49,7 @@ public CustomResponse<PostResDTO.PostPreviewDTO> getPost(@PathVariable Long post
     public CustomResponse<PostResDTO.PostPreviewListDTO> getPostList(
             @PathVariable BoardType boardType,
             @RequestParam(required = false) Long cursor,
-            @RequestParam(defaultValue = "10") @Max(30) int size) {
+            @RequestParam(defaultValue = "10") @Max(10) int size) {
         PostResDTO.PostPreviewListDTO resDTO = postQueryService.getPostList(boardType, cursor, size);
 
         return CustomResponse.onSuccess(GeneralSuccessCode.OK, resDTO);

src/main/java/naughty/tuzamate/domain/post/converter/PostConverter.java

@@ -9,6 +9,7 @@
 import naughty.tuzamate.domain.user.entity.User;
 
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 @NoArgsConstructor(access = AccessLevel.PRIVATE)

src/main/java/naughty/tuzamate/domain/post/service/query/PostQueryServiceImpl.java

@@ -9,6 +9,7 @@
 import naughty.tuzamate.global.error.GeneralErrorCode;
 import naughty.tuzamate.global.error.exception.CustomException;
 import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Slice;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
@@ -36,20 +37,31 @@ public PostResDTO.PostPreviewDTO getPost(Long postId) {
     @Override
     @Transactional(readOnly = true)
     public PostResDTO.PostPreviewListDTO getPostList(BoardType boardType, Long cursor, int size) {
-        PageRequest pr = PageRequest.of(0, size);
-        Slice<Post> slice = postRepository.findByBoardTypeAndCursor(boardType, cursor, pr);
+        cursor = normalizeCursor(cursor);
+        size = normalizeSize(size);
 
-        List<PostResDTO.PostPreviewDTO> previews = slice.getContent()
-                .stream()
+        Pageable pageable = PageRequest.of(0, size);
+        Slice<Post> slice = postRepository.findByBoardTypeAndCursor(boardType, cursor, pageable);
+
+        List<PostResDTO.PostPreviewDTO> previews = slice.stream()
                 .map(PostConverter::toPostPreviewDTO)
                 .toList();
 
-        Long nextCursor = slice.hasNext() ? previews.get(previews.size() - 1).id() : null;
+        Long nextCursor = (slice.hasNext() && !previews.isEmpty()) ? previews.get(previews.size() - 1).id() : null;
 
         return PostResDTO.PostPreviewListDTO.builder()
                 .postPreviewDTOList(previews)
                 .nextCursor(nextCursor)
                 .hasNext(slice.hasNext())
                 .build();
     }
+
+    private Long normalizeCursor(Long cursor) {
+        return (cursor == null || cursor == 0) ? Long.MAX_VALUE : cursor;
+    }
+
+    // 요청 사이즈가 1보다 작으면 기본값 10, 10보다 크면 최대값 10으로 제한
+    private int normalizeSize(int size) {
+        return (size < 1 || size > 10) ? 10 : size;
+    }
 }

src/main/java/naughty/tuzamate/global/config/FireBaseConfig.java

@@ -9,30 +9,43 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.Resource;
+
 import java.io.FileInputStream;
 
 import java.io.IOException;
+import java.io.InputStream;
 
 @Slf4j
 @Configuration
 public class FireBaseConfig {
 
+    // String 대신 Resource 타입으로 주입받음
     @Value("${firebase.service-account.path}")
-    private String SERVICE_ACCOUNT_PATH;
+    private Resource serviceAccountResource;
 
     @Bean
     public FirebaseApp firebaseApp() {
-        try (FileInputStream serviceAccount = new FileInputStream(SERVICE_ACCOUNT_PATH)) {
+        try {
+            // 주입받은 Resource에서 바로 InputStream을 얻음
+            InputStream serviceAccount = serviceAccountResource.getInputStream();
+
             FirebaseOptions options = FirebaseOptions.builder()
                     .setCredentials(GoogleCredentials.fromStream(serviceAccount))
                     .build();
 
-            log.info("Successfully initialized firebase app");
-            return FirebaseApp.initializeApp(options);
+            // 앱이 이미 초기화되었는지 확인 (중복 초기화 방지)
+            if (FirebaseApp.getApps().isEmpty()) {
+                log.info("Successfully initialized firebase app");
+                return FirebaseApp.initializeApp(options);
+            } else {
+                return FirebaseApp.getInstance();
+            }
 
         } catch (IOException exception) {
             log.error("Fail to initialize firebase app: {}", exception.getMessage(), exception);
-            return null;
+            // 초기화 실패 시 null 대신 예외를 던져서 애플리케이션이 문제를 인지하게 하는 것이 더 좋습니다.
+            throw new RuntimeException("Failed to initialize Firebase app.", exception);
         }
     }