[ADD] 과제 커밋, 과제 관련 내용이 이미 전부 작성되어있어서 에러 처리관련 내용 추가

src/main/java/com/cnu/real_coding_server/RealCodingServerApplication.java

@@ -6,8 +6,7 @@
 
 @EnableJpaAuditing
 @SpringBootApplication
-public class RealCodingServerApplication {
-
+public class RealCodingServerApplication
     public static void main(String[] args) {
         SpringApplication.run(RealCodingServerApplication.class, args);
     }

src/main/java/com/cnu/real_coding_server/controller/PostController.java

@@ -42,4 +42,10 @@ public ResponseEntity<Void> deletePost(@PathVariable("postId") Integer postId) {
 
         return ResponseEntity.noContent().build();
     }
+
+    @ExceptionHandler(ResourceNotFoundException.class)
+    @ResponseStatus(HttpStatus.NOT_FOUND)
+    public String handleResourceNotFoundException(ResourceNotFoundException exception) {
+        return exception.getMessage();
+    }
 }

src/main/java/com/cnu/real_coding_server/service/PostService.java

@@ -24,21 +24,25 @@ public List<Post> getPosts() {
     }
 
     public Optional<Post> getPost(Integer postId) {
-        return postRepository.findById(postId);
+        return postRepository.findById(postId)
+                .orElseThrow(() -> new ResourceNotFoundException("Post not found with id: " + postId));
     }
 
     public Optional<Post> updatePost(Integer postId, PostRequest postRequest) {
-        return postRepository.findById(postId)
-                .map(post -> {
-                    post.setTitle(postRequest.getTitle());
-                    post.setContents(postRequest.getContents());
-                    post.setTag(postRequest.getTag());
-                    return postRepository.save(post);
-                });
+        Post post = postRepository.findById(postId)
+                .orElseThrow(() -> new ResourceNotFoundException("Post not found with id: " + postId));
+
+        post.setTitle(postRequest.getTitle());
+        post.setContents(postRequest.getContents());
+        post.setTag(postRequest.getTag());
+
+        return Optional.of(postRepository.save(post));
     }
 
     public void deletePost(Integer postId) {
-        postRepository.findById(postId)
-                .ifPresent(postRepository::delete);
+        Post post = postRepository.findById(postId)
+                .orElseThrow(() -> new ResourceNotFoundException("Post not found with id: " + postId));
+
+        postRepository.delete(post);
     }
 }