Feat: FCM Service 기능 구현

backend/src/main/java/com/worlabel/global/config/FCMConfig.java

@@ -40,12 +40,10 @@ public class FCMConfig {
             FirebaseApp firebaseApp = FirebaseApp.getApps().isEmpty() ?
                     FirebaseApp.initializeApp(options) :
                     FirebaseApp.getInstance();
-            log.debug("firebase 불러오기 성공");
             // 설정된 FirebaseApp 연결된 FirebaseMessaging 인스턴스를 반환
             return FirebaseMessaging.getInstance(firebaseApp);
         } catch (IOException e) {
             throw new CustomException(ErrorCode.SERVER_ERROR, "Firebase Key 불러오기 실패 ");
         }
     }
-
 }

backend/src/main/java/com/worlabel/global/service/FCMService.java

@@ -0,0 +1,29 @@
+package com.worlabel.global.service;
+
+import com.google.firebase.messaging.FirebaseMessaging;
+import com.google.firebase.messaging.Message;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Service;
+
+@Slf4j
+@Service
+@RequiredArgsConstructor
+public class FCMService {
+
+    private final FirebaseMessaging firebaseMessaging;
+
+    private void sendNotification(String targetToken, String title, String body){
+        Message message = Message.builder()
+                .setToken(targetToken)
+                .putData("title",title)
+                .putData("body",body)
+                .build();
+        try {
+            log.debug("FCM 알림 전송 {}", message);
+            firebaseMessaging.sendAsync(message);
+        } catch (Exception e) {
+            log.error("FCM 전송 오류 ", e);
+        }
+    }
+}