♻️ refactor: 사용자 인증 정보를 반환하는 util 메서드 추가

Author: jiwon1217

backend/src/main/java/io/f1/backend/global/util/SecurityUtils.java

@@ -2,21 +2,38 @@
 
 import io.f1.backend.domain.user.dto.UserPrincipal;
 import io.f1.backend.domain.user.entity.User;
-
+import java.util.Collections;
 import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
+import org.springframework.security.core.Authentication;
 import org.springframework.security.core.context.SecurityContextHolder;
 
-import java.util.Collections;
-
 public class SecurityUtils {
 
-    private SecurityUtils() {}
+    private SecurityUtils() {
+    }
 
     public static void setAuthentication(User user) {
         UserPrincipal userPrincipal = new UserPrincipal(user, Collections.emptyMap());
         UsernamePasswordAuthenticationToken authentication =
-                new UsernamePasswordAuthenticationToken(
-                        userPrincipal, null, userPrincipal.getAuthorities());
+            new UsernamePasswordAuthenticationToken(
+                userPrincipal, null, userPrincipal.getAuthorities());
         SecurityContextHolder.getContext().setAuthentication(authentication);
     }
+
+    public static UserPrincipal getCurrentUserPrincipal() {
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        if (authentication != null
+            && authentication.getPrincipal() instanceof UserPrincipal userPrincipal) {
+            return userPrincipal;
+        }
+        throw new RuntimeException("E401001: 로그인이 필요합니다.");
+    }
+
+    public static Long getCurrentUserId() {
+        return getCurrentUserPrincipal().getUserId();
+    }
+
+    public static String getCurrentUserNickname() {
+        return getCurrentUserPrincipal().getUserNickname();
+    }
 }