feat : 리프레시 토큰 핵심 서비스 작성

Author: seungwookc97

src/main/java/com/back/domain/auth/refreshToken/repository/RefreshTokenRepository.java

@@ -4,6 +4,12 @@
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.stereotype.Repository;
 
+import java.util.Optional;
+
 @Repository
 public interface RefreshTokenRepository extends CrudRepository<RefreshToken, String> {
+
+    Optional<RefreshToken> findByToken(String token);
+
+    void deleteByToken(String token);
 }

src/main/java/com/back/domain/auth/refreshToken/service/RefreshTokenService.java

@@ -0,0 +1,62 @@
+package com.back.domain.auth.refreshToken.service;
+
+import com.back.domain.auth.refreshToken.entity.RefreshToken;
+import com.back.domain.auth.refreshToken.repository.RefreshTokenRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Service;
+
+import java.security.SecureRandom;
+import java.util.Base64;
+import java.util.Optional;
+
+@Service
+@RequiredArgsConstructor
+public class RefreshTokenService {
+
+    private final RefreshTokenRepository refreshTokenRepository;
+    private final SecureRandom secureRandom = new SecureRandom();
+
+    @Value("${custom.refreshToken.expirationSeconds}")
+    private long refreshTokenExpiration;
+
+    // 기존 리프레시 토큰 삭제하고 생성
+    public String generateRefreshToken(Long userId, String email) {
+        String token = generateSecureToken();
+        RefreshToken refreshToken = RefreshToken.create(token, userId, email, refreshTokenExpiration);
+        refreshTokenRepository.save(refreshToken);
+
+        return token;
+    }
+
+    //검증
+    public boolean validateToken(String token) {
+        return refreshTokenRepository.findByToken(token).isPresent();
+    }
+
+    //기존 토큰 지우고 발급(회전)
+    public String rotateToken(String oldToken) {
+        Optional<RefreshToken> oldRefreshToken = refreshTokenRepository.findByToken(oldToken);
+
+        if (oldRefreshToken.isEmpty()) {
+            throw new IllegalArgumentException("Invalid refresh token");
+        }
+
+        RefreshToken tokenData = oldRefreshToken.get();
+        revokeToken(oldToken);
+
+        return generateRefreshToken(tokenData.getUserId(), tokenData.getEmail());
+    }
+
+    //삭제
+    public void revokeToken(String token) {
+        refreshTokenRepository.deleteByToken(token);
+    }
+
+    //문자열 난수 조합
+    private String generateSecureToken() {
+        byte[] randomBytes = new byte[32];
+        secureRandom.nextBytes(randomBytes);
+        return Base64.getEncoder().withoutPadding().encodeToString(randomBytes);
+    }
+}

src/main/java/com/back/global/jwt/JwtUtil.java

@@ -20,6 +20,7 @@ public class JwtUtil {
     private final SecretKey secretKey;
     private final long accessTokenExpiration;
     private static final String ACCESS_TOKEN_COOKIE_NAME = "accessToken";
+    private static final String REFRESH_TOKEN_COOKIE_NAME = "refreshToken";
 
     public JwtUtil(@Value("${custom.jwt.secretKey}") String secretKey,
                    @Value("${custom.accessToken.expirationSeconds}") long accessTokenExpiration) {