refactor: 토큰 관련 로직을 별도의 클래스로 추상화

backend/src/main/java/harustudy/backend/auth/util/AesTokenProvider.java

@@ -1,30 +1,28 @@
 package harustudy.backend.auth.util;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import harustudy.backend.auth.exception.InvalidAccessTokenException;
 import java.nio.charset.StandardCharsets;
 import java.security.GeneralSecurityException;
-import java.text.ParseException;
-import java.text.SimpleDateFormat;
 import java.util.Base64;
-import java.util.Date;
 import javax.crypto.Cipher;
 import javax.crypto.spec.IvParameterSpec;
 import javax.crypto.spec.SecretKeySpec;
+import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Component;
 
+@RequiredArgsConstructor
 @Component
 public class AesTokenProvider {
 
     private static final String alg = "AES/CBC/PKCS5Padding";
     private static final String iv = "0123456789abcdef"; // 16byte
-    private static final SimpleDateFormat DATE_FORMAT = new SimpleDateFormat("MMddHH:mm:ssyyyy");
+
+    private final ObjectMapper objectMapper;
 
     public String createAccessToken(Long subject, Long accessTokenExpireLength, String secretKey) {
-        Date now = new Date();
-        Date expireAt = new Date(now.getTime() + accessTokenExpireLength);
-        String formatted = DATE_FORMAT.format(expireAt);
-        String text = subject + " " + formatted;
-        return encrypt(text, secretKey);
+        String token = AccessTokenUtils.issue(objectMapper, subject, accessTokenExpireLength);
+        return encrypt(token, secretKey);
     }
 
     private String encrypt(String text, String secretKey) {
@@ -42,50 +40,21 @@ private String encrypt(String text, String secretKey) {
     }
 
     public Long parseSubject(String accessToken, String secretKey) {
-        String[] splitted = decrypt(accessToken, secretKey);
-        validateLength(splitted);
-        validateExpiration(splitted);
-        return parseSubject(splitted);
+        byte[] decrypted = decrypt(accessToken, secretKey);
+        return AccessTokenUtils.parseSubject(objectMapper, decrypted);
     }
 
-    private String[] decrypt(String accessToken, String secretKey) {
+    private byte[] decrypt(String accessToken, String secretKey) {
         try {
             Cipher cipher = Cipher.getInstance(alg);
             SecretKeySpec keySpec = new SecretKeySpec(secretKey.getBytes(), "AES");
             IvParameterSpec ivParamSpec = new IvParameterSpec(iv.getBytes());
             cipher.init(Cipher.DECRYPT_MODE, keySpec, ivParamSpec);
 
             byte[] decodedBytes = Base64.getDecoder().decode(accessToken);
-            byte[] decrypted = cipher.doFinal(decodedBytes);
-            String string = new String(decrypted, StandardCharsets.UTF_8);
-            return string.split(" ");
+            return cipher.doFinal(decodedBytes);
         } catch (GeneralSecurityException | IllegalArgumentException e) {
             throw new InvalidAccessTokenException();
         }
     }
-
-    private void validateLength(String[] splitted) {
-        if (splitted.length != 2) {
-            throw new InvalidAccessTokenException();
-        }
-    }
-
-    private void validateExpiration(String[] splitted) {
-        Date expireAt = parseExpirationDate(splitted);
-        if (expireAt.before(new Date())) {
-            throw new InvalidAccessTokenException();
-        }
-    }
-
-    private Date parseExpirationDate(String[] splitted) {
-        try {
-            return DATE_FORMAT.parse(splitted[1]);
-        } catch (ParseException e) {
-            throw new InvalidAccessTokenException();
-        }
-    }
-
-    private Long parseSubject(String[] splitted) {
-        return Long.parseLong(splitted[0]);
-    }
 }