feat: 토큰 재발급 기능 구현

src/main/java/com/linku/backend/domain/user/User.java

@@ -3,6 +3,7 @@
 import com.linku.backend.domain.common.BaseEntity;
 import com.linku.backend.domain.oauth.dto.GoogleUserInfo;
 import com.linku.backend.global.auth.AuthRole;
+import com.linku.backend.global.exception.LinkuException;
 import jakarta.persistence.*;
 import lombok.AllArgsConstructor;
 import lombok.Getter;
@@ -12,6 +13,8 @@
 
 import java.time.LocalDateTime;
 
+import static com.linku.backend.global.response.ResponseCode.GOOGLE_MAIL_INVALID;
+
 @Entity
 @Table(name = "users")
 @SuperBuilder
@@ -35,6 +38,9 @@ public class User extends BaseEntity {
     @Column(nullable = false, unique = true, length = 30)
     private String providerId;
 
+    @Column(length = 1024)
+    private String picture;
+
     @Column(length = 20)
     @Enumerated(EnumType.STRING)
     private AuthRole authRole;
@@ -45,19 +51,34 @@ public static User guest(GoogleUserInfo userInfo) {
         return new User(
                 userInfo.sub(),
                 userInfo.email(),
-                userInfo.name()
+                userInfo.name(),
+                userInfo.picture()
         );
     }
 
-    private User(String providerId, String gMail, String name) {
+    private User(String providerId, String gMail, String name, String picture) {
         this.providerId = providerId;
         this.gMail = gMail;
         this.name = name;
+        this.picture = picture;
         this.authRole = AuthRole.ROLE_GUEST;
     }
 
     public void updateInfo(String kuMail) {
         this.kuMail = kuMail;
         this.authRole = AuthRole.ROLE_MEMBER;
     }
+
+    public String getGoogleId() {
+        if (gMail == null || gMail.isBlank()) {
+            return null;
+        }
+
+        int atIndex = gMail.indexOf('@');
+        if (atIndex <= 0) {
+            throw LinkuException.of(GOOGLE_MAIL_INVALID);
+        }
+
+        return gMail.substring(0, atIndex);
+    }
 }

src/main/java/com/linku/backend/global/auth/controller/AuthController.java

@@ -4,7 +4,9 @@
 import com.linku.backend.domain.user.service.UserService;
 import com.linku.backend.global.auth.dto.KUMailRequest;
 import com.linku.backend.global.auth.dto.KUMailVerifyRequest;
+import com.linku.backend.global.auth.dto.TokenReissueRequest;
 import com.linku.backend.global.auth.dto.UserInfoResponse;
+import com.linku.backend.global.auth.service.AuthService;
 import com.linku.backend.global.auth.service.MailService;
 import com.linku.backend.global.jwt.JwtTokenService;
 import com.linku.backend.global.response.BaseResponse;
@@ -22,6 +24,7 @@ public class AuthController {
 
     private final MailService mailService;
     private final UserService userService;
+    private final AuthService authService;
 
     @PostMapping("/send-code")
     public BaseResponse<Void> sendAuthCode(@Validated @RequestBody KUMailRequest request) {
@@ -39,4 +42,10 @@ public BaseResponse<UserInfoResponse> verifyAuthCode(@Validated @RequestBody KUM
         UserInfoResponse response = userService.updateInfo(request.kuMail(), guestToken);
         return BaseResponse.of(ResponseCode.SUCCESS, response);
     }
+
+    @PostMapping("/token")
+    public BaseResponse<UserInfoResponse> reissueToken(@RequestBody TokenReissueRequest request) {
+        UserInfoResponse response = authService.reissueToken(request.refreshToken());
+        return BaseResponse.of(ResponseCode.SUCCESS, response);
+    }
 }

src/main/java/com/linku/backend/global/auth/dto/TokenReissueRequest.java

@@ -0,0 +1,4 @@
+package com.linku.backend.global.auth.dto;
+
+public record TokenReissueRequest(String refreshToken) {
+}

src/main/java/com/linku/backend/global/auth/dto/UserInfoResponse.java

@@ -5,15 +5,17 @@
 public record UserInfoResponse(
         String accessToken,
         String refreshToken,
-        Long userId,
+        String googleId,
+        String profileImage,
         String name,
         String kuMail
 ) {
     public static UserInfoResponse from(User user, AuthTokenResponse authTokenResponse) {
         return new UserInfoResponse(
                 authTokenResponse.accessToken(),
                 authTokenResponse.refreshToken(),
-                user.getUserId(),
+                user.getGoogleId(),     // 구글 이메일이 등록되어 있지 않으면 null이 반환됨
+                user.getPicture(),
                 user.getName(),
                 user.getKuMail()
         );

src/main/java/com/linku/backend/global/auth/service/AuthService.java

@@ -0,0 +1,30 @@
+package com.linku.backend.global.auth.service;
+
+import com.linku.backend.domain.user.User;
+import com.linku.backend.domain.user.service.UserService;
+import com.linku.backend.global.auth.AuthUser;
+import com.linku.backend.global.auth.dto.AuthTokenResponse;
+import com.linku.backend.global.auth.dto.UserInfoResponse;
+import com.linku.backend.global.jwt.JwtTokenService;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Slf4j
+@RequiredArgsConstructor
+@Transactional(readOnly = true)
+@Service
+public class AuthService {
+
+    private final JwtTokenService jwtTokenService;
+    private final UserService userService;
+
+    @Transactional
+    public UserInfoResponse reissueToken(String refreshToken) {
+        AuthUser authUser = (AuthUser) jwtTokenService.validateToken(refreshToken, JwtTokenService.REFRESH);
+        User user = userService.getUserById(authUser.getId());
+        AuthTokenResponse authToken = jwtTokenService.generateAuthToken(user);
+        return UserInfoResponse.from(user, authToken);
+    }
+}

src/main/java/com/linku/backend/global/jwt/JwtTokenService.java

@@ -72,7 +72,11 @@ public String generateGuestToken(Long userId) {
 
     private String generateToken(Claims claims, long expiration, String type) {
         claims.put("type", type);
-        return Jwts.builder().setClaims(claims).setIssuedAt(new Date(System.currentTimeMillis())).setExpiration(new Date(System.currentTimeMillis() + expiration)).signWith(SignatureAlgorithm.HS256, secretKey).compact();
+        return Jwts.builder().setClaims(claims)
+                .setIssuedAt(new Date(System.currentTimeMillis()))
+                .setExpiration(new Date(System.currentTimeMillis() + expiration))
+                .signWith(SignatureAlgorithm.HS256, secretKey)
+                .compact();
     }
 
     // 토큰 검증 이후에 사용

src/main/java/com/linku/backend/global/response/ResponseCode.java

@@ -56,7 +56,8 @@ public enum ResponseCode {
     KUMAIL_ALREADY(false, 5014, "이미 존재하는 건국대학교 이메일입니다."),
     MAIL_SEND_FAIL(false, 5015, "메일 전송 중 오류가 발생했습니다."),
     AUTH_CODE_INVALID(false, 5016, "이메일 인증에 실패했습니다. 인증 코드가 올바르지 않습니다."),
-
+    GOOGLE_MAIL_INVALID(false, 5017, "구글 이메일 형식이 올바르지 않습니다."),
+
     // 6000대 : Crawling 관련 요청 성공/실패
     CRAWLING_FAILED(false, 6000, "크롤링을 실패하였습니다."),
     CRAWLING_PARSING_FAILED(false, 6001, "크롤링 파싱을 실패하였습니다."),