[BE-Feat] 구글 토큰 관리 기능 구현

backend/src/main/java/endolphin/backend/domain/auth/AuthController.java

@@ -0,0 +1,33 @@
+package endolphin.backend.domain.auth;
+
+import endolphin.backend.domain.auth.dto.OAuthResponse;
+import endolphin.backend.domain.auth.dto.UrlResponse;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+@Tag(name = "Auth", description = "인증 관리 API")
+@RestController
+@RequiredArgsConstructor
+public class AuthController {
+
+    private final AuthService authService;
+
+    @Operation(summary = "구글 로그인 URL", description = "구글 로그인 URL을 반환합니다.")
+    @GetMapping("/api/v1/google")
+    public ResponseEntity<UrlResponse> loginUrl() {
+        UrlResponse response = authService.getGoogleLoginUrl();
+        return ResponseEntity.ok(response);
+    }
+
+    @Operation(summary = "구글 로그인 콜백", description = "사용자가 Google 계정으로 로그인하여 JWT 토큰을 발급받습니다.")
+    @GetMapping("/oauth2/callback")
+    public ResponseEntity<OAuthResponse> oauthCallback(@RequestParam("code") String code) {
+        OAuthResponse response = authService.oauth2Callback(code);
+        return ResponseEntity.ok(response);
+    }
+}

backend/src/main/java/endolphin/backend/domain/auth/AuthService.java

@@ -0,0 +1,58 @@
+package endolphin.backend.domain.auth;
+
+import endolphin.backend.domain.user.UserService;
+import endolphin.backend.global.error.exception.ErrorCode;
+import endolphin.backend.global.error.exception.OAuthException;
+import endolphin.backend.global.google.dto.GoogleTokens;
+import endolphin.backend.global.google.dto.GoogleUserInfo;
+import endolphin.backend.domain.auth.dto.OAuthResponse;
+import endolphin.backend.domain.auth.dto.UrlResponse;
+import endolphin.backend.domain.user.entity.User;
+import endolphin.backend.global.config.GoogleOAuthProperties;
+import endolphin.backend.global.google.GoogleOAuthService;
+import endolphin.backend.global.security.JwtProvider;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@RequiredArgsConstructor
+public class AuthService {
+
+    private final GoogleOAuthProperties googleOAuthProperties;
+    private final GoogleOAuthService googleOAuthService;
+    private final UserService userService;
+    private final JwtProvider jwtProvider;
+
+    public UrlResponse getGoogleLoginUrl() {
+        return new UrlResponse(String.format(
+            "%s?client_id=%s&redirect_uri=%s&response_type=code&scope=%s&access_type=offline&prompt=consent",
+            googleOAuthProperties.authUrl(), googleOAuthProperties.clientId(),
+            googleOAuthProperties.redirectUri(), googleOAuthProperties.scope()));
+    }
+
+    @Transactional
+    public OAuthResponse oauth2Callback(String code) {
+        if (code == null || code.isBlank()) {
+            throw new OAuthException(ErrorCode.INVALID_OAUTH_CODE);
+        }
+        GoogleTokens tokenResponse = googleOAuthService.getGoogleTokens(code);
+        GoogleUserInfo userInfo = googleOAuthService.getUserInfo(tokenResponse.accessToken());
+        validateUserInfo(userInfo);
+        User user = userService.upsertUser(userInfo, tokenResponse);
+        String accessToken = jwtProvider.createToken(user.getId(), user.getEmail());
+        return new OAuthResponse(accessToken);
+    }
+
+    private void validateUserInfo(GoogleUserInfo userInfo) {
+        if (userInfo == null) {
+            throw new OAuthException(ErrorCode.INVALID_OAUTH_USER_INFO);
+        }
+        if (userInfo.email() == null || userInfo.email().isBlank()) {
+            throw new OAuthException(ErrorCode.INVALID_OAUTH_USER_INFO);
+        }
+        if (userInfo.picture() == null || userInfo.picture().isBlank()) {
+            throw new OAuthException(ErrorCode.INVALID_OAUTH_USER_INFO);
+        }
+    }
+}

backend/src/main/java/endolphin/backend/domain/user/dto/OAuthResponse.java → backend/src/main/java/endolphin/backend/domain/auth/dto/OAuthResponse.java

@@ -1,4 +1,4 @@
-package endolphin.backend.domain.user.dto;
+package endolphin.backend.domain.auth.dto;
 
 public record OAuthResponse(String accessToken) {
 

backend/src/main/java/endolphin/backend/domain/user/dto/UrlResponse.java → backend/src/main/java/endolphin/backend/domain/auth/dto/UrlResponse.java

@@ -1,4 +1,4 @@
-package endolphin.backend.domain.user.dto;
+package endolphin.backend.domain.auth.dto;
 
 public record UrlResponse(String url) {
 

backend/src/main/java/endolphin/backend/domain/user/UserController.java

@@ -1,13 +1,7 @@
 package endolphin.backend.domain.user;
 
-import endolphin.backend.domain.user.dto.OAuthResponse;
-import endolphin.backend.domain.user.dto.UrlResponse;
-import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
 import lombok.RequiredArgsConstructor;
-import org.springframework.http.ResponseEntity;
-import org.springframework.web.bind.annotation.GetMapping;
-import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 
 @Tag(name = "User", description = "사용자 관리 API")
@@ -17,17 +11,4 @@ public class UserController {
 
     private final UserService userService;
 
-    @Operation(summary = "구글 로그인 URL", description = "구글 로그인 URL을 반환합니다.")
-    @GetMapping("/api/v1/google")
-    public ResponseEntity<UrlResponse> loginUrl() {
-        UrlResponse response = userService.getGoogleLoginUrl();
-        return ResponseEntity.ok(response);
-    }
-
-    @Operation(summary = "구글 로그인 콜백", description = "사용자가 Google 계정으로 로그인하여 JWT 토큰을 발급받습니다.")
-    @GetMapping("/oauth2/callback")
-    public ResponseEntity<OAuthResponse> oauthCallback(@RequestParam("code") String code) {
-        OAuthResponse response = userService.oauth2Callback(code);
-        return ResponseEntity.ok(response);
-    }
 }

backend/src/main/java/endolphin/backend/domain/user/UserService.java

@@ -1,112 +1,48 @@
 package endolphin.backend.domain.user;
 
-import endolphin.backend.domain.user.dto.GoogleUserInfo;
-import endolphin.backend.domain.user.dto.GoogleTokens;
-import endolphin.backend.domain.user.dto.OAuthResponse;
-import endolphin.backend.domain.user.dto.UrlResponse;
+import endolphin.backend.global.google.dto.GoogleUserInfo;
+import endolphin.backend.global.google.dto.GoogleTokens;
 import endolphin.backend.domain.user.entity.User;
-import endolphin.backend.global.config.GoogleOAuthProperties;
 import endolphin.backend.global.error.exception.ApiException;
 import endolphin.backend.global.error.exception.ErrorCode;
-import endolphin.backend.global.security.JwtProvider;
 import endolphin.backend.global.security.UserContext;
 import endolphin.backend.global.security.UserInfo;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
-import org.springframework.http.HttpEntity;
-import org.springframework.http.HttpHeaders;
-import org.springframework.http.HttpMethod;
-import org.springframework.http.MediaType;
-import org.springframework.http.ResponseEntity;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
-import org.springframework.util.LinkedMultiValueMap;
-import org.springframework.util.MultiValueMap;
-import org.springframework.web.client.RestTemplate;
 
 @Service
 @RequiredArgsConstructor
 @Transactional
 @Slf4j
 public class UserService {
-
-    private final GoogleOAuthProperties googleOAuthProperties;
     private final UserRepository userRepository;
-    private final JwtProvider jwtProvider;
-    private final RestTemplate restTemplate;
-
-    public UrlResponse getGoogleLoginUrl() {
-        return new UrlResponse(String.format(
-            "%s?client_id=%s&redirect_uri=%s&response_type=code&scope=%s&access_type=offline",
-            googleOAuthProperties.authUrl(), googleOAuthProperties.clientId(),
-            googleOAuthProperties.redirectUri(), googleOAuthProperties.scope()));
-    }
-
-    public OAuthResponse oauth2Callback(String code) {
-        GoogleTokens tokenResponse = getAccessToken(code);
-        GoogleUserInfo userInfo = getUserInfo(tokenResponse.accessToken());
-        User user = createUser(userInfo, tokenResponse);
-        String accessToken = jwtProvider.createToken(user.getId(), user.getEmail());
-        return new OAuthResponse(accessToken);
-    }
 
+    @Transactional(readOnly = true)
     public User getCurrentUser() {
         UserInfo userInfo = UserContext.get();
         return userRepository.findById(userInfo.userId())
             .orElseThrow(() -> new ApiException(ErrorCode.USER_NOT_FOUND));
     }
 
-    private User createUser(GoogleUserInfo userInfo, GoogleTokens tokenResponse) {
+    public void updateAccessToken(User user, String accessToken) {
+        user.setAccessToken(accessToken);
+        userRepository.save(user);
+    }
+
+    public User upsertUser(GoogleUserInfo userInfo, GoogleTokens tokenResponse) {
         User user = userRepository.findByEmail(userInfo.email())
             .orElseGet(() -> {
                 return User.builder()
                     .email(userInfo.email())
                     .name(userInfo.name())
                     .picture(userInfo.picture())
-                    .accessToken(tokenResponse.accessToken())
-                    .refreshToken(tokenResponse.refreshToken())
                     .build();
             });
+        user.setAccessToken(tokenResponse.accessToken());
+        user.setRefreshToken(tokenResponse.refreshToken());
         userRepository.save(user);
         return user;
     }
-
-    private GoogleTokens getAccessToken(String code) {
-        HttpHeaders headers = new HttpHeaders();
-        headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
-
-        HttpEntity<MultiValueMap<String, String>> request = getHttpEntity(
-            code, headers);
-        ResponseEntity<GoogleTokens> response = restTemplate.postForEntity(
-            googleOAuthProperties.tokenUrl(), request,
-            GoogleTokens.class);
-
-        return response.getBody();
-    }
-
-    private HttpEntity<MultiValueMap<String, String>> getHttpEntity(String code,
-        HttpHeaders headers) {
-        MultiValueMap<String, String> params = new LinkedMultiValueMap<>();
-        params.add("client_id", googleOAuthProperties.clientId());
-        params.add("client_secret", googleOAuthProperties.clientSecret());
-        params.add("redirect_uri", googleOAuthProperties.redirectUri());
-        params.add("code", code);
-        params.add("grant_type", "authorization_code");
-        params.add("access_type", "offline");
-
-        HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(params, headers);
-        return request;
-    }
-
-    private GoogleUserInfo getUserInfo(String accessToken) {
-        HttpHeaders headers = new HttpHeaders();
-        headers.setBearerAuth(accessToken);
-
-        HttpEntity<String> entity = new HttpEntity<>(headers);
-
-        ResponseEntity<GoogleUserInfo> result = restTemplate.exchange(googleOAuthProperties.userInfoUrl(),
-            HttpMethod.GET, entity, GoogleUserInfo.class);
-
-        return result.getBody();
-    }
 }

backend/src/main/java/endolphin/backend/domain/user/entity/User.java

@@ -28,8 +28,10 @@ public class User extends BaseTimeEntity {
     private String email;
     @Column(nullable = false)
     private String picture;
+    @Setter
     @Column(name = "access_token")
     private String accessToken;
+    @Setter
     @Column(name = "refresh_token")
     private String refreshToken;
 
@@ -42,4 +44,5 @@ public User(String name, String email, String picture, String accessToken,
         this.accessToken = accessToken;
         this.refreshToken = refreshToken;
     }
+
 }

backend/src/main/java/endolphin/backend/global/config/RestTemplateConfig.java → backend/src/main/java/endolphin/backend/global/config/RestClientConfig.java

@@ -3,20 +3,16 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.client.SimpleClientHttpRequestFactory;
-import org.springframework.web.client.RestTemplate;
+import org.springframework.web.client.RestClient;
 
 @Configuration
-public class RestTemplateConfig {
+public class RestClientConfig {
 
     @Bean
-    public RestTemplate restTemplate() {
-        RestTemplate restTemplate = new RestTemplate();
+    public RestClient restClient() {
         SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();
         requestFactory.setConnectTimeout(5000);
         requestFactory.setReadTimeout(5000);
-
-        restTemplate.setRequestFactory(requestFactory);
-
-        return restTemplate;
+        return RestClient.builder().requestFactory(requestFactory).build();
     }
 }

backend/src/main/java/endolphin/backend/global/error/GlobalExceptionHandler.java

@@ -2,6 +2,7 @@
 
 import endolphin.backend.global.error.exception.ApiException;
 import endolphin.backend.global.error.exception.ErrorCode;
+import endolphin.backend.global.error.exception.OAuthException;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
@@ -20,6 +21,14 @@ public ResponseEntity<ErrorResponse> handleApiException(ApiException e) {
         return ResponseEntity.status(e.getErrorCode().getHttpStatus()).body(response);
     }
 
+    @ExceptionHandler(OAuthException.class)
+    public ResponseEntity<ErrorResponse> handleOAuthException(OAuthException e) {
+        log.error("[OAuth exception] Error code: {}, Message: {}",
+            e.getErrorCode(), e.getMessage(), e);
+        ErrorResponse response = ErrorResponse.of(e.getErrorCode());
+        return ResponseEntity.status(e.getErrorCode().getHttpStatus()).body(response);
+    }
+
     @ExceptionHandler(Exception.class)
     public ResponseEntity<ErrorResponse> handleUnexpectedException(Exception e) {
         log.error("[Unexpected exception] ", e);

backend/src/main/java/endolphin/backend/global/error/exception/ErrorCode.java

@@ -16,8 +16,14 @@ public enum ErrorCode {
     DISCUSSION_NOT_FOUND(HttpStatus.NOT_FOUND, "D001", "Discussion not found"),
 
     //SharedEvent
-    SHARED_EVENT_NOT_FOUND(HttpStatus.NOT_FOUND, "S001", "Shared Event not found")
+    SHARED_EVENT_NOT_FOUND(HttpStatus.NOT_FOUND, "S001", "Shared Event not found"),
 
+    // OAuth
+    OAUTH_UNAUTHORIZED_ERROR(HttpStatus.UNAUTHORIZED, "O001", "OAuth Unauthorized Error"),
+    OAUTH_BAD_REQUEST_ERROR(HttpStatus.BAD_REQUEST, "O002", "OAuth Bad Request Error"),
+    OAUTH_FORBIDDEN_ERROR(HttpStatus.FORBIDDEN, "O003", "OAuth Forbidden Error"),
+    INVALID_OAUTH_CODE(HttpStatus.UNAUTHORIZED, "O004", "Invalid OAuth Code"),
+    INVALID_OAUTH_USER_INFO(HttpStatus.UNAUTHORIZED, "O005", "Invalid OAuth User Info"),
     ;
     private final HttpStatus httpStatus;
     private final String code;

backend/src/main/java/endolphin/backend/global/error/exception/OAuthException.java

@@ -0,0 +1,25 @@
+package endolphin.backend.global.error.exception;
+
+import lombok.Getter;
+import org.springframework.http.HttpStatus;
+
+@Getter
+public class OAuthException extends RuntimeException {
+
+    private final ErrorCode errorCode;
+
+    public OAuthException(HttpStatus status, String message) {
+        super(message);
+        switch (status) {
+            case UNAUTHORIZED -> errorCode = ErrorCode.OAUTH_UNAUTHORIZED_ERROR;
+            case FORBIDDEN -> errorCode = ErrorCode.OAUTH_FORBIDDEN_ERROR;
+            case BAD_REQUEST -> errorCode = ErrorCode.OAUTH_BAD_REQUEST_ERROR;
+            default -> errorCode = ErrorCode.INTERNAL_ERROR;
+        }
+    }
+
+    public OAuthException(ErrorCode errorCode) {
+        super(errorCode.getMessage());
+        this.errorCode = errorCode;
+    }
+}