Feat: 카카오 소셜 로그인 기능 구현

src/main/java/org/example/siljeun/domain/auth/controller/AuthController.java

@@ -1,6 +1,7 @@
 package org.example.siljeun.domain.auth.controller;
 
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 import org.example.siljeun.domain.auth.dto.request.LoginRequest;
 import org.example.siljeun.domain.auth.dto.request.SignUpRequest;
 import org.example.siljeun.domain.auth.dto.response.LoginResponse;
@@ -17,6 +18,7 @@
 @RestController
 @RequestMapping("/auth")
 @RequiredArgsConstructor
+@Slf4j
 public class AuthController {
 
   private final AuthService authService;
@@ -33,6 +35,7 @@ public ResponseEntity<SignUpResponse> signUp(@RequestBody SignUpRequest request)
   @PostMapping("/login")
   public ResponseDto<LoginResponse> login(@RequestBody LoginRequest request) {
     try {
+      log.debug("----- 로그인 메서드 실행 -----");
       LoginResponse response = authService.login(request.username(), request.password());
       return ResponseDto.success("로그인 성공", response);
     } catch (Exception e) {

src/main/java/org/example/siljeun/domain/auth/service/AuthService.java

@@ -24,8 +24,8 @@ public SignUpResponse signUp(SignUpRequest request) {
     String password = passwordEncoder.encode(request.password());
 
     // 회원 생성 및 저장
-    User user = new User(request.email(), request.username(), password, request.nickname(),
-        request.role(), request.provider());
+    User user = new User(request.email(), request.username(), password, request.name(),
+        request.nickname(), request.role(), request.provider());
     User savedUser = userRepository.save(user);
 
     return new SignUpResponse(savedUser.getId(), savedUser.getEmail(), savedUser.getUsername());

src/main/java/org/example/siljeun/domain/oauth/client/KakaoApiClient.java → src/main/java/org/example/siljeun/domain/oauth/client/KakaoOAuthClient.java

@@ -1,73 +1,71 @@
 package org.example.siljeun.domain.oauth.client;
 
-import java.util.Map;
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.example.siljeun.domain.oauth.dto.KakaoAccessToken;
 import org.example.siljeun.domain.oauth.dto.KakaoUserInfo;
-import org.example.siljeun.global.config.KakaoOAuthProperties;
-import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
-import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
-import org.springframework.http.ResponseEntity;
 import org.springframework.stereotype.Component;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.client.RestTemplate;
 
 @Component
 @RequiredArgsConstructor
-public class KakaoApiClient {
+@Slf4j
+public class KakaoOAuthClient {
 
   private final RestTemplate restTemplate;
-  private final KakaoOAuthProperties properties;
 
+  // 현재 카카오 API 서버에서 인가 코드를 제공한 상태이다
+  // 서비스 서버가 인가 코드를 이용해 카카오 API 서버로 액세스 토큰을 요청한다
   public String getAccessToken(String code) {
     HttpHeaders headers = new HttpHeaders();
     headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
 
     MultiValueMap<String, String> params = new LinkedMultiValueMap<>();
+    // 아래 4가지 값은 필수
     params.add("grant_type", "authorization_code");
-    params.add("client_id", "eaee0e144aeb9afef54d5c449448baea");
-    params.add("redirect_uri", "http://localhost:8080/oauth/kakao/callback");
-    params.add("code", code);
+    params.add("client_id", "eaee0e144aeb9afef54d5c449448baea"); // 카카오 REST API 키
+    params.add("redirect_uri", "http://localhost:8080/oauth/kakao/callback"); // 여기서 문제 발생?
+    params.add("code", code); // 인가 코드
 
     HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(params, headers);
 
-    ResponseEntity<Map<String, Object>> response = restTemplate.exchange(
+    // 명시한 URL로 (인가 코드를 담은) POST 요청을 보내면 카카오 API 서버에서 액세스 토큰을 응답한다
+    KakaoAccessToken response = restTemplate.postForEntity(
         "https://kauth.kakao.com/oauth/token",
-        HttpMethod.POST,
         request,
-        new ParameterizedTypeReference<>() {
-        }
-    );
+        KakaoAccessToken.class
+    ).getBody();
 
-    if (response.getStatusCode() != HttpStatus.OK || response.getBody() == null) {
-      throw new RuntimeException("카카오 Access Token 요청 실패");
-    }
+    log.debug("----- 액세스 토큰: {} -----", response.accessToken());
 
-    return response.getBody().get("access_token").toString();
+    return response.accessToken();
   }
 
+  // 서비스 서버가 카카오 인증 서버에 저장된 회원 정보를 요청한다
   public KakaoUserInfo getUserInfo(String accessToken) {
-    HttpHeaders headers = new HttpHeaders();
+    // HTTP 헤더 설정
+    final HttpHeaders headers = new HttpHeaders();
     headers.setBearerAuth(accessToken);
+    headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
 
-    HttpEntity<Void> request = new HttpEntity<>(headers);
+    // 설정한 HTTP 헤더를 이용해 요청 생성
+    final HttpEntity<Void> request = new HttpEntity<>(headers);
 
-    ResponseEntity<KakaoUserInfo> response = restTemplate.exchange(
+    // GET 메서드로 회원 정보를 요청한 후 KakaoUserInfo 객체에 담음
+    final KakaoUserInfo response = restTemplate.exchange(
         "https://kapi.kakao.com/v2/user/me",
         HttpMethod.GET,
         request,
         KakaoUserInfo.class
-    );
-
-    if (response.getStatusCode() != HttpStatus.OK || response.getBody() == null) {
-      throw new RuntimeException("카카오 사용자 정보 요청 실패");
-    }
+    ).getBody();
 
-    return response.getBody();
+    return response;
   }
 
-}
+}

src/main/java/org/example/siljeun/domain/oauth/controller/OAuthController.java

@@ -1,8 +1,9 @@
 package org.example.siljeun.domain.oauth.controller;
 
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.example.siljeun.domain.auth.dto.response.LoginResponse;
 import org.example.siljeun.domain.oauth.service.KakaoOAuthService;
-import org.example.siljeun.global.dto.ResponseDto;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
@@ -12,14 +13,21 @@
 @RestController
 @RequiredArgsConstructor
 @RequestMapping("/oauth")
+@Slf4j
 public class OAuthController {
 
   private final KakaoOAuthService kakaoOAuthService;
 
+  /*
+     1. 클라이언트가 카카오 로그인을 요청한다
+     2. /oauth/kakao/callback?code={code}로 리다이렉트된다
+     3. 이때 카카오에서 쿼리 스트링으로 인가 코드를 넘겨준다
+     4. 넘어온 인가 코드를 이용해서 카카오 로그인 API를 호출한다
+   */
   @GetMapping("/kakao/callback")
-  public ResponseEntity<?> kakaoCallback(@RequestParam String code) {
-    String jwt = kakaoOAuthService.kakaoLogin(code);
-    return ResponseEntity.ok(jwt);
+  public ResponseEntity<LoginResponse> kakaoCallback(@RequestParam String code) {
+    log.debug("---------- METHOD: kakaoCallback ----------");
+    return ResponseEntity.ok(kakaoOAuthService.kakaoLogin(code));
   }
 
 }

src/main/java/org/example/siljeun/domain/oauth/dto/KakaoAccessToken.java

@@ -0,0 +1,13 @@
+package org.example.siljeun.domain.oauth.dto;
+
+import com.fasterxml.jackson.databind.PropertyNamingStrategies;
+import com.fasterxml.jackson.databind.annotation.JsonNaming;
+
+@JsonNaming(PropertyNamingStrategies.SnakeCaseStrategy.class)
+public record KakaoAccessToken(String tokenType,
+                               String accessToken,
+                               Integer expiresIn,
+                               String refreshToken,
+                               Integer refreshTokenExpiresIn) {
+
+}

src/main/java/org/example/siljeun/domain/oauth/dto/KakaoAccount.java

@@ -0,0 +1,12 @@
+package org.example.siljeun.domain.oauth.dto;
+
+import com.fasterxml.jackson.databind.PropertyNamingStrategies;
+import com.fasterxml.jackson.databind.annotation.JsonNaming;
+
+@JsonNaming(PropertyNamingStrategies.SnakeCaseStrategy.class)
+public record KakaoAccount(
+    KakaoProfile profile, // 프로필 정보(닉네임, 프로필 사진)
+    String email
+) {
+
+}

src/main/java/org/example/siljeun/domain/oauth/dto/KakaoProfile.java

@@ -0,0 +1,12 @@
+package org.example.siljeun.domain.oauth.dto;
+
+import com.fasterxml.jackson.databind.PropertyNamingStrategies;
+import com.fasterxml.jackson.databind.annotation.JsonNaming;
+
+@JsonNaming(PropertyNamingStrategies.SnakeCaseStrategy.class)
+public record KakaoProfile(
+    String nickname,
+    String profileImageUrl
+) {
+
+}

src/main/java/org/example/siljeun/domain/oauth/dto/KakaoUserInfo.java

@@ -1,41 +1,12 @@
 package org.example.siljeun.domain.oauth.dto;
 
-import java.util.Map;
-import lombok.AllArgsConstructor;
-import lombok.Getter;
-
-@Getter
-@AllArgsConstructor
-public class KakaoUserInfo implements OAuth2UserInfo {
-
-  private Map<String, Object> attributes;
-  private Map<String, Object> attributesAccount;
-  private Map<String, Object> attributesProfile;
-
-  public KakaoUserInfo(Map<String, Object> attributes) {
-    this.attributes = attributes;
-    this.attributesAccount = (Map<String, Object>) attributes.get("kakao_account");
-    this.attributesProfile = (Map<String, Object>) attributesAccount.get("profile");
-  }
-
-  @Override
-  public String getProvider() {
-    return "Kakao";
-  }
-
-  @Override
-  public String getProviderId() {
-    return attributes.get("id").toString();
-  }
-
-  @Override
-  public String getEmail() {
-    return attributesAccount.get("email").toString();
-  }
-
-  @Override
-  public String getNickname() {
-    return attributesProfile.get("nickname").toString();
-  }
+import com.fasterxml.jackson.databind.PropertyNamingStrategies;
+import com.fasterxml.jackson.databind.annotation.JsonNaming;
+
+@JsonNaming(PropertyNamingStrategies.SnakeCaseStrategy.class)
+public record KakaoUserInfo(
+    Long id,                  // 회원 번호
+    KakaoAccount kakaoAccount // 카카오 계정 정보
+) {
 
 }

src/main/java/org/example/siljeun/domain/oauth/service/KakaoOAuthService.java

@@ -1,40 +1,73 @@
 package org.example.siljeun.domain.oauth.service;
 
 import lombok.RequiredArgsConstructor;
-import org.example.siljeun.domain.oauth.client.KakaoApiClient;
+import lombok.extern.slf4j.Slf4j;
+import org.example.siljeun.domain.auth.dto.response.LoginResponse;
+import org.example.siljeun.domain.oauth.client.KakaoOAuthClient;
 import org.example.siljeun.domain.oauth.dto.KakaoUserInfo;
 import org.example.siljeun.domain.user.entity.User;
 import org.example.siljeun.domain.user.enums.Provider;
+import org.example.siljeun.domain.user.enums.Role;
 import org.example.siljeun.domain.user.repository.UserRepository;
 import org.example.siljeun.global.security.JwtUtil;
+import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.stereotype.Service;
 
 @Service
 @RequiredArgsConstructor
+@Slf4j
 public class KakaoOAuthService {
 
-  private final KakaoApiClient kakaoApiClient;
+  private final KakaoOAuthClient kakaoOAuthClient;
   private final UserRepository userRepository;
   private final JwtUtil jwtUtil;
+  private final PasswordEncoder passwordEncoder;
 
-  public String kakaoLogin(String code) {
-    // 1. 액세스 토큰 요청
-    String accessToken = kakaoApiClient.getAccessToken(code);
+  // 인가 코드를 이용해 카카오 로그인 API를 호출한다
+  public LoginResponse kakaoLogin(String code) {
+    // 1. 카카오에 인가 코드를 넘겨서 액세스 토큰을 획득한다
+    log.debug("----- 액세스 토큰 발급 -----");
+    final String accessToken = kakaoOAuthClient.getAccessToken(code);
 
-    // 2. 사용자 정보 요청
-    KakaoUserInfo userInfo = kakaoApiClient.getUserInfo(accessToken);
+    // 2. 카카오에 액세스 토큰을 넘겨서 카카오에 저장된 사용자 정보를 획득한다
+    log.debug("----- 사용자 정보 획득 -----");
+    final KakaoUserInfo userInfo = kakaoOAuthClient.getUserInfo(accessToken);
 
-    // 3. 회원 가입 또는 로그인 처리
-    User user = userRepository.findByEmail(userInfo.getEmail())
+    // 3. 해당 정보를 이용해 회원 가입 또는 로그인을 처리한다
+    log.debug("----- 회원 가입 또는 로그인 -----");
+    User user = userRepository.findByEmail(userInfo.kakaoAccount().email())
         .orElseGet(() -> registerUser(userInfo));
 
-    // 4. JWT 토큰 발급
-    return jwtUtil.createToken(user.getUsername());
+    // 4. 서비스 서버에 저장된 회원 정보를 이용해 JWT 토큰을 발급받는다
+    log.debug("----- JWT 토큰 발급 -----");
+    String token = jwtUtil.createToken(user.getUsername());
+
+    return new LoginResponse(token);
   }
 
   private User registerUser(KakaoUserInfo userInfo) {
-    User user = new User(userInfo.getEmail(), userInfo.getNickname(), Provider.KAKAO,
-        userInfo.getProviderId());
+    String username = "kakao" + userInfo.id();
+    String password = passwordEncoder.encode(username);
+    User user = new User(
+        userInfo.kakaoAccount().email(),
+        username,
+        password,
+        userInfo.kakaoAccount().profile().nickname(),
+        userInfo.kakaoAccount().profile().nickname(),
+        Role.USER,
+        Provider.KAKAO,
+        userInfo.id()
+    );
+    log.debug("--------------------회원 가입 메서드 실행--------------------");
+    log.debug("email: {}, username: {}, password: {}, name: {}, nickname: {}, id: {}",
+        userInfo.kakaoAccount().email(),
+        username,
+        password,
+        userInfo.kakaoAccount().profile().nickname(),
+        userInfo.kakaoAccount().profile().nickname(),
+        userInfo.id()
+    );
+
     return userRepository.save(user);
   }