Spring Boot Login API 개발 1 - 카카오 로그인 연동

package com.whitepaek.api;

import com.jayway.jsonpath.ReadContext;
import com.whitepaek.api.request.AuthRequest;
import com.whitepaek.client.KakaoClient;
import com.whitepaek.service.AuthService;
import com.whitepaek.service.request.AuthServiceRequest;
import com.whitepaek.service.response.AuthResponse;
import lombok.RequiredArgsConstructor;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RequiredArgsConstructor
@RestController
public class AuthController {

    private final KakaoClient kakaoClient;
    private final AuthService authService;

    @PostMapping("/auth/authorize")
    public ResponseEntity<AuthResponse> authorize(@RequestBody AuthRequest authRequest) {

        ReadContext tokenAttributes = kakaoClient.getToken(authRequest.getCode()); // 카카오 인증 서버에 Token 발급 요청
        String accessToken = tokenAttributes.read("$.access_token");

        ReadContext userAttributes = kakaoClient.getUserInfo(accessToken); // 카카오 인증 서버에 로그인 사용자 정보 요청
        Long loginId = userAttributes.read("$.id");
        String nickname = userAttributes.read("$.kakao_account.profile.nickname");
        String profileImageUrl = userAttributes.read("$.kakao_account.profile.profile_image_url");

        AuthServiceRequest authServiceRequest = AuthServiceRequest.builder()
                .loginId(loginId)
                .nickname(nickname)
                .profileImageUrl(profileImageUrl)
                .build();
        AuthResponse authResponse = authService.authorizationProcess(authServiceRequest); // 로그인 사용자 인증 처리
        return ResponseEntity.ok(authResponse);
    }
}

package com.whitepaek.client;

import com.jayway.jsonpath.JsonPath;
import com.jayway.jsonpath.ReadContext;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Component;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestClient;

import java.util.Map;

@Slf4j
@Component
public class KakaoClient {

    private static final String AUTHORIZATION_GRANT_TYPE = "authorization_code";
    private static final String TOKEN_URI = "https://kauth.kakao.com/oauth/token";
    private static final String USER_INFO_URI = "https://kapi.kakao.com/v2/user/me";

    private final String clientId;
    private final String clientSecret;
    private final String redirectUri;

    private KakaoClient(
            @Value("${kakao.client-id}") String clientId,
            @Value("${kakao.client-secret}") String clientSecret,
            @Value("${kakao.redirect-uri}") String redirectUri
    ) {
        this.clientId = clientId;
        this.clientSecret = clientSecret;
        this.redirectUri = redirectUri;
    }

    /**
     * 카카오 토큰 발급 API
     * Ref. https://developers.kakao.com/docs/latest/ko/kakaologin/rest-api#request-token
     * @param code
     * @return
     */
    public ReadContext getToken(String code) {
        MultiValueMap<String, Object> params = new LinkedMultiValueMap<>();
        params.add("grant_type", AUTHORIZATION_GRANT_TYPE);
        params.add("client_id", clientId);
        params.add("redirect_uri", redirectUri);
        params.add("code", code);
        params.add("client_secret", clientSecret);
        var responseBody = RestClient.builder().build()
                .post()
                .uri(TOKEN_URI)
                .contentType(MediaType.APPLICATION_FORM_URLENCODED)
                .body(params)
                .retrieve()
                .body(Map.class);
        return JsonPath.parse(responseBody);
    }

    /**
     * 카카오 로그인 사용자 정보 조회 API
     * Ref. https://developers.kakao.com/docs/latest/ko/kakaologin/rest-api#req-user-info
     * @param accessToken
     * @return
     */
    public ReadContext getUserInfo(String accessToken) {
        var responseBody = RestClient.builder().build()
                .get()
                .uri(USER_INFO_URI)
                .header("Authorization", "Bearer " + accessToken)
                .retrieve()
                .body(Map.class);
        return JsonPath.parse(responseBody);
    }
}

kakao:
   client-id: bd378af8980a4744c2d2549b9a53329b # REST API 키
   client-secret: q0tg1TIEOKhhj99syFZQk52xwHsHVWul # Client Secret
   redirect-uri: http://localhost:3000/oauth/code/kakao # Redirect URI

package com.whitepaek.service;

import com.whitepaek.entity.Member;
import com.whitepaek.repository.MemberRepository;
import com.whitepaek.service.request.AuthServiceRequest;
import com.whitepaek.service.response.AuthResponse;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;

import java.util.Optional;

@RequiredArgsConstructor
@Service
public class AuthService {

    private final MemberRepository memberRepository;

    public AuthResponse authorizationProcess(AuthServiceRequest authServiceRequest) {
        Optional<Member> optionalMember = memberRepository.findByLoginTypeAndLoginId(authServiceRequest.getLoginType(), authServiceRequest.getLoginId());
        Member member;

        if (optionalMember.isPresent()) {
            // 기존 멤버
            member = optionalMember.get();
            member.login(authServiceRequest.getNickname(), authServiceRequest.getProfileImageUrl());
        } else {
            // 신규 멤버
            member = authServiceRequest.toEntity();
            memberRepository.save(member);
        }

        return AuthResponse.builder()
                .id(member.getId())
                .nickname(member.getNickname())
                .profileImageUrl(member.getProfileImageUrl())
                .build();
    }
}

https://kauth.kakao.com/oauth/authorize?client_id=bd378af8980a4744c2d2549b9a53329b&redirect_uri=http://localhost:3000/oauth/code/kakao&response_type=code

{
  "id": 1,
  "nickname": "whitepaek",
  "profileImageUrl": "http://t1.kakaocdn.net/account_images/default_profile.jpeg.twg.thumb.R640x640"
}