feat: 카카오 oauth token 받아오기 구현

server/src/main/java/sunflower/server/auth/api/KakaoMemberApiController.java

@@ -4,6 +4,7 @@
 import org.springframework.http.HttpStatus;
 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;
 import sunflower.server.application.SessionService;
 import sunflower.server.auth.application.KakaoMemberService;
@@ -22,4 +23,10 @@ public ResponseEntity<Void> login() {
                 .header("Location", uri)
                 .build();
     }
+
+    @GetMapping("/login/kakao/session")
+    public ResponseEntity<Void> authorize(@RequestParam("code") String code) {
+        kakaoMemberService.login(code);
+        return null;
+    }
 }

server/src/main/java/sunflower/server/auth/application/KakaoMemberService.java

@@ -2,25 +2,37 @@
 
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Service;
+import sunflower.server.auth.client.KakaoOAuthClient;
 
 @Service
 public class KakaoMemberService {
 
-    private String redirectURI;
-    private String restApiKey;
-    private String authCodeURI;
+    private final String redirectURI;
+    private final String restApiKey;
+    private final String authCodeURI;
+    private final String authTokenURI;
+    private final KakaoOAuthClient kakaoOAuthClient;
 
     public KakaoMemberService(
             @Value("${oauth.kakao.rest-api-key}") String restApiKey,
             @Value("${oauth.kakao.redirect-uri}") String redirectURI,
-            @Value("${oauth.kakao.auth-code-uri}") String authCodeURI
+            @Value("${oauth.kakao.auth-code-uri}") String authCodeURI,
+            @Value("${oauth.kakao.token-uri}") String authTokenURI,
+            final KakaoOAuthClient kakaoOAuthClient
     ) {
         this.redirectURI = redirectURI;
         this.restApiKey = restApiKey;
         this.authCodeURI = authCodeURI;
+        this.authTokenURI = authTokenURI;
+        this.kakaoOAuthClient = kakaoOAuthClient;
     }
 
     public String loginURI() {
         return String.format(authCodeURI, restApiKey, redirectURI);
     }
+
+    public String login(final String code) {
+        kakaoOAuthClient.login(authTokenURI, restApiKey, redirectURI, code);
+        return null;
+    }
 }

server/src/main/java/sunflower/server/auth/client/KakaoOAuthClient.java

@@ -0,0 +1,65 @@
+package sunflower.server.auth.client;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.stereotype.Component;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+import org.springframework.web.client.RestTemplate;
+import sunflower.server.auth.client.response.KakaoOAuthResponse;
+
+import java.util.Map;
+
+@Slf4j
+@Component
+public class KakaoOAuthClient {
+
+    private final ObjectMapper objectMapper = new ObjectMapper();
+    private static final String GRANT_TYPE = "authorization_code";
+    private final RestTemplate restTemplate;
+
+    public KakaoOAuthClient(final RestTemplate restTemplate) {
+        this.restTemplate = restTemplate;
+    }
+
+    public void login(final String authTokenURI, final String restApiKey, final String redirectURI, final String code) {
+        final String requestURI = authTokenURI;
+        HttpHeaders requestHeader = createRequestHeader();
+        final MultiValueMap<String, Object> requestBody = createRequestBody(restApiKey, redirectURI, code);
+        final HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(requestBody, requestHeader);
+
+        log.info("Request URI: {}", requestURI);
+        log.info("Request Headers: {}", requestHeader);
+        log.info("Request Parameters: {}", requestBody);
+
+        final KakaoOAuthResponse response = restTemplate.postForObject(requestURI, requestEntity, KakaoOAuthResponse.class);
+    }
+
+    private MultiValueMap<String, Object> createRequestBody(final String restApiKey, final String redirectURI, final String code) {
+        MultiValueMap<String, Object> requestBody = new LinkedMultiValueMap<>();
+
+        requestBody.add("grant_type", GRANT_TYPE);
+        requestBody.add("client_id", restApiKey);
+        requestBody.add("redirect_uri", redirectURI);
+        requestBody.add("code", code);
+
+        return requestBody;
+    }
+
+    private String convertToJson(final Map<String, Object> body) {
+        try {
+            return objectMapper.writeValueAsString(body);
+        } catch (JsonProcessingException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private HttpHeaders createRequestHeader() {
+        HttpHeaders requestHeader = new HttpHeaders();
+        requestHeader.set("Content-Type", "application/x-www-form-urlencoded");
+        return requestHeader;
+    }
+}

server/src/main/java/sunflower/server/auth/client/response/KakaoOAuthResponse.java

@@ -0,0 +1,30 @@
+package sunflower.server.auth.client.response;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.ToString;
+
+@ToString
+@Getter
+@NoArgsConstructor
+public class KakaoOAuthResponse {
+
+    @JsonProperty("access_token")
+    private String accessToken;
+
+    @JsonProperty("token_type")
+    private String tokenType;
+
+    @JsonProperty("refresh_token")
+    private String refreshToken;
+
+    @JsonProperty("expires_in")
+    private String expiresIn;
+
+    @JsonProperty("refresh_token_expires_in")
+    private String refreshTokenExpiresIn;
+
+    @JsonProperty("scope")
+    private String scope;
+}

server/src/main/java/sunflower/server/client/ApiOcrDownloadClient.java

@@ -25,7 +25,7 @@ public ApiOcrDownloadClient(
             @Value("${ocr.download-uri}") String appURI,
             @Value("${ocr.app-id}") String appId,
             @Value("${ocr.app-key}") String appKey,
-            RestTemplate restTemplate
+            final RestTemplate restTemplate
     ) {
         this.appURI = appURI;
         this.appId = appId;

server/src/test/resources/application.yml

@@ -13,3 +13,4 @@ oauth:
     redirect-uri: https://www.sunnybraille.com/login/kakao
     rest-api-key: rest-api-key
     auth-code-uri: auth-code-uri
+    token-uri: token-uri