feat(resources): google 관련 설정 추가

Author: kaswhy

gdgoc/src/main/java/inha/gdgoc/domain/user/controller/AuthController.java

@@ -0,0 +1,28 @@
+package inha.gdgoc.domain.user.controller;
+
+import inha.gdgoc.domain.user.service.GoogleOAuthService;
+import inha.gdgoc.global.common.ApiResponse;
+import jakarta.servlet.http.HttpServletResponse;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+@RequestMapping("/auth/oauth2")
+@RestController
+@RequiredArgsConstructor
+public class AuthController {
+
+    private final GoogleOAuthService googleOAuthService;
+
+    @GetMapping("/google/callback")
+    public ResponseEntity<ApiResponse<?>> handleGoogleCallback(
+            @RequestParam String code,
+            HttpServletResponse response
+    ) {
+        googleOAuthService.processOAuthLogin(code, response);
+        return ResponseEntity.ok(ApiResponse.success("code 받기 성공"));
+    }
+}

gdgoc/src/main/java/inha/gdgoc/domain/user/service/GoogleOAuthService.java

@@ -0,0 +1,68 @@
+package inha.gdgoc.domain.user.service;
+
+import org.springframework.beans.factory.annotation.Value;
+import inha.gdgoc.domain.user.repository.UserRepository;
+import jakarta.servlet.http.HttpServletResponse;
+import java.util.Map;
+import lombok.RequiredArgsConstructor;
+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.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+import org.springframework.web.client.RestTemplate;
+
+@Service
+@RequiredArgsConstructor
+public class GoogleOAuthService {
+
+    @Value("${google.client-id}")
+    private String clientId;
+
+    @Value("${google.client-secret}")
+    private String clientSecret;
+
+    @Value("${google.redirect-uri}")
+    private String redirectUri;
+
+    private final UserRepository userRepository;
+
+    private final RestTemplate restTemplate = new RestTemplate();
+
+    public void processOAuthLogin(String code, HttpServletResponse response) {
+        // 1. code → access token 요청
+        HttpHeaders headers = new HttpHeaders();
+        headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
+
+        MultiValueMap<String, String> params = new LinkedMultiValueMap<>();
+        params.add("code", code);
+        params.add("client_id", clientId);
+        params.add("client_secret", clientSecret);
+        params.add("redirect_uri", redirectUri);
+        params.add("grant_type", "authorization_code");
+
+        HttpEntity<MultiValueMap<String, String>> tokenRequest = new HttpEntity<>(params, headers);
+        ResponseEntity<Map> tokenResponse = restTemplate.postForEntity(
+                "https://oauth2.googleapis.com/token",
+                tokenRequest,
+                Map.class
+        );
+
+        String accessToken = (String) tokenResponse.getBody().get("access_token");
+
+        // 2. access token → 사용자 정보 요청
+        HttpHeaders userInfoHeaders = new HttpHeaders();
+        userInfoHeaders.setBearerAuth(accessToken);
+        HttpEntity<Void> userInfoRequest = new HttpEntity<>(userInfoHeaders);
+
+        ResponseEntity<Map> userInfoResponse = restTemplate.exchange(
+                "https://www.googleapis.com/oauth2/v2/userinfo",
+                HttpMethod.GET,
+                userInfoRequest,
+                Map.class
+        );
+    }
+}