Feature/#41 깃허브 로그인 기능 구현

backend/emm-sale/src/main/java/com/emmsale/login/application/GithubClient.java

@@ -0,0 +1,49 @@
+package com.emmsale.login.application;
+
+import com.emmsale.login.application.dto.GithubAccessTokenRequest;
+import com.emmsale.login.application.dto.GithubAccessTokenResponse;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
+import org.springframework.stereotype.Component;
+import org.springframework.web.client.RestTemplate;
+
+@Component
+public class GithubClient {
+
+  @Value("${github.client.id}")
+  private String clientId;
+  @Value("${github.client.secret}")
+  private String clientSecret;
+  @Value("${github.url.access-token}")
+  private String accessTokenUrl;
+  @Value("${github.url.profile}")
+  private String profileUrl;
+
+  public String getAccessTokenFromGithub(final String code) {
+    final GithubAccessTokenRequest githubAccessTokenRequest = new GithubAccessTokenRequest(
+        code,
+        clientId,
+        clientSecret
+    );
+
+    final HttpHeaders headers = new HttpHeaders();
+    headers.add("Accept", MediaType.APPLICATION_JSON_VALUE);
+
+    final HttpEntity httpEntity = new HttpEntity(githubAccessTokenRequest, headers);
+    final RestTemplate restTemplate = new RestTemplate();
+
+    final String accessToken = restTemplate
+        .exchange(accessTokenUrl, HttpMethod.POST, httpEntity, GithubAccessTokenResponse.class)
+        .getBody()
+        .getAccessToken();
+
+    if (accessToken == null) {
+      //TODO: 커스텀 예외 정의
+      throw new IllegalArgumentException("code가 유효하지 않습니다.");
+    }
+    return accessToken;
+  }
+}

backend/emm-sale/src/main/java/com/emmsale/login/application/dto/GithubAccessTokenRequest.java

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+package com.emmsale.login.application.dto;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+
+@AllArgsConstructor
+@Getter
+public class GithubAccessTokenRequest {
+
+  private final String code;
+  @JsonProperty("client_id")
+  private final String clientId;
+  @JsonProperty("client_secret")
+  private final String clientSecret;
+}

backend/emm-sale/src/main/java/com/emmsale/login/application/dto/GithubAccessTokenResponse.java

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+package com.emmsale.login.application.dto;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import lombok.AccessLevel;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@AllArgsConstructor
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@Getter
+public class GithubAccessTokenResponse {
+
+  @JsonProperty("access_token")
+  private String accessToken;
+  @JsonProperty("token_type")
+  private String tokenType;
+  private String scope;
+  private String bearer;
+}