[SpringBoot] Spring Boot에서 Google Drive에 파일을 업로드

import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp;
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.util.store.FileDataStoreFactory;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.File;
import org.springframework.web.multipart.MultipartFile;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.GeneralSecurityException;
import java.util.Collections;
import java.util.List;

public class GoogleDriveFileUploadExample {
    private static final String APPLICATION_NAME = "Google Drive API Java Quickstart";
    private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    private static final String TOKENS_DIRECTORY_PATH = "tokens";

    private static final List<String> SCOPES = Collections.singletonList(DriveScopes.DRIVE_FILE);
    private static final String CREDENTIALS_FILE_PATH = "/credentials.json";

    public static void uploadFile(MultipartFile file) throws IOException, GeneralSecurityException {
        NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
        Drive service = new Drive.Builder(HTTP_TRANSPORT, JSON_FACTORY, getCredentials(HTTP_TRANSPORT))
                .setApplicationName(APPLICATION_NAME)
                .build();

        File fileMetadata = new File();
        fileMetadata.setName(file.getOriginalFilename());

        InputStream inputStream = file.getInputStream();
        File uploadedFile = service.files().create(fileMetadata, inputStream, file.getContentType()).execute();

        System.out.println("File ID: " + uploadedFile.getId());
    }

	private static Credential getCredentials(final NetHttpTransport HTTP_TRANSPORT) throws IOException {
        InputStream in = GoogleDriveFileUploadExample.class.getResourceAsStream(CREDENTIALS_FILE_PATH);
        GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));

        GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
                HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
                .setDataStoreFactory(new FileDataStoreFactory(new java.io.File(TOKENS_DIRECTORY_PATH)))
                .setAccessType("offline")
                .build();
        LocalServerReceiver receiver = new LocalServerReceiver.Builder().setPort(8888).build();
        return new AuthorizationCodeInstalledApp(flow, receiver).authorize("user");
	}
}

Google Drive API에 연결하는 데 필요한 인증 정보를 가져옵니다. CREDENTIALS_FILE_PATH 변수에서 구글 개발자 콘솔에서 다운로드한 credentials.json 파일을 읽어들입니다.