Sample configuration Spring-Cloud-AWS, File services and Controller

client-request.txt

#sample cli request using curl

curl -i -F name=original_file_name_travelling_to_aws.txt -F filedata=@dummy.jpg http://localhost:8080/upload

#This assumes you're running curl inside directory where 'dummy.jpg' is.
#aws final file name is returned inside S3Object.getKey()

Configuration.java

import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.services.s3.AmazonS3Client;
import org.springframework.cloud.aws.context.config.annotation.EnableContextCredentials;
import org.springframework.cloud.aws.context.config.annotation.EnableContextResourceLoader;
import org.springframework.cloud.aws.context.support.io.ResourceLoaderBeanPostProcessor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;

@Configuration
@EnableContextResourceLoader
@EnableContextCredentials
public class Configuration {

    //TODO: these values should be read from config
    private static final String ACCESS_KEY = "XXX";

    private static final String SECRET_KEY = "YYY";


    @Bean
    public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
    }

    @Bean
    public AmazonS3Client amazonS3Client() {
        return new AmazonS3Client(new BasicAWSCredentials(ACCESS_KEY, SECRET_KEY));
    }


    @Bean
    public ResourceLoaderBeanPostProcessor resourceLoaderBeanPostProcessor() {
        return new ResourceLoaderBeanPostProcessor(amazonS3Client());
    }

}

FileController.java

import com.amazonaws.services.s3.model.S3Object;
import com.amazonaws.util.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Controller
public class AbstractFileController {

    private static final Logger LOGGER = LoggerFactory.getLogger(AbstractFileController.class);

    @Autowired
    private FileUploadService fileUploadService;

    @Autowired
    private FileDownloadService fileDownloadService;

    @RequestMapping(value = "/upload", method = RequestMethod.POST)
    @ResponseBody
    public void uploadFile(@RequestParam("file") MultipartFile file, String bucketName) {
        S3Object s3Object = null;
        if (!file.isEmpty()) {
            LOGGER.debug("File name:" + file.getOriginalFilename());
            try {
                s3Object = fileUploadService.writeFile(file.getInputStream(), bucketName);
                LOGGER.debug("File uploaded with name:" + s3Object.getKey());
            } catch (IOException ioe) {
                LOGGER.debug(ioe.getMessage());
            }
        }
    }


    @RequestMapping(value = "/download", method = RequestMethod.GET)
    @ResponseBody
    public void downloadFile(@RequestParam("name") String awsFileName, HttpServletResponse response, String bucketName) {


        LOGGER.debug("Downloading file with name:" + awsFileName);

        try {
            addDownloadResponseHeaders(response, awsFileName);
            IOUtils.copy(fileDownloadService.readFile(awsFileName, bucketName), response.getOutputStream());

        } catch (IOException ioe) {
            LOGGER.debug(ioe.getMessage());
        }
    }

    private void addDownloadResponseHeaders(HttpServletResponse response, String clientKnownFileName) {
        response.setHeader("Content-type", "text/csv");//this use case is only for csv files
        response.setHeader("Content-Disposition", "attachment; filename=\"" + clientKnownFileName + "\"");
        response.setHeader("Content-Transfer-Encoding", "binary");
    }

}

FileDownloadService.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.stereotype.Service;

import java.io.IOException;
import java.io.InputStream;

@Service
public class FileDownloadServiceImpl {

    private static final String S3_PREFIX = "s3://";

    @Autowired
    private ResourceLoader resourceLoader;

    @Override
    public InputStream readFile(String fileName, String bucketName) throws IOException {
        Resource resource = this.resourceLoader.getResource(S3_PREFIX + bucketName + "/" + fileName);
        return resource.getInputStream();
    }

}

FileRemovalService.java

import com.amazonaws.services.s3.AmazonS3Client;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class FileRemovalServiceImpl implements FileRemovalService {

    private static final String S3_PREFIX = "s3://";

    @Autowired
    private AmazonS3Client amazonS3Client;

    @Override
    public void removeFile(String fileName, String bucketName) throws Exception {

        this.amazonS3Client.deleteObject(bucketName, fileName);
    }
}

FileUploadService.java

import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.services.s3.model.PutObjectRequest;
import com.amazonaws.services.s3.model.PutObjectResult;
import com.amazonaws.services.s3.model.S3Object;
import com.amazonaws.util.IOUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.io.WritableResource;
import org.springframework.stereotype.Service;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

@Service
public class FileUploadServiceImpl {

    private static final String S3_PREFIX = "s3://";

    @Autowired
    private ResourceLoader resourceLoader;

    @Autowired
    private AmazonS3Client amazonS3Client;


    public S3Object writeFile(File file, String bucketName) throws IOException {
        String uniqueFileName = FileUtils.generateRandomFileId();
        PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, uniqueFileName, file);
        PutObjectResult putObjectResult =  this.amazonS3Client.putObject(putObjectRequest);
        return this.amazonS3Client.getObject(bucketName, uniqueFileName);
    }

    public S3Object writeFile(InputStream is, String bucketName) throws IOException {

        String uniqueFileName = FileUtils.generateRandomFileId();

        Resource resource = this.resourceLoader.getResource(S3_PREFIX + bucketName + "/" + uniqueFileName);

        WritableResource writableResource = (WritableResource) resource;
        try (OutputStream outputStream = writableResource.getOutputStream()) {
            outputStream.write(IOUtils.toByteArray(is));
        }
        return this.amazonS3Client.getObject(bucketName, uniqueFileName);
    }
}

FileUtils.java

import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.util.UUID;

public class FileUtils {

    private static String UNDERSCORE = "_";

    public static String generateRandomFileId() {
        return new StringBuilder()
                .append(UUID.randomUUID().toString())
                .append(UNDERSCORE)
                .append(ZonedDateTime.now(ZoneId.of("UTC")))
                .toString();
    }

    public static String generateRandomFileId(String fileName) {
        return new StringBuilder()
                .append(fileName)
                .append(UNDERSCORE)
                .append(UUID.randomUUID().toString())
                .append(UNDERSCORE)
                .append(ZonedDateTime.now(ZoneId.of("UTC")))
                .toString();
    }
}