Download all objects in an Amazon Simple Storage Service (Amazon S3) bucket to a local directory

Use an S3TransferManager to download all S3 objects in the same S3 bucket. View the complete file and test.

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import software.amazon.awssdk.core.sync.RequestBody;
import software.amazon.awssdk.services.s3.model.ObjectIdentifier;
import software.amazon.awssdk.transfer.s3.S3TransferManager;
import software.amazon.awssdk.transfer.s3.model.CompletedDirectoryDownload;
import software.amazon.awssdk.transfer.s3.model.DirectoryDownload;
import software.amazon.awssdk.transfer.s3.model.DownloadDirectoryRequest;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.HashSet;
import java.util.Set;
import java.util.UUID;
import java.util.stream.Collectors;

    public Integer downloadObjectsToDirectory(S3TransferManager transferManager,
                                              String destinationPath, String bucketName) {
        DirectoryDownload directoryDownload =
            transferManager.downloadDirectory(DownloadDirectoryRequest.builder()
                .destination(Paths.get(destinationPath))
                .bucket(bucketName)
                .build());
        CompletedDirectoryDownload completedDirectoryDownload = directoryDownload.completionFuture().join();

        completedDirectoryDownload.failedTransfers().forEach(fail ->
            logger.warn("Object [{}] failed to transfer", fail.toString()));
        return completedDirectoryDownload.failedTransfers().size();
    }