Use DownloadDirectory with an Amazon SDK or command line tool

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.net.URI;
import java.net.URISyntaxException;
import java.nio.file.Files;
import java.nio.file.Path;
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,
            URI destinationPathURI, String bucketName) {
        DirectoryDownload directoryDownload = transferManager.downloadDirectory(DownloadDirectoryRequest.builder()
                .destination(Paths.get(destinationPathURI))
                .bucket(bucketName)
                .build());
        CompletedDirectoryDownload completedDirectoryDownload = directoryDownload.completionFuture().join();

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