Perform a multipart upload of an Amazon S3 object using an Amazon SDK

The code examples use the following imports.

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import software.amazon.awssdk.core.exception.SdkException;
import software.amazon.awssdk.core.sync.RequestBody;
import software.amazon.awssdk.services.s3.S3AsyncClient;
import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.model.CompletedMultipartUpload;
import software.amazon.awssdk.services.s3.model.CompletedPart;
import software.amazon.awssdk.services.s3.model.CreateMultipartUploadResponse;
import software.amazon.awssdk.services.s3.model.PutObjectResponse;
import software.amazon.awssdk.services.s3.model.UploadPartRequest;
import software.amazon.awssdk.services.s3.model.UploadPartResponse;
import software.amazon.awssdk.services.s3.waiters.S3Waiter;
import software.amazon.awssdk.transfer.s3.S3TransferManager;
import software.amazon.awssdk.transfer.s3.model.FileUpload;
import software.amazon.awssdk.transfer.s3.model.UploadFileRequest;

import java.io.IOException;
import java.io.RandomAccessFile;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.ByteBuffer;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.UUID;
import java.util.concurrent.CompletableFuture;

Use the S3 Transfer Manager on top of the Amazon CRT-based S3 client to transparently perform a multipart upload when the size of the content exceeds a threshold. The default threshold size is 8 MB.

    public void multipartUploadWithTransferManager(String filePath) {
        S3TransferManager transferManager = S3TransferManager.create();
        UploadFileRequest uploadFileRequest = UploadFileRequest.builder()
                .putObjectRequest(b -> b
                        .bucket(bucketName)
                        .key(key))
                .source(Paths.get(filePath))
                .build();
        FileUpload fileUpload = transferManager.uploadFile(uploadFileRequest);
        fileUpload.completionFuture().join();
        transferManager.close();
    }

Use the S3Client API to perform a multipart upload.

    public void multipartUploadWithS3Client(String filePath) {

        // Initiate the multipart upload.
        CreateMultipartUploadResponse createMultipartUploadResponse = s3Client.createMultipartUpload(b -> b
                .bucket(bucketName)
                .key(key));
        String uploadId = createMultipartUploadResponse.uploadId();

        // Upload the parts of the file.
        int partNumber = 1;
        List<CompletedPart> completedParts = new ArrayList<>();
        ByteBuffer bb = ByteBuffer.allocate(1024 * 1024 * 5); // 5 MB byte buffer

        try (RandomAccessFile file = new RandomAccessFile(filePath, "r")) {
            long fileSize = file.length();
            int position = 0;
            while (position < fileSize) {
                file.seek(position);
                int read = file.getChannel().read(bb);

                bb.flip(); // Swap position and limit before reading from the buffer.
                UploadPartRequest uploadPartRequest = UploadPartRequest.builder()
                        .bucket(bucketName)
                        .key(key)
                        .uploadId(uploadId)
                        .partNumber(partNumber)
                        .build();

                UploadPartResponse partResponse = s3Client.uploadPart(
                        uploadPartRequest,
                        RequestBody.fromByteBuffer(bb));

                CompletedPart part = CompletedPart.builder()
                        .partNumber(partNumber)
                        .eTag(partResponse.eTag())
                        .build();
                completedParts.add(part);

                bb.clear();
                position += read;
                partNumber++;
            }
        } catch (IOException e) {
            logger.error(e.getMessage());
        }

        // Complete the multipart upload.
        s3Client.completeMultipartUpload(b -> b
                .bucket(bucketName)
                .key(key)
                .uploadId(uploadId)
                .multipartUpload(CompletedMultipartUpload.builder().parts(completedParts).build()));
    }

Use the S3AsyncClient API with multipart support enabled to perform a multipart upload.

    public void multipartUploadWithS3AsyncClient(String filePath) {
        // Enable multipart support.
        S3AsyncClient s3AsyncClient = S3AsyncClient.builder()
                .multipartEnabled(true)
                .build();

        CompletableFuture<PutObjectResponse> response = s3AsyncClient.putObject(b -> b
                        .bucket(bucketName)
                        .key(key),
                Paths.get(filePath));

        response.join();
        logger.info("File uploaded in multiple 8 MiB parts using S3AsyncClient.");
    }