LowLevelMultipartUpload.java

// Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: MIT-0 (For details, see https://github.com/awsdocs/amazon-s3-developer-guide/blob/master/LICENSE-SAMPLECODE.)

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import com.amazonaws.AmazonServiceException;
import com.amazonaws.SdkClientException;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.CompleteMultipartUploadRequest;
import com.amazonaws.services.s3.model.InitiateMultipartUploadRequest;
import com.amazonaws.services.s3.model.InitiateMultipartUploadResult;
import com.amazonaws.services.s3.model.PartETag;
import com.amazonaws.services.s3.model.UploadPartRequest;
import com.amazonaws.services.s3.model.UploadPartResult;

public class LowLevelMultipartUpload {

    public static void main(String[] args) throws IOException {
        String clientRegion = "*** Client region ***";
        String bucketName = "*** Bucket name ***";
        String keyName = "*** Key name ***";
        String filePath = "*** Path to file to upload ***";
        
        File file = new File(filePath);
        long contentLength = file.length();
        long partSize = 5 * 1024 * 1024; // Set part size to 5 MB. 

        try {
            AmazonS3 s3Client = AmazonS3ClientBuilder.standard()
                                    .withRegion(clientRegion)
                                    .withCredentials(new ProfileCredentialsProvider())
                                    .build();
                       
            // Create a list of ETag objects. You retrieve ETags for each object part uploaded,
            // then, after each individual part has been uploaded, pass the list of ETags to 
            // the request to complete the upload.
            List<PartETag> partETags = new ArrayList<PartETag>();

            // Initiate the multipart upload.
            InitiateMultipartUploadRequest initRequest = new InitiateMultipartUploadRequest(bucketName, keyName);
            InitiateMultipartUploadResult initResponse = s3Client.initiateMultipartUpload(initRequest);

            // Upload the file parts.
            long filePosition = 0;
            for (int i = 1; filePosition < contentLength; i++) {
                // Because the last part could be less than 5 MB, adjust the part size as needed.
                partSize = Math.min(partSize, (contentLength - filePosition));

                // Create the request to upload a part.
                UploadPartRequest uploadRequest = new UploadPartRequest()
                        .withBucketName(bucketName)
                        .withKey(keyName)
                        .withUploadId(initResponse.getUploadId())
                        .withPartNumber(i)
                        .withFileOffset(filePosition)
                        .withFile(file)
                        .withPartSize(partSize);

                // Upload the part and add the response's ETag to our list.
                UploadPartResult uploadResult = s3Client.uploadPart(uploadRequest);
                partETags.add(uploadResult.getPartETag());

                filePosition += partSize;
            }

            // Complete the multipart upload.
            CompleteMultipartUploadRequest compRequest = new CompleteMultipartUploadRequest(bucketName, keyName,
                    initResponse.getUploadId(), partETags);
            s3Client.completeMultipartUpload(compRequest);
        }
        catch(AmazonServiceException e) {
            // The call was transmitted successfully, but Amazon S3 couldn't process 
            // it, so it returned an error response.
            e.printStackTrace();
        }
        catch(SdkClientException e) {
            // Amazon S3 couldn't be contacted for a response, or the client
            // couldn't parse the response from Amazon S3.
            e.printStackTrace();
        }
    }
}