AWS s3 file upload in parts [java]

s3fileUpload.java

   private File multipartToFile(MultipartFile multipartFile) {
        File file = new File(multipartFile.getOriginalFilename());
        try {
            multipartFile.transferTo(file);
            return file;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

    private void uploadInParts(String bucketForUpload, String fullPathOfFile, ObjectMetadata metadata, MultipartFile file) {
        // <-------------------------------------------------------------->
        // <-------------------------------------------------------------->
        // <-------------------------------------------------------------->
        // Create a list of UploadPartResponse objects. You get one of these for
        // each part uploadFiles.
        List<PartETag> partETags = new ArrayList<>();
        // <-------------------------------------------------------------->
        // Step 1: Initialize.
        InitiateMultipartUploadRequest initRequest = new InitiateMultipartUploadRequest(
                bucketForUpload, fullPathOfFile, metadata);
        InitiateMultipartUploadResult initResponse =
                amazonS3.initiateMultipartUpload(initRequest);

        File file1 = multipartToFile(file);
        // if cannot convert multipartFile to File
        if (file1 == null) {
            log.error("Fuck!");
            return;
        }
        long contentLength = file1.length();
        long partSize = 5 * 1024 * 1024; // set part size to 5 MB

        // <-------------------------------------------------------------->
        // <-------------------------------------------------------------->
        // <-------------------------------------------------------------->
        try {
            // Step 2: Upload parts.
            long filePosition = 0;
            for (int i = 1; filePosition < contentLength; i++) {
                // Last part can be less than 5 MB. Adjust part size.
                partSize = Math.min(partSize, (contentLength - filePosition));

                // Create request to uploadFiles a part.
                UploadPartRequest uploadRequest = new UploadPartRequest()
                        .withBucketName(bucketForUpload).withKey(fullPathOfFile)
                        .withUploadId(initResponse.getUploadId()).withPartNumber(i)
                        .withFileOffset(filePosition)
                        .withFile(file1)
                        .withPartSize(partSize);

                // Upload part and add response to our list.
                partETags.add(amazonS3.uploadPart(uploadRequest).getPartETag());

                filePosition += partSize;
            }

            // Step 3: Complete.
            CompleteMultipartUploadRequest compRequest = new
                    CompleteMultipartUploadRequest(
                    bucketForUpload,
                    fullPathOfFile,
                    initResponse.getUploadId(),
                    partETags);

            amazonS3.completeMultipartUpload(compRequest);
        } catch (Exception e) {
            amazonS3.abortMultipartUpload(new AbortMultipartUploadRequest(
                    bucketForUpload, fullPathOfFile, initResponse.getUploadId()));
        }
        // <-------------------------------------------------------------->
        // <-------------------------------------------------------------->
        // <-------------------------------------------------------------->
    }