AWS S3 Presigned URL file upload - Retain file name in bucket

Question

I am trying to upload files into S3 bucket using presigned PUT URL like below

String tempFileKey = UUID.randomUUID().toString();
    GeneratePresignedUrlRequest generatePresignedUrlRequest =
                    new GeneratePresignedUrlRequest(tempBucketName, tempFileKey)
                            .withMethod(HttpMethod.PUT)
                            .withExpiration(expiration);
    URL fileUrl = s3Client.generatePresignedUrl(generatePresignedUrlRequest);

The problem with above approach is if the user uploads a file named 'xyz.jpg', I am not able to retain the file name (or extension) in the s3 bucket. The file gets saved with the tempFileKey as name. I won't be knowing the file name or extension while creating the presigned url.

I tried using ${filename} as tempFilekey as suggested in Sending file direct from browser to S3 but changing file name but it is just getting saved under the name ${filename} (literally)

Answer 1

Object key is integral part of the pre-signed url and is required by the algorithm which generates the url:

• Authenticating Requests: Using Query Parameters (AWS Signature Version 4)

Thus, you can't change the key.