How to set the content type of an S3 object via the SDK?

Question

I'm trying to use AWS Api to set the content type of multiple objects and to add a 'content-encoding: gzip' header to them. Here's my code for doing that:

for (S3ObjectSummary summary : objs.getObjectSummaries() )
   {
       String key = summary.getKey();
       if (! key.endsWith(".gz"))
           continue;

       ObjectMetadata metadata = new ObjectMetadata();
       metadata.addUserMetadata("Content-Encoding", "gzip");
       metadata.addUserMetadata("Content-Type", "application/x-gzip");
       final CopyObjectRequest request = new CopyObjectRequest(bucket, key, bucket, key)
               .withSourceBucketName( bucket )
               .withSourceKey(key)
               .withNewObjectMetadata(metadata);

       s3.copyObject(request);
   }

When I run this however, the following is the result:

As you can see, the prefix x-amz-meta was added to my custom headers, and they were lower cased. And the content-type header was ignored, instead it put www/form-encoded as the header.

What can I do it to cause it to accept my header values?

Answer 1

Found the problem. ObjectMetadata requires the content-type / encoding to be set explicitly rather than via addUserMetadata(). Changing the following:

   metadata.addUserMetadata("Content-Encoding", "gzip");
   metadata.addUserMetadata("Content-Type", "application/x-gzip");

to:

       metadata.setContentEncoding("gzip");
       metadata.setContentType("application/x-gzip");

fixed this.

Answer 2

In SDK V2, use:

PutObjectRequest.builder() 
...
.contentType(contentType)
.build()