Determine the existence and content type of an object in an Amazon S3 bucket using an Amazon SDK

Determine the content type of an object.

    public static void getContentType (S3Client s3, String bucketName, String keyName) {

        try {
            HeadObjectRequest objectRequest = HeadObjectRequest.builder()
                .key(keyName)
                .bucket(bucketName)
                .build();

            HeadObjectResponse objectHead = s3.headObject(objectRequest);
            String type = objectHead.contentType();
            System.out.println("The object content type is "+type);

        } catch (S3Exception e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }

Get the restore status of an object.

    public static void checkStatus(S3Client s3, String bucketName, String keyName) {
        try {
            HeadObjectRequest headObjectRequest = HeadObjectRequest.builder()
                .bucket(bucketName)
                .key(keyName)
                .build();

            HeadObjectResponse response = s3.headObject(headObjectRequest);
            System.out.println("The Amazon S3 object restoration status is "+response.restore());

        } catch (S3Exception e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }

require "aws-sdk-s3"

# Wraps Amazon S3 object actions.
class ObjectExistsWrapper
  attr_reader :object

  # @param object [Aws::S3::Object] An Amazon S3 object.
  def initialize(object)
    @object = object
  end

  # Checks whether the object exists.
  #
  # @return [Boolean] True if the object exists; otherwise false.
  def exists?
    @object.exists?
  rescue Aws::Errors::ServiceError => e
    puts "Couldn't check existence of object #{@object.bucket.name}:#{@object.key}. Here's why: #{e.message}"
    false
  end
end

# Replace bucket name and object key with an existing bucket and object that you own.
def run_demo
  bucket_name = "doc-example-bucket"
  object_key = "my-object.txt"

  wrapper = ObjectExistsWrapper.new(Aws::S3::Object.new(bucket_name, object_key))
  exists = wrapper.exists?

  puts "Object #{object_key} #{exists ? 'does' : 'does not'} exist."
end

run_demo if $PROGRAM_NAME == __FILE__