difference between Interface S3Client and Class AmazonS3Client - amazon-web-services

Question

I am creating a method that needs a S3 client as a parameter. I do not know what type should I declare it to be.
this is the doc for S3Client https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/services/s3/S3Client.html
Ignore since answered (this is the doc for AmazonS3Client
https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/services/s3/AmazonS3Client.html My question is which type is recommended and what are difference between them? Thank you! )
Update:
I find another S3 Client here: AmazonS3 interface.
https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/services/s3/AmazonS3.html
However, setObjectTagging is supported in type AmazonS3 not but in type S3Client .
Does AmazonS3 provide more functionality than S3Client?
What if I need some function in AmazonS3 not in S3Client, or some in S3Client not in AmazonS3?

Answer 1

The AWS SDK for Java has two versions: V1 and V2. AmazonS3Client is the older V1 version while S3Client is the newer V2 version.
Amazon recommends using V2:
The AWS SDK for Java 2.x is a major rewrite of the version 1.x code base. It’s built on top of Java 8+ and adds several frequently requested features. These include support for non-blocking I/O and the ability to plug in a different HTTP implementation at run time.
You can find Amazon S3 V2 code examples in the Java Developer V2 DEV Guide here:
Developer guide - AWS SDK for Java 2.x
(At this point, the Amazon S3 Service guide does not have V2 examples in it.)
In addition, you can find all Amazon S3 V2 code examples in AWS Github here:
https://github.com/awsdocs/aws-doc-sdk-examples/tree/master/javav2/example_code/s3
If you are not familiar developing apps by using the AWS SDK for Java V2, it's recommended that you start here:
Get started with the AWS SDK for Java 2.x
(This getting started topic happens to use the Amazon S3 Java V2 API to help get you up and running with using the AWS SDK for Java V2)
Update:
You stated: However, setObjectTagging is supported in type AmazonS3 not but in type S3Client .
The way to tag an Object in an Amazon S3 bucket by using Java V2 API is to use this code:
// First need to get existing tag set; otherwise the existing tags are overwritten.
GetObjectTaggingRequest getObjectTaggingRequest = GetObjectTaggingRequest.builder()
.bucket(bucketName)
.key(key)
.build();
GetObjectTaggingResponse response = s3.getObjectTagging(getObjectTaggingRequest);
// Get the existing immutable list - cannot modify this list.
List<Tag> existingList = response.tagSet();
ArrayList<Tag> newTagList = new ArrayList(new ArrayList<>(existingList));
// Create a new tag.
Tag myTag = Tag.builder()
.key(label)
.value(LabelValue)
.build();
// push new tag to list.
newTagList.add(myTag);
Tagging tagging = Tagging.builder()
.tagSet(newTagList)
.build();
PutObjectTaggingRequest taggingRequest = PutObjectTaggingRequest.builder()
.key(key)
.bucket(bucketName)
.tagging(tagging)
.build();
s3.putObjectTagging(taggingRequest);