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Amazon Web Services

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Robin Drew edited this page Mar 7, 2025 · 6 revisions

You can interact with AWS using their Java API. It covers most operations you might want to execute on AWS.

Setting up the Environment

You must provide the application with the AWS credentials and region to execute code against AWS. You can set these up as environment variables or provide them as system properties.

Description Environment Variable System Property
Access Key AWS_DEFAULT_REGION aws.accessKeyId
Secret Key AWS_SECRET_ACCESS_KEY aws.secretAccessKey
Session Token AWS_SESSION_TOKEN aws.sessionToken
Region AWS_DEFAULT_REGION or AWS_REGION aws.region

Regions

When interacting with services, you will typically only be doing so in a single region. For example to connect to:

  • London use eu-west-2
  • New York use us-east-1
  • San Francisco use us-west-1

For more information on regions and availability zones:

S3

The Simple Storage Service is a database. It is a fully elactic (scalable) object store.

Buckets

Objects are stored in buckets. A bucket is a mapping from keys (String) to data (bytes).

// Create a simple client
S3Client client = S3Client.builder().httpClientBuilder(ApacheHttpClient.builder()).build();

// Create a bucket
// (String bucketName)
client.createBucket(CreateBucketRequest.builder().bucket(bucketName).build());

// Delete a bucket
// (String bucketName)
client.deleteBucket(DeleteBucketRequest.builder().bucket(bucketName).build());

// Put data in the bucket
// (String bucketName, String key, RequestBody value)
client.putObject(PutObjectRequest.builder().bucket(bucketName).key(key).build(), value);

// Get data from a bucket
// (String bucketName, String key)
ResponseInputStream<GetObjectResponse> response = client.getObject(GetObjectRequest.builder().bucket(bucketName).key(key).build());

// Delete data in a bucket
// (String bucketName, String key)
client.deleteObject(DeleteObjectRequest.builder().bucket(name).key(key).build());

Store Data

The operation to store data putObject() first requires converting the data to a RequestBody object.

// There are a number of static utility methods to create a request body
RequestBody.empty();
RequestBody.fromBytes(byte[] bytes);
RequestBody.fromString(String text); // UTF-8
RequestBody.fromString(String text, Charset charset);
RequestBody.fromInputStream(InputStream stream, int length);
RequestBody.fromFile(File file);
RequestBody.fromFile(Path path);

Retrieve Data

When calling getObject() you can a couple of options of the response format:

// You can stream the response bytes back (streaming is always useful if the data is large)
try (ResponseInputStream<GetObjectResponse> response = client.getObject(request)) {
    // handle response here ...
}

// Alternatively you can read the response as bytes in to memory and then convert ...
ResponseBytes<GetObjectResponse> response = client.getObjectAsBytes(request);
response.asByteArray();
response.asUtf8String();
response.asString(UTF_8);
response.asByteBuffer();
response.asInputStream();

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