AWS S3 with Java

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Working with S3 using AWS SDK for Java 2.x

Maven

See aws/aws-sdk-java-v2 on how to use AWS SDK Java V2.

Import the BOM. 

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<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>software.amazon.awssdk</groupId>
      <artifactId>bom</artifactId>
      <version>2.20.43</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

Import s3 dependency

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<!-- https://mvnrepository.com/artifact/software.amazon.awssdk/s3 -->
<dependency>
  <groupId>software.amazon.awssdk</groupId>
  <artifactId>s3</artifactId>
</dependency>

Create Client

You can create S3Client using builder() method.

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public S3Client s3Client() {
    return S3Client.builder()
        .region( Region.US_EAST_2)
        .build();
}

If you don’t provide the credentials provider, The default provider DefaultCredentialsProvider will be used.

S3Client is thread-safe. see S3Client Interface API. It has @ThreadSafe annotation.

To use static credentials when creating S3Client.

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public S3Client s3Client() {
    AwsBasicCredentials awsCreds = AwsBasicCredentials.create(
        "your_access_key_id",
        "your_secret_access_key");
    return S3Client.builder()
            .credentialsProvider(StaticCredentialsProvider.create(awsCreds))
            .region(Region.US_EAST_1)
            .build();
}

List All Buckets

listBuckets method returns a list of all buckets owned by the authenticated sender of the request.

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try {
    ListBucketsResponse response = s3Client.listBuckets();
    response.buckets().forEach(System.out::println);
} catch (S3Exception exception) {
    exception.printStackTrace();
}

List Objects in a Bucket

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try {
    ListObjectsRequest request = ListObjectsRequest
        .builder()
        .bucket("bucket-name")
        .build();
    ListObjectsResponse response = s3Client.listObjects(request);
    List<S3Object> contents = response.contents();
    contents.forEach(s3Object -> {
        System.out.printf("key: %s, size: %d \n", s3Object.key(), s3Object.size());
    });
} catch (S3Exception exception) {
    exception.printStackTrace();
}

Upload Object

putObject method is used to upload object to S3. it taks a PutObjectRequest and RequestBody as parameters.

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try {
    PutObjectRequest request = PutObjectRequest.builder()
            .bucket("bucket-name")
            .key("key/to/file")
            .build();
    RequestBody requestBody = RequestBody.fromString("{\"name\": \"hello\"}");
    s3Client.putObject(request, requestBody);
} catch (S3Exception exception) {
    exception.printStackTrace();
}

Get Object

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try {
    GetObjectRequest request = GetObjectRequest.builder()
            .bucket("bucket-name")
            .key("key/to/file")
            .build();
    try (ResponseInputStream<GetObjectResponse> objectAsBytes = s3Client.getObject(request)) {
        byte[] bytes = objectAsBytes.readAllBytes();
        String content = new String(bytes, "UTF-8");
        System.out.println(content);
    }
} catch (S3Exception | IOException exception) {
    exception.printStackTrace();
}

Delete Object

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try {
    DeleteObjectRequest deleteObjectRequest = DeleteObjectRequest.builder()
            .bucket("bucket-name")
            .key("key/to/file")
            .build();
    s3Client.deleteObject(deleteObjectRequest);
} catch (S3Exception e) {
    System.err.println(e.awsErrorDetails().errorMessage());
}

Close S3Clinet

When S3Client is no longer needed, call S3Client.close() method to close S3Client.

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s3Client.close();

Reference