Amazon Dynamo DB Connect

package in.net.cadentic.core.database;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.client.builder.AwsClientBuilder;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder;

/**
 * The Singleton Class AmazonDynamoDBClientHandler - creates and manages the
 * client instance and all its Amazon AWS API calls.
 *
 *
 * @author Sandeep
 * @version 1.0
 * @see {@link https://docs.aws.amazon.com/general/latest/gr/ddb.html}
 * @see {@link https://sdk-for-java.amazonwebservices.com/latest/aws-java-sdk.zip}
 */
public class AmazonDynamoDBClientHandler {

    /** The Constant PROPERTIES_FILE. */
    private static final String PROPERTIES_FILE = "aws.properties";

    /** The Constant PROPERTIES. */
    private static final Properties PROPERTIES = new Properties();

    /** The Constant AWS_ACCESS_KEYID. */
    private static final String AWS_ACCESS_KEYID = "AWSAccessKeyId";

    /** The Constant AWS_Secret_KEY. */
    private static final String AWS_Secret_KEY = "AWSSecretKey";

    /** The Constant SERVICE_END_POINT. */
    private static final String SERVICE_END_POINT = "serviceEndPoint";

    /** The Constant SIGNING_REGION. */
    private static final String SIGNING_REGION = "signingRegion";

    /** The AmazonDynamoDB */
    private AmazonDynamoDB amazonDynamoDB = null;

    /**
     * Instantiates a new AmazonDynamoDBClientHandler.
     */
    private AmazonDynamoDBClientHandler() {
    }

    /**
     * Gets the single instance of AmazonDynamoDBClientHandler.
     *
     * @return single instance of AmazonDynamoDBClientHandler
     */
    public static AmazonDynamoDBClientHandler getNewInstance() {
        return new AmazonDynamoDBClientHandler();
    }

    /**
     * Creates a new Amazon AWS DynamoDB client.
     *
     * @return the Amazon AWS DynamoDB client
     * @throws IOException
     */
    public AmazonDynamoDB createNewClient() throws IOException {

        // ClassLoader classLoader = Thread.currentThread().getContextClassLoader();

        // final ClassLoader classLoader = getClass().getClassLoader();

        InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream(PROPERTIES_FILE);

        PROPERTIES.load(inputStream);

        if (amazonDynamoDB == null) {
            amazonDynamoDB = AmazonDynamoDBClientBuilder.standard()
                    .withEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration(
                            PROPERTIES.getProperty(SERVICE_END_POINT), PROPERTIES.getProperty(SIGNING_REGION)))
                    .withCredentials(new AWSStaticCredentialsProvider(new AWSCredentials() {
                        @Override
                        public String getAWSAccessKeyId() {
                            return PROPERTIES.getProperty(AWS_ACCESS_KEYID);
                        }

                        @Override
                        public String getAWSSecretKey() {
                            return PROPERTIES.getProperty(AWS_Secret_KEY);
                        }
                    })).build();
        }
        return amazonDynamoDB;
    }

    /**
     * Shuts down client instance releasing any resources that might be held open.
     *
     */
    public void shutdownClient() {
        amazonDynamoDB.shutdown();
    }
}