perform a few simple operations with the Amazon DynamoDB service.

Description

Demo Code

/*//from   www  .  j  a  va2 s  . c  o  m
 * Copyright 2012 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */
import java.util.HashMap;
import java.util.Map;

import com.amazonaws.AmazonClientException;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.PropertiesCredentials;
import com.amazonaws.services.dynamodb.AmazonDynamoDBClient;
import com.amazonaws.services.dynamodb.model.AttributeValue;
import com.amazonaws.services.dynamodb.model.ComparisonOperator;
import com.amazonaws.services.dynamodb.model.Condition;
import com.amazonaws.services.dynamodb.model.CreateTableRequest;
import com.amazonaws.services.dynamodb.model.DescribeTableRequest;
import com.amazonaws.services.dynamodb.model.KeySchema;
import com.amazonaws.services.dynamodb.model.KeySchemaElement;
import com.amazonaws.services.dynamodb.model.ProvisionedThroughput;
import com.amazonaws.services.dynamodb.model.PutItemRequest;
import com.amazonaws.services.dynamodb.model.PutItemResult;
import com.amazonaws.services.dynamodb.model.ScanRequest;
import com.amazonaws.services.dynamodb.model.ScanResult;
import com.amazonaws.services.dynamodb.model.TableDescription;
import com.amazonaws.services.dynamodb.model.TableStatus;

/**
 * This sample demonstrates how to perform a few simple operations with the
 * Amazon DynamoDB service.
 */
public class AmazonDynamoDBSample {

    /*
     * Important: Be sure to fill in your AWS access credentials in the
     *            AwsCredentials.properties file before you try to run this
     *            sample.
     * http://aws.amazon.com/security-credentials
     */

    static AmazonDynamoDBClient dynamoDB;

    /**
     * The only information needed to create a client are security credentials
     * consisting of the AWS Access Key ID and Secret Access Key. All other
     * configuration, such as the service endpoints, are performed
     * automatically. Client parameters, such as proxies, can be specified in an
     * optional ClientConfiguration object when constructing a client.
     *
     * @see com.amazonaws.auth.BasicAWSCredentials
     * @see com.amazonaws.auth.PropertiesCredentials
     * @see com.amazonaws.ClientConfiguration
     */
    private static void init() throws Exception {
        AWSCredentials credentials = new PropertiesCredentials(
                AmazonDynamoDBSample.class
                        .getResourceAsStream("AwsCredentials.properties"));

        dynamoDB = new AmazonDynamoDBClient(credentials);
    }

    public static void main(String[] args) throws Exception {
        init();

        try {
            String tableName = "my-favorite-movies-table";

            // Create a table with a primary key named 'name', which holds a string
            CreateTableRequest createTableRequest = new CreateTableRequest()
                    .withTableName(tableName)
                    .withKeySchema(
                            new KeySchema(new KeySchemaElement()
                                    .withAttributeName("name")
                                    .withAttributeType("S")))
                    .withProvisionedThroughput(
                            new ProvisionedThroughput()
                                    .withReadCapacityUnits(10L)
                                    .withWriteCapacityUnits(10L));
            TableDescription createdTableDescription = dynamoDB
                    .createTable(createTableRequest).getTableDescription();
            System.out.println("Created Table: " + createdTableDescription);

            // Wait for it to become active
            waitForTableToBecomeAvailable(tableName);

            // Describe our new table
            DescribeTableRequest describeTableRequest = new DescribeTableRequest()
                    .withTableName(tableName);
            TableDescription tableDescription = dynamoDB.describeTable(
                    describeTableRequest).getTable();
            System.out.println("Table Description: " + tableDescription);

            // Add an item
            Map<String, AttributeValue> item = newItem(
                    "Bill & Ted's Excellent Adventure", 1989, "****",
                    "James", "Sara");
            PutItemRequest putItemRequest = new PutItemRequest(tableName,
                    item);
            PutItemResult putItemResult = dynamoDB.putItem(putItemRequest);
            System.out.println("Result: " + putItemResult);

            // Add another item
            item = newItem("Airplane", 1980, "*****", "James", "Billy Bob");
            putItemRequest = new PutItemRequest(tableName, item);
            putItemResult = dynamoDB.putItem(putItemRequest);
            System.out.println("Result: " + putItemResult);

            // Scan items for movies with a year attribute greater than 1985
            HashMap<String, Condition> scanFilter = new HashMap<String, Condition>();
            Condition condition = new Condition().withComparisonOperator(
                    ComparisonOperator.GT.toString())
                    .withAttributeValueList(
                            new AttributeValue().withN("1985"));
            scanFilter.put("year", condition);
            ScanRequest scanRequest = new ScanRequest(tableName)
                    .withScanFilter(scanFilter);
            ScanResult scanResult = dynamoDB.scan(scanRequest);
            System.out.println("Result: " + scanResult);

        } catch (AmazonServiceException ase) {
            System.out
                    .println("Caught an AmazonServiceException, which means your request made it "
                            + "to AWS, but was rejected with an error response for some reason.");
            System.out.println("Error Message:    " + ase.getMessage());
            System.out.println("HTTP Status Code: " + ase.getStatusCode());
            System.out.println("AWS Error Code:   " + ase.getErrorCode());
            System.out.println("Error Type:       " + ase.getErrorType());
            System.out.println("Request ID:       " + ase.getRequestId());
        } catch (AmazonClientException ace) {
            System.out
                    .println("Caught an AmazonClientException, which means the client encountered "
                            + "a serious internal problem while trying to communicate with AWS, "
                            + "such as not being able to access the network.");
            System.out.println("Error Message: " + ace.getMessage());
        }
    }

    private static Map<String, AttributeValue> newItem(String name,
            int year, String rating, String... fans) {
        Map<String, AttributeValue> item = new HashMap<String, AttributeValue>();
        item.put("name", new AttributeValue(name));
        item.put("year", new AttributeValue().withN(Integer.toString(year)));
        item.put("rating", new AttributeValue(rating));
        item.put("fans", new AttributeValue().withSS(fans));

        return item;
    }

    private static void waitForTableToBecomeAvailable(String tableName) {
        System.out.println("Waiting for " + tableName
                + " to become ACTIVE...");

        long startTime = System.currentTimeMillis();
        long endTime = startTime + (10 * 60 * 1000);
        while (System.currentTimeMillis() < endTime) {
            try {
                Thread.sleep(1000 * 20);
            } catch (Exception e) {
            }
            try {
                DescribeTableRequest request = new DescribeTableRequest()
                        .withTableName(tableName);
                TableDescription tableDescription = dynamoDB.describeTable(
                        request).getTable();
                String tableStatus = tableDescription.getTableStatus();
                System.out.println("  - current state: " + tableStatus);
                if (tableStatus.equals(TableStatus.ACTIVE.toString()))
                    return;
            } catch (AmazonServiceException ase) {
                if (ase.getErrorCode().equalsIgnoreCase(
                        "ResourceNotFoundException") == false)
                    throw ase;
            }
        }

        throw new RuntimeException("Table " + tableName
                + " never went active");
    }

}
perform a few simple operations with the Amazon DynamoDB service. - Java AWS

Description

Demo Code

Related Tutorials
