Java tutorial
package com.cloudkon.remote.worker; import java.io.FileInputStream; import java.io.InputStream; /* * Copyright 2012-2016 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.auth.AWSCredentials; import com.amazonaws.auth.PropertiesCredentials; import com.amazonaws.regions.Region; import com.amazonaws.regions.Regions; import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient; import com.amazonaws.services.dynamodbv2.model.AttributeDefinition; import com.amazonaws.services.dynamodbv2.model.AttributeValue; import com.amazonaws.services.dynamodbv2.model.ComparisonOperator; import com.amazonaws.services.dynamodbv2.model.Condition; import com.amazonaws.services.dynamodbv2.model.CreateTableRequest; import com.amazonaws.services.dynamodbv2.model.DescribeTableRequest; import com.amazonaws.services.dynamodbv2.model.KeySchemaElement; import com.amazonaws.services.dynamodbv2.model.KeyType; import com.amazonaws.services.dynamodbv2.model.ProvisionedThroughput; import com.amazonaws.services.dynamodbv2.model.PutItemRequest; import com.amazonaws.services.dynamodbv2.model.PutItemResult; import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType; import com.amazonaws.services.dynamodbv2.model.ScanRequest; import com.amazonaws.services.dynamodbv2.model.ScanResult; import com.amazonaws.services.dynamodbv2.model.TableDescription; import com.amazonaws.services.dynamodbv2.util.Tables; /** * This sample demonstrates how to perform a few simple operations with the * Amazon DynamoDB service. */ @SuppressWarnings("deprecation") public class Dynamodb { private String tableName; /* * WARNING: * To avoid accidental leakage of your credentials, DO NOT keep * the credentials file in your source directory. */ 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.ProfilesConfigFile * @see com.amazonaws.ClientConfiguration */ public static void init() { /* * Load the credentials */ AWSCredentials credentials = null; try { //InputStream credentialsFile = Dynamodb.class.getResourceAsStream("awsSecuCredentials.properties"); InputStream credentialsFile = new FileInputStream("./awsSecuCredentials.properties"); credentials = new PropertiesCredentials(credentialsFile); } catch (Exception e) { throw new AmazonClientException("Cannot load the credentials from the credential file. ", e); } dynamoDB = new AmazonDynamoDBClient(credentials); Region usEast1 = Region.getRegion(Regions.US_EAST_1); dynamoDB.setRegion(usEast1); } public void createTable(String tableName) { init(); this.tableName = tableName; // Create table if it does not exist yet if (!Tables.doesTableExist(dynamoDB, tableName)) { // Create a table with a primary hash key named 'taskId', which holds a string CreateTableRequest createTableRequest = new CreateTableRequest().withTableName(tableName) .withKeySchema(new KeySchemaElement().withAttributeName("taskId").withKeyType(KeyType.HASH)) .withAttributeDefinitions(new AttributeDefinition().withAttributeName("taskId") .withAttributeType(ScalarAttributeType.S)) .withProvisionedThroughput( new ProvisionedThroughput().withReadCapacityUnits(1L).withWriteCapacityUnits(1L)); TableDescription createdTableDescription = dynamoDB.createTable(createTableRequest) .getTableDescription(); System.out.println("Created Table: " + createdTableDescription); // Wait for it to become active System.out.println("Waiting for " + tableName + " to become ACTIVE..."); try { Tables.awaitTableToBecomeActive(dynamoDB, tableName); } catch (InterruptedException e) { System.out.println("Interrupted Exception"); } // Describe our new table DescribeTableRequest describeTableRequest = new DescribeTableRequest().withTableName(tableName); @SuppressWarnings("unused") TableDescription tableDescription = dynamoDB.describeTable(describeTableRequest).getTable(); } } public boolean isTableExists(String tableName) { if (!Tables.doesTableExist(dynamoDB, tableName)) { return false; } return true; } /*public static void main(String[] args) throws Exception { init(); try { String tableName = "my-favorite-movies-table"; // Create table if it does not exist yet if (Tables.doesTableExist(dynamoDB, tableName)) { System.out.println("Table " + tableName + " is already ACTIVE"); } else { // Create a table with a primary hash key named 'name', which holds a string CreateTableRequest createTableRequest = new CreateTableRequest().withTableName(tableName) .withKeySchema(new KeySchemaElement().withAttributeName("name").withKeyType(KeyType.HASH)) .withAttributeDefinitions(new AttributeDefinition().withAttributeName("name").withAttributeType(ScalarAttributeType.S)) .withProvisionedThroughput(new ProvisionedThroughput().withReadCapacityUnits(1L).withWriteCapacityUnits(1L)); TableDescription createdTableDescription = dynamoDB.createTable(createTableRequest).getTableDescription(); System.out.println("Created Table: " + createdTableDescription); // Wait for it to become active System.out.println("Waiting for " + tableName + " to become ACTIVE..."); Tables.awaitTableToBecomeActive(dynamoDB, 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()); } }*/ /* public static void main(String[] args) { Dynamodb dynamodb = new Dynamodb(); dynamodb.init(); dynamodb.createTable(args[0]); dynamodb.addItemInTable("0", "worker1"); System.out.println(dynamodb.isTaskIdAlreadyPresent("0")); }*/ public synchronized boolean isTaskIdAlreadyPresent(String taskId) { // 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.EQ.toString()) .withAttributeValueList(new AttributeValue().withS(taskId)); scanFilter.put("taskId", condition); ScanRequest scanRequest = new ScanRequest(tableName).withScanFilter(scanFilter); ScanResult scanResult = dynamoDB.scan(scanRequest); if (scanResult.getItems().isEmpty()) { return false; } else { return true; } } public synchronized PutItemResult addItemInTable(String taskId, String workerName) { Map<String, AttributeValue> item = newItem(taskId, workerName); PutItemRequest putItemRequest = new PutItemRequest(tableName, item); PutItemResult putItemResult = dynamoDB.putItem(putItemRequest); return putItemResult; } private static Map<String, AttributeValue> newItem(String taskId, String workerName) { Map<String, AttributeValue> item = new HashMap<String, AttributeValue>(); item.put("taskId", new AttributeValue(taskId)); item.put("workerName", new AttributeValue(workerName)); return item; } }