Menanyakan indeks sekunder global dengan SDK untuk Java 1.x

Anda dapat menggunakan Amazon DynamoDB Accelerator DAX () untuk menanyakan indeks sekunder global menggunakan antarmuka terprogram DynamoDB.

Contoh berikut menunjukkan bagaimana menggunakan DAX untuk query indeks sekunder CreateDateIndex global yang dibuat dalam Contoh: Indeks sekunder global menggunakan dokumen. AWS SDK for Java API

Kelas DAXClient membuat instans objek klien yang diperlukan untuk berinteraksi dengan antarmuka pemrograman DynamoDB.

import com.amazon.dax.client.dynamodbv2.AmazonDaxClientBuilder;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper;
import com.amazonaws.services.dynamodbv2.document.DynamoDB;
import com.amazonaws.util.EC2MetadataUtils;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;

public class DaxClient {

	private static final String region = EC2MetadataUtils.getEC2InstanceRegion();

	DynamoDB getDaxDocClient(String daxEndpoint) {
		System.out.println("Creating a DAX client with cluster endpoint " + daxEndpoint);
		AmazonDaxClientBuilder daxClientBuilder = AmazonDaxClientBuilder.standard();

		daxClientBuilder.withRegion(region).withEndpointConfiguration(daxEndpoint);
		AmazonDynamoDB client = daxClientBuilder.build();

		return new DynamoDB(client);
	}

	DynamoDBMapper getDaxMapperClient(String daxEndpoint) {
		System.out.println("Creating a DAX client with cluster endpoint " + daxEndpoint);
		AmazonDaxClientBuilder daxClientBuilder = AmazonDaxClientBuilder.standard();

		daxClientBuilder.withRegion(region).withEndpointConfiguration(daxEndpoint);
		AmazonDynamoDB client = daxClientBuilder.build();

		return new DynamoDBMapper(client);
	}
}

Anda dapat mengkueri indeks sekunder global dengan cara berikut:

import java.util.Iterator;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper;
import java.util.List;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBQueryExpression;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;
import java.util.HashMap;
import com.amazonaws.services.dynamodbv2.document.Item;
import com.amazonaws.services.dynamodbv2.document.utils.ValueMap;
import com.amazonaws.services.dynamodbv2.document.spec.QuerySpec;
import com.amazonaws.services.dynamodbv2.document.QueryOutcome;
import com.amazonaws.services.dynamodbv2.document.ItemCollection;
import com.amazonaws.services.dynamodbv2.document.Index;
import com.amazonaws.services.dynamodbv2.document.Table;
import com.amazonaws.services.dynamodbv2.document.DynamoDB;

public class QueryIndexDax {

	//This is used to query Index using the low-level interface.
	public static void queryIndex(DynamoDB client, String tableName, String indexName) {
		Table table = client.getTable(tableName);

		System.out.println("\n***********************************************************\n");
		System.out.print("Querying index " + indexName + "...");

		Index index = table.getIndex(indexName);

		ItemCollection<QueryOutcome> items = null;

		QuerySpec querySpec = new QuerySpec();

		if (indexName == "CreateDateIndex") {
			System.out.println("Issues filed on 2013-11-01");
			querySpec.withKeyConditionExpression("CreateDate = :v_date and begins_with(IssueId, :v_issue)")
					.withValueMap(new ValueMap().withString(":v_date", "2013-11-01").withString(":v_issue", "A-"));
			items = index.query(querySpec);
		} else {
			System.out.println("\nNo valid index name provided");
			return;
		}

		Iterator<Item> iterator = items.iterator();

		System.out.println("Query: printing results...");

		while (iterator.hasNext()) {
			System.out.println(iterator.next().toJSONPretty());
		}

	}

	//This is used to query Index using the high-level mapper interface.
	public static void queryIndexMapper(DynamoDBMapper mapper, String tableName, String indexName) {
		HashMap<String, AttributeValue> eav = new HashMap<String, AttributeValue>();
		eav.put(":v_date", new AttributeValue().withS("2013-11-01"));
		eav.put(":v_issue", new AttributeValue().withS("A-"));
		DynamoDBQueryExpression<CreateDate> queryExpression = new DynamoDBQueryExpression<CreateDate>()
				.withIndexName("CreateDateIndex").withConsistentRead(false)
				.withKeyConditionExpression("CreateDate = :v_date and begins_with(IssueId, :v_issue)")
				.withExpressionAttributeValues(eav);

		List<CreateDate> items = mapper.query(CreateDate.class, queryExpression);
		Iterator<CreateDate> iterator = items.iterator();

		System.out.println("Query: printing results...");

		while (iterator.hasNext()) {
			CreateDate iterObj = iterator.next();
			System.out.println(iterObj.getCreateDate());
			System.out.println(iterObj.getIssueId());
		}
	}
}

Definisi kelas di bawah ini merupakan tabel Masalah dan digunakan dalam metode queryIndexMapper.

import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTable;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBIndexHashKey;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBIndexRangeKey;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBHashKey;

@DynamoDBTable(tableName = "Issues")
public class CreateDate {
	private String createDate;
	@DynamoDBHashKey(attributeName = "IssueId")
	private String issueId;

	@DynamoDBIndexHashKey(globalSecondaryIndexName = "CreateDateIndex", attributeName = "CreateDate")
	public String getCreateDate() {
		return createDate;
	}

	public void setCreateDate(String createDate) {
		this.createDate = createDate;
	}

	@DynamoDBIndexRangeKey(globalSecondaryIndexName = "CreateDateIndex", attributeName = "IssueId")
	public String getIssueId() {
		return issueId;
	}

	public void setIssueId(String issueId) {
		this.issueId = issueId;
	}
}