示例：使用 Java 文档 API 的本地二级索引 - Amazon DynamoDB

示例：使用 Java 文档 API 的本地二级索引

以下 Java 代码示例显示如何在Amazon DynamoDB 中处理本地二级索引。示例创建名为 CustomerOrders 的表，其分区键为 CustomerId，排序键为 OrderId。此表上有两个本地二级索引：

  • OrderCreationDateIndex — 排序键是 OrderCreationDate，并将以下属性投影到索引：

    • ProductCategory

    • ProductName

    • OrderStatus

    • ShipmentTrackingId

  • IsOpenIndex — 排序键是 IsOpen，并将表的所有属性投影到索引。

创建 CustomerOrders 表后，程序为该表加载表示客户订单的数据。然后使用本地二级索引查询这些数据。最后，程序会删除 CustomerOrders 表。

有关测试以下示例的分步说明，请参阅 Java 代码示例。

例 

package com.example.dynamodb;

import software.amazon.awssdk.core.waiters.WaiterResponse;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.*;
import software.amazon.awssdk.services.dynamodb.waiters.DynamoDbWaiter;

import java.util.HashMap;
import java.util.Map;

public class DocumentAPILocalSecondaryIndexExample {

    static DynamoDbClient client = DynamoDbClient.create();
    public static String tableName = "CustomerOrders";

    public static void main(String[] args) {
        createTable();
        loadData();
        query(null);
        query("IsOpenIndex");
        query("OrderCreationDateIndex");
        deleteTable(tableName);
    }

    public static void createTable() {
        CreateTableRequest request = CreateTableRequest.builder()
            .tableName(tableName)
            .provisionedThroughput(ProvisionedThroughput.builder()
                .readCapacityUnits(1L)
                .writeCapacityUnits(1L)
                .build())
            .attributeDefinitions(
                AttributeDefinition.builder().attributeName("CustomerId").attributeType(ScalarAttributeType.S).build(),
                AttributeDefinition.builder().attributeName("OrderId").attributeType(ScalarAttributeType.N).build(),
                AttributeDefinition.builder().attributeName("OrderCreationDate").attributeType(ScalarAttributeType.N).build(),
                AttributeDefinition.builder().attributeName("IsOpen").attributeType(ScalarAttributeType.N).build())
            .keySchema(
                KeySchemaElement.builder().attributeName("CustomerId").keyType(KeyType.HASH).build(),
                KeySchemaElement.builder().attributeName("OrderId").keyType(KeyType.RANGE).build())
            .localSecondaryIndexes(
                LocalSecondaryIndex.builder()
                    .indexName("OrderCreationDateIndex")
                    .keySchema(
                        KeySchemaElement.builder().attributeName("CustomerId").keyType(KeyType.HASH).build(),
                        KeySchemaElement.builder().attributeName("OrderCreationDate").keyType(KeyType.RANGE).build())
                    .projection(Projection.builder()
                        .projectionType(ProjectionType.INCLUDE)
                        .nonKeyAttributes("ProductCategory", "ProductName")
                        .build())
                    .build(),
                LocalSecondaryIndex.builder()
                    .indexName("IsOpenIndex")
                    .keySchema(
                        KeySchemaElement.builder().attributeName("CustomerId").keyType(KeyType.HASH).build(),
                        KeySchemaElement.builder().attributeName("IsOpen").keyType(KeyType.RANGE).build())
                    .projection(Projection.builder()
                        .projectionType(ProjectionType.ALL)
                        .build())
                    .build())
            .build();

        System.out.println("Creating table " + tableName + "...");
        client.createTable(request);

        try (DynamoDbWaiter waiter = client.waiter()) {
            WaiterResponse<DescribeTableResponse> response = waiter.waitUntilTableExists(r -> r.tableName(tableName));
            response.matched().response().ifPresent(System.out::println);
        }
    }

    public static void query(String indexName) {
        System.out.println("\n***********************************************************\n");
        System.out.println("Querying table " + tableName + "...");

        if ("IsOpenIndex".equals(indexName)) {
            System.out.println("\nUsing index: '" + indexName + "': Bob's orders that are open.");
            System.out.println("Only a user-specified list of attributes are returned\n");

            Map<String, AttributeValue> values = new HashMap<>();
            values.put(":v_custid", AttributeValue.builder().s("bob@example.com").build());
            values.put(":v_isopen", AttributeValue.builder().n("1").build());

            QueryRequest request = QueryRequest.builder()
                .tableName(tableName)
                .indexName(indexName)
                .keyConditionExpression("CustomerId = :v_custid and IsOpen = :v_isopen")
                .expressionAttributeValues(values)
                .projectionExpression("OrderCreationDate, ProductCategory, ProductName, OrderStatus")
                .build();

            System.out.println("Query: printing results...");
            client.query(request).items().forEach(System.out::println);

        } else if ("OrderCreationDateIndex".equals(indexName)) {
            System.out.println("\nUsing index: '" + indexName + "': Bob's orders that were placed after 01/31/2015.");
            System.out.println("Only the projected attributes are returned\n");

            Map<String, AttributeValue> values = new HashMap<>();
            values.put(":v_custid", AttributeValue.builder().s("bob@example.com").build());
            values.put(":v_orddate", AttributeValue.builder().n("20150131").build());

            QueryRequest request = QueryRequest.builder()
                .tableName(tableName)
                .indexName(indexName)
                .keyConditionExpression("CustomerId = :v_custid and OrderCreationDate >= :v_orddate")
                .expressionAttributeValues(values)
                .select(Select.ALL_PROJECTED_ATTRIBUTES)
                .build();

            System.out.println("Query: printing results...");
            client.query(request).items().forEach(System.out::println);

        } else {
            System.out.println("\nNo index: All of Bob's orders, by OrderId:\n");

            Map<String, AttributeValue> values = new HashMap<>();
            values.put(":v_custid", AttributeValue.builder().s("bob@example.com").build());

            QueryRequest request = QueryRequest.builder()
                .tableName(tableName)
                .keyConditionExpression("CustomerId = :v_custid")
                .expressionAttributeValues(values)
                .build();

            System.out.println("Query: printing results...");
            client.query(request).items().forEach(System.out::println);
        }
    }

    public static void deleteTable(String tableName) {
        System.out.println("Deleting table " + tableName + "...");
        client.deleteTable(DeleteTableRequest.builder().tableName(tableName).build());

        try (DynamoDbWaiter waiter = client.waiter()) {
            waiter.waitUntilTableNotExists(r -> r.tableName(tableName));
        }
    }

    public static void loadData() {
        System.out.println("Loading data into table " + tableName + "...");

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("alice@example.com").build(),
            "OrderId", AttributeValue.builder().n("1").build(),
            "IsOpen", AttributeValue.builder().n("1").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150101").build(),
            "ProductCategory", AttributeValue.builder().s("Book").build(),
            "ProductName", AttributeValue.builder().s("The Great Outdoors").build(),
            "OrderStatus", AttributeValue.builder().s("PACKING ITEMS").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("alice@example.com").build(),
            "OrderId", AttributeValue.builder().n("2").build(),
            "IsOpen", AttributeValue.builder().n("1").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150221").build(),
            "ProductCategory", AttributeValue.builder().s("Bike").build(),
            "ProductName", AttributeValue.builder().s("Super Mountain").build(),
            "OrderStatus", AttributeValue.builder().s("ORDER RECEIVED").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("alice@example.com").build(),
            "OrderId", AttributeValue.builder().n("3").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150304").build(),
            "ProductCategory", AttributeValue.builder().s("Music").build(),
            "ProductName", AttributeValue.builder().s("A Quiet Interlude").build(),
            "OrderStatus", AttributeValue.builder().s("IN TRANSIT").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("176493").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("1").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150111").build(),
            "ProductCategory", AttributeValue.builder().s("Movie").build(),
            "ProductName", AttributeValue.builder().s("Calm Before The Storm").build(),
            "OrderStatus", AttributeValue.builder().s("SHIPPING DELAY").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("859323").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("2").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150124").build(),
            "ProductCategory", AttributeValue.builder().s("Music").build(),
            "ProductName", AttributeValue.builder().s("E-Z Listening").build(),
            "OrderStatus", AttributeValue.builder().s("DELIVERED").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("756943").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("3").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150221").build(),
            "ProductCategory", AttributeValue.builder().s("Music").build(),
            "ProductName", AttributeValue.builder().s("Symphony 9").build(),
            "OrderStatus", AttributeValue.builder().s("DELIVERED").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("645193").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("4").build(),
            "IsOpen", AttributeValue.builder().n("1").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150222").build(),
            "ProductCategory", AttributeValue.builder().s("Hardware").build(),
            "ProductName", AttributeValue.builder().s("Extra Heavy Hammer").build(),
            "OrderStatus", AttributeValue.builder().s("PACKING ITEMS").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("5").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150309").build(),
            "ProductCategory", AttributeValue.builder().s("Book").build(),
            "ProductName", AttributeValue.builder().s("How To Cook").build(),
            "OrderStatus", AttributeValue.builder().s("IN TRANSIT").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("440185").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("6").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150318").build(),
            "ProductCategory", AttributeValue.builder().s("Luggage").build(),
            "ProductName", AttributeValue.builder().s("Really Big Suitcase").build(),
            "OrderStatus", AttributeValue.builder().s("DELIVERED").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("893927").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("7").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150324").build(),
            "ProductCategory", AttributeValue.builder().s("Golf").build(),
            "ProductName", AttributeValue.builder().s("PGA Pro II").build(),
            "OrderStatus", AttributeValue.builder().s("OUT FOR DELIVERY").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("383283").build()));
    }

    private static void putItem(Map<String, AttributeValue> item) {
        client.putItem(PutItemRequest.builder().tableName(tableName).item(item).build());
    }
}