Question

您好我正在尝试创建一个java程序来检查亚马逊dynamodb中存在的值。好吧，实际上我正在尝试为零售商店编写一个java程序，程序检查dynamodb中的某个产品（值）并返回商店中存在的数量。我已经在dynamodb中创建了一个表，并且还使用了扫描api来检索items.But现在我想搜索某个值是否存在，并返回当前数量。如果有人能用一个片段帮助我，那将是非常有帮助的。 ps：我是java的新手

由于

Answer 1

为表ConsumerTable提供以下数据建模，并将leaseKey作为索引字段;

{
  "checkpoint": "49572533067729099438069946639296561054199125138133221378",
  "checkpointSubSequenceNumber": 0,
  "leaseCounter": 1372794,
  "leaseKey": "shardId-000000000000",
  "leaseOwner": "pout_172.21.63.243",
  "ownerSwitchesSinceCheckpoint": 0
}

通过索引字段查询Amazon DynamoDB的Java API将是

import com.amazonaws.ClientConfiguration;

import com.amazonaws.regions.Region;
import com.amazonaws.regions.Regions;
import com.amazonaws.retry.v2.RetryPolicy;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient;
import com.amazonaws.services.dynamodbv2.document.DynamoDB;

public AmazonDynamoDB getDbConnection() {
    AmazonDynamoDBClient dynamoDB = new AmazonDynamoDBClient( new ProfileCredentialsProvider("your-aws-auth-profile_in_~/.aws/credentials"));

    dynamoDB.setRegion(Region.getRegion(Regions.US_WEST_2))

    return dynamoDB;
}

public void getData() {

    DynamoDB dynamoDB = new DynamoDB(getDbConnection());
    Table consumerOffsetTable = dynamoDB.getTable("ConsumerTable");

    Optional.ofNullable(consumerOffsetTable.getItem("leaseKey", "shardId-000000000000")).ifPresent(item -> {

        Map<String, Object> itemMap = item.asMap();

        System.out.println(itemMap.get("leaseKey").toString() + " -> " + itemMap.get("checkpoint").toString());

    });

}

Maven依赖将是

<dependency>
  <groupId>com.amazonaws</groupId>
  <artifactId>aws-java-sdk-dynamodb</artifactId>
  <version>1.11.115</version>
</dependency>

在product，quantity示例中，索引product属性和查询应与上述示例类似。

资源

使用SDK进行AWS访问 - http://docs.aws.amazon.com/sdk-for-java/v1/developer-guide/credentials.html

对于Dynamodb apis

http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ScanJavaDocumentAPI.html

http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/QueryingJavaDocumentAPI.html

如何使用java检查dynamodb中的项目？

1 个答案:

资源