我们可以在同一个项目中同时使用 aws dynamodb 版本 1.x 和 2.x 吗？

Question

The reason I was asking this because aws sdk dynamodb version 2.x doesn't have support for DynamoDB Mappers. So I want to leverage dynamodb mapper from 1.x and automatic pagination and other features from 2.x.

Or Is there any alternative to dynamodb mappers in aws sdk 2.0? Please let me know. thanks

Answer 1

AWS Java SDK for DynamoDB indeed supports DynamoDB Mappers:

See: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBMapper.html

And the GitHub Source: https://github.com/aws/aws-sdk-java/blob/master/aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/datamodeling/DynamoDBMapper.java

You can use DynamoDB Mapper as from the latest SDK as below:

package com.amazonaws.codesamples;

import java.util.Set;

import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBAttribute;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBHashKey;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBIgnore;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTable;

@DynamoDBTable(tableName="ProductCatalog")
public class CatalogItem {

    private Integer id;
    private String title;
    private String ISBN;
    private Set<String> bookAuthors;
    private String someProp;

    @DynamoDBHashKey(attributeName="Id")  
    public Integer getId() { return id; }
    public void setId(Integer id) {this.id = id; }

    @DynamoDBAttribute(attributeName="Title")  
    public String getTitle() {return title; }
    public void setTitle(String title) { this.title = title; }

    @DynamoDBAttribute(attributeName="ISBN")  
    public String getISBN() { return ISBN; }
    public void setISBN(String ISBN) { this.ISBN = ISBN; }

    @DynamoDBAttribute(attributeName="Authors")
    public Set<String> getBookAuthors() { return bookAuthors; }
    public void setBookAuthors(Set<String> bookAuthors) { this.bookAuthors = bookAuthors; }

    @DynamoDBIgnore
    public String getSomeProp() { return someProp; }
    public void setSomeProp(String someProp) { this.someProp = someProp; }
}

And later:

AmazonDynamoDB client = AmazonDynamoDBClientBuilder.standard().build();

DynamoDBMapper mapper = new DynamoDBMapper(client);

CatalogItem item = new CatalogItem();
item.setId(102);
item.setTitle("Book 102 Title");
item.setISBN("222-2222222222");
item.setBookAuthors(new HashSet<String>(Arrays.asList("Author 1", "Author 2")));
item.setSomeProp("Test");

mapper.save(item);         

Answer 2

It actually has the Mapper within version 2. https://sdk.amazonaws.com/java/api/latest/software/amazon/awssdk/enhanced/dynamodb/mapper/annotations/DynamoDbPartitionKey.html

It is in software.amazon.awssdk.enhanced.dynamodb.