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我创建了一个 java 服务来从 dynamodb 获取详细信息，它工作正常，但我的挑战是我将表名硬编码到类文件@DynamoDbTable注释中，以便与不同的环境一起工作，我觉得这不是正确的方法。我在下面给出了我的代码，有人可以帮我解决这个问题。

代码示例

public class DynamodbService {

    private DynamoDB client;
    private DynamoDBMapper objectMapper;

    /**
     * 
     * @param client
     * @param objectMapper
     */
    @Autowired
    public DynamodbService(DynamoDB client, DynamoDBMapper objectMapper) {
        this.client = client;
        this.objectMapper = objectMapper;
    }


    public List<Dynamodb> findAll() throws Exception {
        DynamoDBMapperConfig mapperConfig = new DynamoDBMapperConfig.Builder()
                .withTableNameOverride(DynamoDBMapperConfig.TableNameOverride.withTableNameReplacement(""))
                .build();
        DynamoDBMapper mapper = new DynamoDBMapper(client, mapperConfig);

        DynamoDBScanExpression scanExpression = new DynamoDBScanExpression();

        List<Dynamodb> scanResult = objectMapper.scan(Dynamodb.class, scanExpression);
        return scanResult;
    }

}

我的 DynamoDB 配置

@Configuration
public class DynamoDBconfig {
    /**
     * 
     */
    @Value("${amazon.dynamodb.accesskey}")
    private String awsAccessKey;
    /**
     * 
     */
    @Value("${amazon.dynamodb.secretkey}")
    private String awsSecretKey;

    
    @Bean
    public AWSCredentials amazonAWSCredentials() {
        return new BasicAWSCredentials(aes.getDecryptedvalue(awsAccessKey), aes.getDecryptedvalue(awsSecretKey));
    }

    /**
     * 
     * @return
     */
    @Bean
    public DynamoDBMapperConfig dynamoDBMapperConfig() {
        return DynamoDBMapperConfig.DEFAULT;
    }

    /**
     * 
     * @param amazonDynamoDB
     * @param config
     * @return
     */
    @Bean
    public DynamoDBMapper dynamoDBMapper(AmazonDynamoDB amazonDynamoDB, DynamoDBMapperConfig config) {
        return new DynamoDBMapper(amazonDynamoDB, config);
    }

    /**
     * 
     * @return
     */
    @Bean
    public AmazonDynamoDB amazonDynamoDB() {
        return AmazonDynamoDBClientBuilder.standard().withCredentials(amazonAWSCredentialsProvider())
                .withRegion(Regions.US_EAST_2).build();
    }

    /**
     * 
     * @return
     */
    @Bean
    public DynamoDB dynamoDB() {
        return new DynamoDB(amazonDynamoDB());
    }

    /**
     * 
     * @return
     */
    public AWSCredentialsProvider amazonAWSCredentialsProvider() {
        return new AWSStaticCredentialsProvider(amazonAWSCredentials());
    }

}

我的 dynamodb 服务中的错误

构造函数 DynamoDBMapper(DynamoDB, DynamoDBMapperConfig) 未定义

我无法找出问题所在。如果我在类文件中使用表名，如果我尝试使用代码替换表名，它会正常工作，但最终会出错。

4

1 回答 1

3

DynamoDBMapper期望 AmazonDynamoDB 的任何实现，但不是 DynamoDB 类。

public DynamoDBMapper(
            final AmazonDynamoDB dynamoDB,
            final DynamoDBMapperConfig config) {

您只需在服务中注入 DynamoDBMapper。

@Bean
public DynamoDBMapper dynamoDBMapper(AmazonDynamoDB amazonDynamoDB) {
  DynamoDBMapperConfig config = new DynamoDBMapperConfig.Builder().withTableNameOverride(TableNameOverride.withTableNameReplacement(tableName))
        .build();
   return new DynamoDBMapper(amazonDynamoDB, config);
}

其他选项可能是使用 com.amazonaws.services.dynamodbv2.document.DynamoDB类，但你不能使用DynamoDBScanExpression，你需要重写你的代码。


String desiredTabledName = "table-name";
Table table = dynamoDB.getTable(desiredTabledName);


You have multiple options.

 - table.scan() and table query.
 - Index index = table.getIndex(indexName);
   index.scan() or index.query()
 - You could pass `QuerySpec` and `ScanSpec` to all above.
于 2020-08-17T17:53:06.173 回答