本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。 # 等待程式從第 1 版變更為第 2 版本主題詳細說明等待程式功能從第 1 版 (v1) 到第 2 版 (v2) 的變更。下表特別示範 DynamoDB 等待程式的差異。其他服務的等待程式遵循相同的模式。 ## 高階變更等待程式類別與服務位於相同的 Maven 成品。 | 變更 | v1 | v2 | | --- | --- | --- | | Maven 相依性 |


    
        
            com.amazonaws
            aws-java-sdk-bom
            1.12.6801
            pom
            import
        
    


    
        com.amazonaws
        dynamodb


    
        
            software.amazon.awssdk
            bom
            2.27.102
            pom
            import
        
    


    
        software.amazon.awssdk
        dynamodb

| | 套件名稱 | com.amazonaws.services.dynamodbv2.waiters | software.amazon.awssdk.services.dynamodb.waiters | | 類別名稱 | `[AmazonDynamoDBWaiters](https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/services/dynamodbv2/waiters/AmazonDynamoDBWaiters.html)` | [\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/zh_tw/sdk-for-java/latest/developer-guide/migration-waiters.html) | 1 [最新版本](https://central.sonatype.com/artifact/com.amazonaws/aws-java-sdk-bom)。 2 [最新版本](https://central.sonatype.com/artifact/software.amazon.awssdk/bom)。 ## API 變更 | 變更 | v1 | v2 | | --- | --- | --- | | 建立等待程式 |

AmazonDynamoDB client = AmazonDynamoDBClientBuilder 
                            .standard().build();
AmazonDynamoDBWaiters waiter = client.waiters();

| 同步：

DynamoDbClient client = DynamoDbClient.create();
DynamoDbWaiter waiter = client.waiter();

非同步：

DynamoDbAsyncClient asyncClient = 
        DynamoDbAsyncClient.create();
DynamoDbAsyncWaiter waiter = asyncClient.waiter();

| | 等到資料表存在 | 同步：

waiter.tableExists()
    .run(new WaiterParameters<>(
        new DescribeTableRequest(tableName)));

非同步：

waiter.tableExists()
    .runAsync(new WaiterParameters()
      .withRequest(new DescribeTableRequest(tableName)),
          new WaiterHandler() {
              @Override
              public void onWaitSuccess(
                  AmazonWebServiceRequest amazonWebServiceRequest) {
                    System.out.println("Table creation succeeded");
              }

              @Override
              public void onWaitFailure(Exception e) {
                  e.printStackTrace();
              }
          }).get();

| 同步：

WaiterResponse waiterResponse =
    waiter.waitUntilTableExists(
        r -> r.tableName("myTable"));
waiterResponse.matched().response()
       .ifPresent(System.out::println);

非同步：

waiter.waitUntilTableExists(r -> r.tableName(tableName))
           .whenComplete((r, t) -> {
               if (t != null) {
                   t.printStackTrace();
               } else {
                   System.out.println(
                        "Table creation succeeded");
               }
           }).join();

| ## 組態變更 | 變更 | v1 | v2 | | --- | --- | --- | | 輪詢策略（最大嘗試次數和固定延遲） |

MaxAttemptsRetryStrategy maxAttemptsRetryStrategy = 
        new MaxAttemptsRetryStrategy(10);

FixedDelayStrategy fixedDelayStrategy = 
        new FixedDelayStrategy(3);

PollingStrategy pollingStrategy = 
        new PollingStrategy(maxAttemptsRetryStrategy, 
                fixedDelayStrategy);

waiter.tableExists().run(
        new WaiterParameters<>(
            new DescribeTableRequest(tableName)), 
                pollingStrategy);


FixedDelayBackoffStrategy fixedDelayBackoffStrategy = 
        FixedDelayBackoffStrategy
            .create(Duration.ofSeconds(3));

waiter.waitUntilTableExists(r -> r.tableName(tableName),
        c -> c.maxAttempts(10)
                .backoffStrategy(fixedDelayBackoffStrategy));