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本文属于机器翻译版本。若本译文内容与英语原文存在差异，则一律以英文原文为准。
服务员从版本 1 到版本 2 的变化 本主题详细介绍了 Waiters 功能从版本 1 (v1) 到版本 2 (v2) 的变化。
下表具体说明了 DynamoDB 服务员的区别。其他服务的服务员也遵循同样的模式。
高级别更改
服务员的职业与该服务位于同一个 Maven 工件中。
更改
v1
v2
Maven 依赖项
<dependencyManagement >
<dependencies >
<dependency >
<groupId > com.amazonaws</groupId >
<artifactId > aws-java-sdk-bom</artifactId >
<version > 1.12.6801 </version >
<type > pom</type >
<scope > import</scope >
</dependency >
</dependencies >
</dependencyManagement >
<dependencies >
<dependency >
<groupId > com.amazonaws</groupId >
<artifactId > dynamodb</artifactId >
</dependency >
</dependencies >
<dependencyManagement >
<dependencies >
<dependency >
<groupId > software.amazon.awssdk</groupId >
<artifactId > bom</artifactId >
<version > 2.27.102 </version >
<type > pom</type >
<scope > import</scope >
</dependency >
</dependencies >
</dependencyManagement >
<dependencies >
<dependency >
<groupId > software.amazon.awssdk</groupId >
<artifactId > dynamodb</artifactId >
</dependency >
</dependencies >
程序包名称
com.amazonaws.services.dynamodbv2.waiterssoftware.amazon.awssdk.services.dynamodb.waiters
类名
AmazonDynamoDBWaiters
1 最新版本 2 最新版本
API 变更
更改
v1
v2
创建服务员
AmazonDynamoDB client = AmazonDynamoDBClientBuilder
.standard().build();
AmazonDynamoDBWaiters waiter = client.waiters();
同步：DynamoDbClient client = DynamoDbClient.create();
DynamoDbWaiter waiter = client.waiter();异步：
DynamoDbAsyncClient asyncClient =
DynamoDbAsyncClient.create();
DynamoDbAsyncWaiter waiter = asyncClient.waiter();
等到表存在
同步：waiter.tableExists()
.run(new WaiterParameters<>(
new DescribeTableRequest(tableName)));异步：
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<DescribeTableResponse> waiterResponse =
waiter.waitUntilTableExists(
r -> r.tableName("myTable" ));
waiterResponse.matched().response()
.ifPresent(System.out::println);异步：
waiter.waitUntilTableExists(r -> r.tableName(tableName))
.whenComplete((r, t) -> {
if (t != null ) {
t.printStackTrace();
} else {
System.out.println(
"Table creation succeeded" );
}
}).join();
配置更改
更改
v1
v2
轮询策略（最大尝试次数和固定延迟）
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));
