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# `StartLifecyclePolicyPreview`与 AWS SDK 或 CLI 配合使用
<a name="example_ecr_StartLifecyclePolicyPreview_section"></a>

以下代码示例演示如何使用 `StartLifecyclePolicyPreview`。

操作示例是大型程序的代码摘录，必须在上下文中运行。在以下代码示例中，您可以查看此操作的上下文：
+  [了解基本功能](example_ecr_Scenario_RepositoryManagement_section.md) 

------
#### [ CLI ]

**AWS CLI**  
**要创建生命周期策略预览**  
以下 `start-lifecycle-policy-preview` 示例创建了由指定存储库的 JSON 文件定义的生命周期策略预览。  

```
aws ecr start-lifecycle-policy-preview \
    --repository-name "project-a/amazon-ecs-sample" \
    --lifecycle-policy-text "file://policy.json"
```
`policy.json` 的内容：  

```
{
   "rules": [
       {
           "rulePriority": 1,
           "description": "Expire images older than 14 days",
           "selection": {
               "tagStatus": "untagged",
               "countType": "sinceImagePushed",
               "countUnit": "days",
               "countNumber": 14
           },
           "action": {
               "type": "expire"
           }
       }
   ]
}
```
输出：  

```
{
   "registryId": "012345678910",
   "repositoryName": "project-a/amazon-ecs-sample",
   "lifecyclePolicyText": "{\n    \"rules\": [\n        {\n            \"rulePriority\": 1,\n            \"description\": \"Expire images older than 14 days\",\n            \"selection\": {\n                \"tagStatus\": \"untagged\",\n                \"countType\": \"sinceImagePushed\",\n                \"countUnit\": \"days\",\n                \"countNumber\": 14\n            },\n            \"action\": {\n                \"type\": \"expire\"\n            }\n        }\n    ]\n}\n",
   "status": "IN_PROGRESS"
}
```
+  有关 API 的详细信息，请参阅*AWS CLI 命令参考[StartLifecyclePolicyPreview](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ecr/start-lifecycle-policy-preview.html)*中的。

------
#### [ Java ]

**适用于 Java 的 SDK 2.x**  
 还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/ecr#code-examples)中查找完整示例，了解如何进行设置和运行。

```
    /**
     * Verifies the existence of an image in an Amazon Elastic Container Registry (Amazon ECR) repository asynchronously.
     *
     * @param repositoryName The name of the Amazon ECR repository.
     * @param imageTag       The tag of the image to verify.
     * @throws EcrException             if there is an error retrieving the image information from Amazon ECR.
     * @throws CompletionException      if the asynchronous operation completes exceptionally.
     */
    public void verifyImage(String repositoryName, String imageTag) {
        DescribeImagesRequest request = DescribeImagesRequest.builder()
            .repositoryName(repositoryName)
            .imageIds(ImageIdentifier.builder().imageTag(imageTag).build())
            .build();

        CompletableFuture<DescribeImagesResponse> response = getAsyncClient().describeImages(request);
        response.whenComplete((describeImagesResponse, ex) -> {
            if (ex != null) {
                if (ex instanceof CompletionException) {
                    Throwable cause = ex.getCause();
                    if (cause instanceof EcrException) {
                        throw (EcrException) cause;
                    } else {
                        throw new RuntimeException("Unexpected error: " + cause.getMessage(), cause);
                    }
                } else {
                    throw new RuntimeException("Unexpected error: " + ex.getCause());
                }
            } else if (describeImagesResponse != null && !describeImagesResponse.imageDetails().isEmpty()) {
                System.out.println("Image is present in the repository.");
            } else {
                System.out.println("Image is not present in the repository.");
            }
        });

        // Wait for the CompletableFuture to complete.
        response.join();
    }
```
+  有关 API 的详细信息，请参阅 *AWS SDK for Java 2.x API 参考[StartLifecyclePolicyPreview](https://docs.aws.amazon.com/goto/SdkForJavaV2/ecr-2015-09-21/StartLifecyclePolicyPreview)*中的。

------
#### [ Kotlin ]

**适用于 Kotlin 的 SDK**  
 还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/ecr#code-examples)中查找完整示例，了解如何进行设置和运行。

```
    /**
     * Verifies the existence of an image in an Amazon Elastic Container Registry (Amazon ECR) repository asynchronously.
     *
     * @param repositoryName The name of the Amazon ECR repository.
     * @param imageTag       The tag of the image to verify.
     */
    suspend fun verifyImage(
        repoName: String?,
        imageTagVal: String?,
    ) {
        require(!(repoName == null || repoName.isEmpty())) { "Repository name cannot be null or empty" }
        require(!(imageTagVal == null || imageTagVal.isEmpty())) { "Image tag cannot be null or empty" }

        val imageId =
            ImageIdentifier {
                imageTag = imageTagVal
            }
        val request =
            DescribeImagesRequest {
                repositoryName = repoName
                imageIds = listOf(imageId)
            }

        EcrClient.fromEnvironment { region = "us-east-1" }.use { ecrClient ->
            val describeImagesResponse = ecrClient.describeImages(request)
            if (describeImagesResponse != null && !describeImagesResponse.imageDetails?.isEmpty()!!) {
                println("Image is present in the repository.")
            } else {
                println("Image is not present in the repository.")
            }
        }
    }
```
+  有关 API 的详细信息，请参阅适用[StartLifecyclePolicyPreview](https://sdk.amazonaws.com/kotlin/api/latest/index.html)于 K *otlin 的AWS SDK API 参考*。

------

有关 S AWS DK 开发者指南和代码示例的完整列表，请参阅[将 Amazon ECR 与软件开发工具包一起使用 AWS](sdk-general-information-section.md)。本主题还包括有关入门的信息以及有关先前的 SDK 版本的详细信息。