使用在 Amazon S3 Glacier 中下载文件库清单Amazon SDK for .NET

以下是使用Amazon SDK for .NET低级 API 检索文件库清单的步骤。该高级 API 不支持取回文件库库存。

创建 AmazonGlacierClient 类（客户端）的实例。

你需要指定Amazon文件库所在的区域。您使用此客户端执行的所有操作都会应用到此Amazon区域。

通过执行 InitiateJob 方法启动清单取回任务。

您可以在中提供任务信息InitiateJobRequest对象。Amazon S3 Glacier (S3 Glacier) 将在响应中返回任务 ID。该响应位于一个 InitiateJobResponse 类的实例中。


AmazonGlacierClient client;
client = new AmazonGlacierClient(Amazon.RegionEndpoint.USWest2);

InitiateJobRequest initJobRequest = new InitiateJobRequest()
{
  VaultName = vaultName,
  JobParameters = new JobParameters()
  {
    Type = "inventory-retrieval",
    SNSTopic = "*** Provide Amazon SNS topic arn ***",
  }
};
InitiateJobResponse initJobResponse = client.InitiateJob(initJobRequest);
string jobId = initJobResponse.JobId;

等待任务完成。

您必须等到任务输出已作好供您下载的准备。如果您在文件库中设置了标识 Amazon Simple Notification Service (Amazon SNS) 主题的通知配置，或者在启动作业时指定了 Amazon SNS 主题，则会在完成作业后向该主题发送消息。以下部分给出的示例使用适用于 S3 Glacier 的 Amazon SNS 来发布消息。

你也可以通过调用调用 S3 GlacierDescribeJob方法来确定作业完成状态。尽管如此，使用 Amazon SNS 主题进行通知才是推荐的方法。
通过执行 GetJobOutput 方法下载任务输出（文件库清单数据）。

您可以通过创建一个 GetJobOutputRequest 类的实例来提供您的账户 ID、文件库名称和任务 ID 信息。如果您不提供账户 ID，则系统会使用与您提供来对请求签名的证书相关联的账户 ID。有关更多信息，请参阅使用Amazon SDK for .NET使用 Amazon S3 Glacier。

S3 Glacier 返回的输出位于GetJobOutputResponse对象。
```
GetJobOutputRequest getJobOutputRequest = new GetJobOutputRequest()
{
  JobId = jobId,
  VaultName = vaultName
};
						       
GetJobOutputResponse getJobOutputResponse = client.GetJobOutput(getJobOutputRequest); 
using (Stream webStream = getJobOutputResponse.Body)
{
   using (Stream fileToSave = File.OpenWrite(fileName))
   {
     CopyStream(webStream, fileToSave);
   }
}
```
注意
有关任务相关的底层 REST API 的信息，请参阅任务操作。

例如：使用低级 API 检索文件库清单Amazon SDK for .NET

以下 C# 代码示例会取回指定文件库的文件库清单。

该示例执行以下任务：

设置 Amazon SNS 主题。

完成作业后，S3 Glacier 会向此主题发送通知。
设置 Amazon SQS 队列。

该示例会向该队列附加策略，以使 Amazon SNS 主题能够发布消息。
启动任务以下载指定的档案。

在作业请求中，该示例会指定 Amazon SNS 主题，以便 S3 Glacier 能够在完成作业后发送消息。
定期检查 Amazon SQS 队列是否有消息。

如果有消息，则分析 JSON，并检查任务是否已成功完成。如果已成功完成，则下载档案。该代码示例使用 JSON.NET 库（请参阅 JSON.NET）来分析 JSON。
通过删除它创建的 Amazon SNS 主题和 Amazon SQS 队列清除相关数据。


using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;
using Amazon.Glacier;
using Amazon.Glacier.Model;
using Amazon.Glacier.Transfer;
using Amazon.Runtime;
using Amazon.SimpleNotificationService;
using Amazon.SimpleNotificationService.Model;
using Amazon.SQS;
using Amazon.SQS.Model;
using Newtonsoft.Json;

namespace glacier.amazon.com.docsamples
{
  class VaultInventoryJobLowLevelUsingSNSSQS
  {
    static string topicArn;
    static string queueUrl;
    static string queueArn;
    static string vaultName = "*** Provide vault name ***";
    static string fileName  = "*** Provide file name and path where to store inventory ***";
    static AmazonSimpleNotificationServiceClient snsClient;
    static AmazonSQSClient sqsClient;
    const string SQS_POLICY =
        "{" +
        "    \"Version\" : \"2012-10-17\"," +
        "    \"Statement\" : [" +
        "        {" +
        "            \"Sid\" : \"sns-rule\"," +
        "            \"Effect\" : \"Allow\"," +
        "            \"Principal\" : {\"AWS\" : \"arn:aws:iam::123456789012:root\" }," +
        "            \"Action\"    : \"sqs:SendMessage\"," +
        "            \"Resource\"  : \"{QuernArn}\"," +
        "            \"Condition\" : {" +
        "                \"ArnLike\" : {" +
        "                    \"aws:SourceArn\" : \"{TopicArn}\"" +
        "                }" +
        "            }" +
        "        }" +
        "    ]" +
        "}";

    public static void Main(string[] args)
    {
      AmazonGlacierClient client;
      try
      {
        using (client = new AmazonGlacierClient(Amazon.RegionEndpoint.USWest2))
        {
            Console.WriteLine("Setup SNS topic and SQS queue."); 
            SetupTopicAndQueue();
            Console.WriteLine("To continue, press Enter"); Console.ReadKey();
            
            Console.WriteLine("Retrieve Inventory List");
            GetVaultInventory(client);
        }
        Console.WriteLine("Operations successful.");
        Console.WriteLine("To continue, press Enter"); Console.ReadKey();
      }
      catch (AmazonGlacierException e) { Console.WriteLine(e.Message); }
      catch (AmazonServiceException e) { Console.WriteLine(e.Message); }
      catch (Exception e) { Console.WriteLine(e.Message); }
      finally
      {        
       // Delete SNS topic and SQS queue.
       snsClient.DeleteTopic(new DeleteTopicRequest() { TopicArn = topicArn });
       sqsClient.DeleteQueue(new DeleteQueueRequest() { QueueUrl = queueUrl });
      }
    }

    static void SetupTopicAndQueue()
    {
      long ticks = DateTime.Now.Ticks;
      
      // Setup SNS topic.
      snsClient = new AmazonSimpleNotificationServiceClient(Amazon.RegionEndpoint.USWest2);
      sqsClient = new AmazonSQSClient(Amazon.RegionEndpoint.USWest2);

      topicArn = snsClient.CreateTopic(new CreateTopicRequest { Name = "GlacierDownload-" + ticks }).TopicArn;
      Console.Write("topicArn: "); Console.WriteLine(topicArn);
 
      CreateQueueRequest createQueueRequest =  new CreateQueueRequest();
      createQueueRequest.QueueName = "GlacierDownload-" + ticks;
      CreateQueueResponse createQueueResponse = sqsClient.CreateQueue(createQueueRequest);
      queueUrl = createQueueResponse.QueueUrl;
      Console.Write("QueueURL: "); Console.WriteLine(queueUrl);

      GetQueueAttributesRequest getQueueAttributesRequest = new GetQueueAttributesRequest();
      getQueueAttributesRequest.AttributeNames = new List<string> { "QueueArn" };
      getQueueAttributesRequest.QueueUrl = queueUrl;
      GetQueueAttributesResponse response = sqsClient.GetQueueAttributes(getQueueAttributesRequest);
      queueArn = response.QueueARN;
      Console.Write("QueueArn: ");Console.WriteLine(queueArn);

      // Setup the Amazon SNS topic to publish to the SQS queue.
      snsClient.Subscribe(new SubscribeRequest()
      {
        Protocol = "sqs",
        Endpoint = queueArn,
        TopicArn = topicArn
      });

      // Add the policy to the queue so SNS can send messages to the queue.
      var policy = SQS_POLICY.Replace("{TopicArn}", topicArn).Replace("{QuernArn}", queueArn);
     
      sqsClient.SetQueueAttributes(new SetQueueAttributesRequest()
      {
          QueueUrl = queueUrl,
          Attributes = new Dictionary<string, string>
          {
              { QueueAttributeName.Policy, policy }
          }
      });

    }
 
    static void GetVaultInventory(AmazonGlacierClient client)
    {
      // Initiate job.
      InitiateJobRequest initJobRequest = new InitiateJobRequest()
      {
        VaultName = vaultName,
        JobParameters = new JobParameters()
        {
          Type = "inventory-retrieval",
          Description = "This job is to download a vault inventory.",
          SNSTopic = topicArn,
        }
      };
   
      InitiateJobResponse initJobResponse = client.InitiateJob(initJobRequest);
      string jobId = initJobResponse.JobId;

      // Check queue for a message and if job completed successfully, download inventory.
      ProcessQueue(jobId, client);    
    }

    private static void ProcessQueue(string jobId, AmazonGlacierClient client)
    {
      ReceiveMessageRequest receiveMessageRequest = new ReceiveMessageRequest() { QueueUrl = queueUrl, MaxNumberOfMessages = 1 };
      bool jobDone = false;
      while (!jobDone)
      {
        Console.WriteLine("Poll SQS queue"); 
        ReceiveMessageResponse receiveMessageResponse = sqsClient.ReceiveMessage(receiveMessageRequest);
        if (receiveMessageResponse.Messages.Count == 0)
        {
          Thread.Sleep(10000 * 60);
          continue;
        }
        Console.WriteLine("Got message");
        Message message = receiveMessageResponse.Messages[0];
        Dictionary<string, string> outerLayer = JsonConvert.DeserializeObject<Dictionary<string, string>>(message.Body);
        Dictionary<string, object> fields = JsonConvert.DeserializeObject<Dictionary<string, object>>(outerLayer["Message"]);
        string statusCode = fields["StatusCode"] as string;

        if (string.Equals(statusCode, GlacierUtils.JOB_STATUS_SUCCEEDED, StringComparison.InvariantCultureIgnoreCase))
        {
          Console.WriteLine("Downloading job output");
          DownloadOutput(jobId, client); // Save job output to the specified file location.
        }
        else if (string.Equals(statusCode, GlacierUtils.JOB_STATUS_FAILED, StringComparison.InvariantCultureIgnoreCase))
          Console.WriteLine("Job failed... cannot download the inventory.");

        jobDone = true;
        sqsClient.DeleteMessage(new DeleteMessageRequest() { QueueUrl = queueUrl, ReceiptHandle = message.ReceiptHandle });
      }
    }

    private static void DownloadOutput(string jobId, AmazonGlacierClient client)
    {
      GetJobOutputRequest getJobOutputRequest = new GetJobOutputRequest()
      {      
        JobId = jobId,
        VaultName = vaultName
      };
      
      GetJobOutputResponse getJobOutputResponse = client.GetJobOutput(getJobOutputRequest); 
      using (Stream webStream = getJobOutputResponse.Body)
      {
        using (Stream fileToSave = File.OpenWrite(fileName))
        {
          CopyStream(webStream, fileToSave);
        }
      }
    }

    public static void CopyStream(Stream input, Stream output)
    {
      byte[] buffer = new byte[65536];
      int length;
      while ((length = input.Read(buffer, 0, buffer.Length)) > 0)
      {
        output.Write(buffer, 0, length);
      }
    }
  }
}

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