適用於 .NET 的 AWS SDK V3 已進入維護模式。

我們建議您遷移至 [適用於 .NET 的 AWS SDK V4](https://docs.aws.amazon.com/sdk-for-net/v4/developer-guide/welcome.html)。如需如何遷移的其他詳細資訊和資訊，請參閱我們的[維護模式公告](https://aws.amazon.com/blogs/developer/aws-sdk-for-net-v3-maintenance-mode-announcement/)。

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。

# 更新 Amazon SQS 佇列
<a name="UpdateSqsQueue"></a>

此範例說明如何使用 適用於 .NET 的 AWS SDK 來更新 Amazon SQS 佇列。經過一些檢查後，應用程式會使用指定的值更新指定的屬性，然後顯示佇列的所有屬性。

如果命令列引數中只包含佇列 URL，則應用程式只會顯示佇列的所有屬性。

下列各節提供此範例的程式碼片段。之後會顯示[範例的完整程式碼](#UpdateSqsQueue-complete-code)，並可依原樣建置和執行。

**Topics**
+ [顯示佇列屬性](#UpdateSqsQueue-show-attributes)
+ [驗證屬性名稱](#UpdateSqsQueue-validate-attribute)
+ [更新佇列屬性](#UpdateSqsQueue-update-attribute)
+ [完成程式碼](#UpdateSqsQueue-complete-code)
+ [其他考量](#UpdateSqsQueue-additional)

## 顯示佇列屬性
<a name="UpdateSqsQueue-show-attributes"></a>

下列程式碼片段顯示指定佇列 URL 所識別之佇列的屬性。

[本主題結尾](#UpdateSqsQueue-complete-code)的範例顯示此程式碼片段正在使用中。

```
    //
    // Method to show all attributes of a queue
    private static async Task ShowAllAttributes(IAmazonSQS sqsClient, string qUrl)
    {
      GetQueueAttributesResponse responseGetAtt =
        await sqsClient.GetQueueAttributesAsync(qUrl,
          new List<string>{ QueueAttributeName.All });
      Console.WriteLine($"Queue: {qUrl}");
      foreach(var att in responseGetAtt.Attributes)
        Console.WriteLine($"\t{att.Key}: {att.Value}");
    }
```

## 驗證屬性名稱
<a name="UpdateSqsQueue-validate-attribute"></a>

下列程式碼片段會驗證要更新的屬性名稱。

[本主題結尾](#UpdateSqsQueue-complete-code)的範例顯示此程式碼片段正在使用中。

```
    //
    // Method to check the name of the attribute
    private static bool ValidAttribute(string attribute)
    {
      var attOk = false;
      var qAttNameType = typeof(QueueAttributeName);
      List<string> qAttNamefields = new List<string>();
      foreach(var field in qAttNameType.GetFields())
       qAttNamefields.Add(field.Name);
      foreach(var name in qAttNamefields)
        if(attribute == name) { attOk = true; break; }
      return attOk;
    }
```

## 更新佇列屬性
<a name="UpdateSqsQueue-update-attribute"></a>

下列程式碼片段會更新指定佇列 URL 所識別之佇列的屬性。

[本主題結尾](#UpdateSqsQueue-complete-code)的範例顯示此程式碼片段正在使用中。

```
    //
    // Method to update a queue attribute
    private static async Task UpdateAttribute(
      IAmazonSQS sqsClient, string qUrl, string attribute, string value)
    {
      await sqsClient.SetQueueAttributesAsync(qUrl,
        new Dictionary<string, string>{{attribute, value}});
    }
```

## 完成程式碼
<a name="UpdateSqsQueue-complete-code"></a>

本節顯示此範例的相關參考和完整程式碼。

### 開發套件參考
<a name="w2aac19c15c25c19c25b5b1"></a>

NuGet 套件：
+ [AWSSDK.SQS](https://www.nuget.org/packages/AWSSDK.SQS)

程式設計元素：
+ 命名空間 [Amazon.SQS](https://docs.aws.amazon.com/sdkfornet/v3/apidocs/items/SQS/NSQS.html)

  [AmazonSQSClient](https://docs.aws.amazon.com/sdkfornet/v3/apidocs/items/SQS/TSQSClient.html) 類別

  類別 [QueueAttributeName](https://docs.aws.amazon.com/sdkfornet/v3/apidocs/items/SQS/TQueueAttributeName.html)
+ 命名空間 [Amazon.SQS.Model](https://docs.aws.amazon.com/sdkfornet/v3/apidocs/items/SQS/NSQSModel.html)

  類別 [GetQueueAttributesResponse](https://docs.aws.amazon.com/sdkfornet/v3/apidocs/items/SQS/TGetQueueAttributesResponse.html)

### 程式碼
<a name="w2aac19c15c25c19c25b7b1"></a>

```
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Amazon.SQS;
using Amazon.SQS.Model;

namespace SQSUpdateQueue
{
  // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  // Class to update a queue
  class Program
  {
    private const int MaxArgs = 3;
    private const int InvalidArgCount = 2;

    static async Task Main(string[] args)
    {
      // Parse the command line and show help if necessary
      var parsedArgs = CommandLine.Parse(args);
      if(parsedArgs.Count == 0)
      {
        PrintHelp();
        return;
      }
      if((parsedArgs.Count > MaxArgs) || (parsedArgs.Count == InvalidArgCount))
        CommandLine.ErrorExit("\nThe number of command-line arguments is incorrect." +
          "\nRun the command with no arguments to see help.");

      // Get the application arguments from the parsed list
      var qUrl = CommandLine.GetArgument(parsedArgs, null, "-q");
      var attribute = CommandLine.GetArgument(parsedArgs, null, "-a");
      var value = CommandLine.GetArgument(parsedArgs, null, "-v", "--value");

      if(string.IsNullOrEmpty(qUrl))
        CommandLine.ErrorExit("\nYou must supply at least a queue URL." +
          "\nRun the command with no arguments to see help.");

      // Create the Amazon SQS client
      var sqsClient = new AmazonSQSClient();

      // In the case of one command-line argument, just show the attributes for the queue
      if(parsedArgs.Count == 1)
        await ShowAllAttributes(sqsClient, qUrl);

      // Otherwise, attempt to update the given queue attribute with the given value
      else
      {
        // Check to see if the attribute is valid
        if(ValidAttribute(attribute))
        {
          // Perform the update and then show all the attributes of the queue
          await UpdateAttribute(sqsClient, qUrl, attribute, value);
          await ShowAllAttributes(sqsClient, qUrl);
        }
        else
        {
          Console.WriteLine($"\nThe given attribute name, {attribute}, isn't valid.");
        }
      }
    }


    //
    // Method to show all attributes of a queue
    private static async Task ShowAllAttributes(IAmazonSQS sqsClient, string qUrl)
    {
      GetQueueAttributesResponse responseGetAtt =
        await sqsClient.GetQueueAttributesAsync(qUrl,
          new List<string>{ QueueAttributeName.All });
      Console.WriteLine($"Queue: {qUrl}");
      foreach(var att in responseGetAtt.Attributes)
        Console.WriteLine($"\t{att.Key}: {att.Value}");
    }


    //
    // Method to check the name of the attribute
    private static bool ValidAttribute(string attribute)
    {
      var attOk = false;
      var qAttNameType = typeof(QueueAttributeName);
      List<string> qAttNamefields = new List<string>();
      foreach(var field in qAttNameType.GetFields())
       qAttNamefields.Add(field.Name);
      foreach(var name in qAttNamefields)
        if(attribute == name) { attOk = true; break; }
      return attOk;
    }


    //
    // Method to update a queue attribute
    private static async Task UpdateAttribute(
      IAmazonSQS sqsClient, string qUrl, string attribute, string value)
    {
      await sqsClient.SetQueueAttributesAsync(qUrl,
        new Dictionary<string, string>{{attribute, value}});
    }


    //
    // Command-line help
    private static void PrintHelp()
    {
      Console.WriteLine("\nUsage: SQSUpdateQueue -q queue_url [-a attribute -v value]");
      Console.WriteLine("  -q: The URL of the queue you want to update.");
      Console.WriteLine("  -a: The name of the attribute to update.");
      Console.WriteLine("  -v, --value: The value to assign to the attribute.");
    }
  }


  // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
  // Class that represents a command line on the console or terminal.
  // (This is the same for all examples. When you have seen it once, you can ignore it.)
  static class CommandLine
  {
    //
    // Method to parse a command line of the form: "--key value" or "-k value".
    //
    // Parameters:
    // - args: The command-line arguments passed into the application by the system.
    //
    // Returns:
    // A Dictionary with string Keys and Values.
    //
    // If a key is found without a matching value, Dictionary.Value is set to the key
    //  (including the dashes).
    // If a value is found without a matching key, Dictionary.Key is set to "--NoKeyN",
    //  where "N" represents sequential numbers.
    public static Dictionary<string,string> Parse(string[] args)
    {
      var parsedArgs = new Dictionary<string,string>();
      int i = 0, n = 0;
      while(i < args.Length)
      {
        // If the first argument in this iteration starts with a dash it's an option.
        if(args[i].StartsWith("-"))
        {
          var key = args[i++];
          var value = key;

          // Check to see if there's a value that goes with this option?
          if((i < args.Length) && (!args[i].StartsWith("-"))) value = args[i++];
          parsedArgs.Add(key, value);
        }

        // If the first argument in this iteration doesn't start with a dash, it's a value
        else
        {
          parsedArgs.Add("--NoKey" + n.ToString(), args[i++]);
          n++;
        }
      }

      return parsedArgs;
    }

    //
    // Method to get an argument from the parsed command-line arguments
    //
    // Parameters:
    // - parsedArgs: The Dictionary object returned from the Parse() method (shown above).
    // - defaultValue: The default string to return if the specified key isn't in parsedArgs.
    // - keys: An array of keys to look for in parsedArgs.
    public static string GetArgument(
      Dictionary<string,string> parsedArgs, string defaultReturn, params string[] keys)
    {
      string retval = null;
      foreach(var key in keys)
        if(parsedArgs.TryGetValue(key, out retval)) break;
      return retval ?? defaultReturn;
    }

    //
    // Method to exit the application with an error.
    public static void ErrorExit(string msg, int code=1)
    {
      Console.WriteLine("\nError");
      Console.WriteLine(msg);
      Environment.Exit(code);
    }
  }

}
```

## 其他考量
<a name="UpdateSqsQueue-additional"></a>
+ 若要更新 `RedrivePolicy` 屬性，您必須根據您的作業系統，引用整個值並逸出鍵/值對的引號。

  例如，在 Windows 上， 值的建構方式類似如下：

  ```
  "{\"deadLetterTargetArn\":\"DEAD_LETTER-QUEUE-ARN\",\"maxReceiveCount\":\"10\"}"
  ```