更新 Amazon SQS 队列 - Amazon SDK for .NET
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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。

更新 Amazon SQS 队列

此示例向您演示如何使用Amazon SDK for .NET以更新 Amazon SQS 队列。经过一些检查后,应用程序会使用给定值更新给定的属性,然后显示队列的所有属性。

如果命令行参数中只包含队列 URL,则应用程序只会显示队列的所有属性。

以下各节提供了此示例的代码段。这些区域有:例子的完整代码在此之后显示,并且可以按原样构建和运行。

显示队列属性

以下代码段显示了由给定队列 URL 标识的队列的属性。

这个示例本主题末尾的显示了这个片段正在使用中。

// // 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}"); }

验证属性名称

以下代码段验证正在更新的属性的名称。

这个示例本主题末尾的显示了这个片段正在使用中。

// // 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; }

更新队列属性

以下代码段更新了由给定队列 URL 标识的队列的属性。

这个示例本主题末尾的显示了这个片段正在使用中。

// // 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}}); }

代码完成

本节显示本示例的相关参考文献和完整代码。

NuGet 软件包:

编程元素:

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); } } }

其他注意事项

  • 更新RedrivePolicy属性时,必须根据您的操作系统引用整个值并转义键/值对的引号。

    例如,在 Windows 上,该值的构造方式类似于以下内容:

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