的版本 4 (V4) SDK for .NET 正在预览中！要在预览版中查看有关此新版本的信息，请参阅 AWS SDK for .NET （版本 4 预览版）开发者指南。
请注意，SDK 的 V4 处于预览版，因此其内容可能会发生变化。
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
此示例向您展示如何使用更新 Amazon SQS 队列。 SDK for .NET 经过一些检查后，应用程序使用给定值更新给定属性，然后显示队列的所有属性。
如果命令行参数中仅包含队列 URL，则应用程序仅显示队列的所有属性。
以下各节提供了此示例的片段。此后显示了该示例的完整代码，并且可以按原样构建和运行。
显示队列属性
以下代码片段显示了由给定队列 URL 标识的队列的属性。
本主题末尾的示例显示了此片段的使用情况。
//
// 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
以下代码片段验证了正在更新的属性的名称。
本主题末尾的示例显示了此片段的使用情况。
//
// 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
以下代码片段更新了由给定队列 URL 标识的队列属性。
本主题末尾的示例显示了此片段的使用情况。
//
// 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}});
}完整代码
本部分显示了本示例的相关参考和完整代码。
NuGet 包裹：
编程元素：
-
命名空间 Amazon.SQS
Amazon 上课 SQSClient
-
命名空间 Amazon.SQS.Model
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);
}
}
}
额外注意事项
-
要更新
RedrivePolicy属性，必须根据您的操作系统，引用整个值并对键/值对的引号进行转义。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\"}"
