使用 .NET 11.x 版用戶端程式庫的 Azure 佇列儲存體程式碼範例

文章
07/24/2023

本文將說明使用了 Azure 佇列儲存體用戶端程式庫的程式碼範例 (適用於 .NET 11.x 版)。

在 2023 年 3 月 31 日，我們已淘汰不符合目前 Azure SDK 指導方針的 Azure SDK 程式庫支援。新的 Azure SDK 程式庫會定期更新，以促進一致的體驗並加強您的安全性態勢。建議您轉換至新的 Azure SDK 程式庫，以利用新功能和重大安全性更新。

雖然較舊的程式庫仍可在 2023 年 3 月 31 日之後使用，但它們將不再收到 Microsoft 的官方支援和更新。如需詳細資訊，請參閱支援淘汰公告。

如需使用最新 12.x 版用戶端程式庫的程式碼範例，請參閱快速入門：適用於 .NET 的 Azure 佇列儲存體用戶端程式庫。

建立佇列儲存體用戶端

CloudQueueClient 類別可讓您擷取佇列儲存體中儲存的佇列。以下為建立服務用戶端的一種方式：

// Retrieve storage account from connection string
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    CloudConfigurationManager.GetSetting("StorageConnectionString"));

// Create the queue client
CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

建立佇列

此範例顯示如何建立佇列：

// Retrieve storage account from connection string
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    CloudConfigurationManager.GetSetting("StorageConnectionString"));

// Create the queue client
CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

// Retrieve a reference to a queue
CloudQueue queue = queueClient.GetQueueReference("myqueue");

// Create the queue if it doesn't already exist
queue.CreateIfNotExists();

將訊息插入佇列

若要將訊息插入現有佇列，請先建立新的 CloudQueueMessage。接著呼叫 AddMessage 方法。您可以從字串 (採用 UTF-8 格式) 或位元組陣列建立 CloudQueueMessage。下列程式碼範例會建立佇列 (如果不存在) 並插入訊息 Hello, World：

// Retrieve storage account from connection string
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    CloudConfigurationManager.GetSetting("StorageConnectionString"));

// Create the queue client
CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

// Retrieve a reference to a queue
CloudQueue queue = queueClient.GetQueueReference("myqueue");

// Create the queue if it doesn't already exist
queue.CreateIfNotExists();

// Create a message and add it to the queue
CloudQueueMessage message = new CloudQueueMessage("Hello, World");
queue.AddMessage(message);

查看下一則訊息

透過呼叫 PeekMessage 方法，您可以在佇列前面查看訊息，而無需將其從佇列中移除。

// Retrieve storage account from connection string
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    CloudConfigurationManager.GetSetting("StorageConnectionString"));

// Create the queue client
CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

// Retrieve a reference to a queue
CloudQueue queue = queueClient.GetQueueReference("myqueue");

// Peek at the next message
CloudQueueMessage peekedMessage = queue.PeekMessage();

// Display message.
Console.WriteLine(peekedMessage.AsString);

變更佇列訊息的內容

// Retrieve storage account from connection string.
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    CloudConfigurationManager.GetSetting("StorageConnectionString"));

// Create the queue client.
CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

// Retrieve a reference to a queue.
CloudQueue queue = queueClient.GetQueueReference("myqueue");

// Get the message from the queue and update the message contents.
CloudQueueMessage message = queue.GetMessage();
message.SetMessageContent2("Updated contents.", false);
queue.UpdateMessage(message,
    TimeSpan.FromSeconds(60.0),  // Make it invisible for another 60 seconds.
    MessageUpdateFields.Content | MessageUpdateFields.Visibility);

清除佇列中的下一則訊息

您的程式碼可以使用兩個步驟來清除佇列訊息。呼叫 GetMessage 時會取得佇列中的下一則訊息。讀取此佇列訊息的任何其他程式碼皆無法看到從 GetMessage 傳回的訊息。依預設，此訊息會隱藏 30 秒。若要完成移除佇列訊息，您也必須呼叫 DeleteMessage。這個刪除訊息的兩步驟流程可確保當程式碼因硬體或軟體故障而無法處理訊息時，程式碼的其他執行個體可取得相同訊息並再試一次。已處理訊息後，程式碼便會立即呼叫 DeleteMessage。

// Retrieve storage account from connection string
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    CloudConfigurationManager.GetSetting("StorageConnectionString"));

// Create the queue client
CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

// Retrieve a reference to a queue
CloudQueue queue = queueClient.GetQueueReference("myqueue");

// Get the next message
CloudQueueMessage retrievedMessage = queue.GetMessage();

//Process the message in less than 30 seconds, and then delete the message
queue.DeleteMessage(retrievedMessage);

搭配通用佇列儲存體 API 使用 async-await 模式

// Create the queue if it doesn't already exist
if(await queue.CreateIfNotExistsAsync())
{
    Console.WriteLine("Queue '{0}' Created", queue.Name);
}
else
{
    Console.WriteLine("Queue '{0}' Exists", queue.Name);
}

// Create a message to put in the queue
CloudQueueMessage cloudQueueMessage = new CloudQueueMessage("My message");

// Async enqueue the message
await queue.AddMessageAsync(cloudQueueMessage);
Console.WriteLine("Message added");

// Async dequeue the message
CloudQueueMessage retrievedMessage = await queue.GetMessageAsync();
Console.WriteLine("Retrieved message with content '{0}'", retrievedMessage.AsString);

// Async delete the message
await queue.DeleteMessageAsync(retrievedMessage);
Console.WriteLine("Deleted message");

使用其他選項來清除佇列訊息

下列程式碼範例將使用 GetMessages 方法，在一次呼叫中取得 20 個訊息。接著其會使用 foreach 迴圈處理每個訊息。它也會將可見度逾時設定為每個訊息五分鐘。系統會針對所有訊息同時開始逾時，所以從呼叫 GetMessages 開始的 5 分鐘後，任何尚未刪除的訊息都會重新出現。

// Retrieve storage account from connection string.
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    CloudConfigurationManager.GetSetting("StorageConnectionString"));

// Create the queue client.
CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

// Retrieve a reference to a queue.
CloudQueue queue = queueClient.GetQueueReference("myqueue");

foreach (CloudQueueMessage message in queue.GetMessages(20, TimeSpan.FromMinutes(5)))
{
    // Process all messages in less than 5 minutes, deleting each message after processing.
    queue.DeleteMessage(message);
}

取得佇列長度

您可估計佇列中的訊息數目。 FetchAttributes 方法會傳回包含訊息計數在內的佇列屬性。 ApproximateMessageCount 屬性會傳回 FetchAttributes 方法所擷取的最後一個值，而無須呼叫佇列儲存體。

// Retrieve storage account from connection string.
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    CloudConfigurationManager.GetSetting("StorageConnectionString"));

// Create the queue client.
CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

// Retrieve a reference to a queue.
CloudQueue queue = queueClient.GetQueueReference("myqueue");

// Fetch the queue attributes.
queue.FetchAttributes();

// Retrieve the cached approximate message count.
int cachedMessageCount = queue.ApproximateMessageCount;

// Display number of messages.
Console.WriteLine("Number of messages in queue: " + cachedMessageCount);

刪除佇列

若要刪除佇列和其所含的所有訊息，請在佇列物件上呼叫 Delete 方法。

// Retrieve storage account from connection string.
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    CloudConfigurationManager.GetSetting("StorageConnectionString"));

// Create the queue client.
CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();

// Retrieve a reference to a queue.
CloudQueue queue = queueClient.GetQueueReference("myqueue");

// Delete the queue.
queue.Delete();

使用佇列

相關文章：在 .NET 中使用 Azure 佇列儲存體佇列

在您的專案目錄中，使用 dotnet add package 命令新增下列套件：

dotnet add package Microsoft.Azure.Storage.Common

dotnet add package Microsoft.Azure.Storage.Queue

完整程式碼範例：

using System;
using System.Threading.Tasks;
using Microsoft.Azure.Storage;
using Microsoft.Azure.Storage.Queue;

namespace QueueApp
{
    class Program
    {
        static async Task Main(string[] args)
        {
            string connectionString = Environment.GetEnvironmentVariable("AZURE_STORAGE_CONNECTION_STRING");

            CloudStorageAccount storageAccount = CloudStorageAccount.Parse(connectionString);
            CloudQueueClient queueClient = storageAccount.CreateCloudQueueClient();
            CloudQueue queue = queueClient.GetQueueReference("mystoragequeue");

            if (args.Length > 0)
            {
                string value = String.Join(" ", args);
                await InsertMessageAsync(queue, value);
                Console.WriteLine($"Sent: {value}");
            }
            else
            {
                string value = await RetrieveNextMessageAsync(queue);
                Console.WriteLine($"Received: {value}");
            }

            Console.Write("Press Enter...");
            Console.ReadLine();
        }

        static async Task InsertMessageAsync(CloudQueue theQueue, string newMessage)
        {
            if (await theQueue.CreateIfNotExistsAsync())
            {
                Console.WriteLine("The queue was created.");
            }

            CloudQueueMessage message = new CloudQueueMessage(newMessage);
            await theQueue.AddMessageAsync(message);
        }

        static async Task<string> RetrieveNextMessageAsync(CloudQueue theQueue)
        {
            bool exists = await theQueue.ExistsAsync();

            if (exists)
            {
                CloudQueueMessage retrievedMessage = await theQueue.GetMessageAsync();

                if (retrievedMessage != null)
                {
                    string theMessage = retrievedMessage.AsString;
                    await theQueue.DeleteMessageAsync(retrievedMessage);
                    return theMessage;
                }
                else
                {
                    Console.Write("The queue is empty. Attempt to delete it? (Y/N) ");
                    string response = Console.ReadLine();

                    if (response.ToUpper() == "Y")
                    {
                        await theQueue.DeleteIfExistsAsync();
                        return "The queue was deleted.";
                    }
                    else
                    {
                        return "The queue was not deleted.";
                    }
                }
            }
            else
            {
                return "The queue does not exist. Add a message to the command line to create the queue and store the message.";
            }
        }
    }
}

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