Windows Azure 系列-- Azure Queue的操作

- Storage Account， 和之前介绍的Azure Table和AzureBlob一样，你需要一个StorageAccount，只需要创建1次AzureStorageAccount就好了，它们3个是共享的。

创建好之后，就可以使用以下属性来访问Azure的Storage了：

private static CloudStorageAccount StorageAccount
        {
            get
            {
                var creds = new StorageCredentials(AccountName, Key);
                var account = new CloudStorageAccount(creds, useHttps: true);
                return account;
            }
        }

- 创建Azure Q

public static void CreateIfNotExist()
        {

            // Create the queue client
            CloudQueueClient queueClient = StorageAccount.CreateCloudQueueClient();
            CloudQueue queue = queueClient.GetQueueReference(OrdersQueue);

            // Create the queue if it doesn‘t already exist
            queue.CreateIfNotExists();
        }

需要注意的就是Q的名字，全部小写。

- 入队

	/// <summary>
        /// add msg to Q
        /// </summary>
        /// <param name="msg"></param>
        public static void AddMsg(string msg)
        {
            CloudQueueClient queueClient = StorageAccount.CreateCloudQueueClient();

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

            // Create a message and add it to the queue.
            CloudQueueMessage message = new CloudQueueMessage(msg);
            queue.AddMessage(message);
        }

代码逻辑很简单，就是向Queue中添加消息。不过要注意，这里只是为了演示没有考虑多线程环境以及并发情形，具体场景中为了不阻塞线程，你通过需要使用Asyn版本的方法，即：

queue.AddMessageAsync(message);

- 拿取指定数量的消息

	/// <summary>
        /// peek a number of messages from Q
        /// </summary>
        /// <param name="count"></param>
        /// <returns></returns>
        public static IList<string> Peek(int count)
        {
            // Create the queue client
            CloudQueueClient queueClient = StorageAccount.CreateCloudQueueClient();

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

            // Peek at the next message
            IEnumerable<CloudQueueMessage> peekedMessages = queue.PeekMessages(count);
            return peekedMessages.Select(m => m.AsString).ToList();
        }

- 出队

	/// <summary>
        /// dequeue a msg
        /// </summary>
        /// <returns></returns>
        public static string DequeueMsg()
        {
            var queueClient = StorageAccount.CreateCloudQueueClient();

            // Retrieve a reference to a queue
            var queue = queueClient.GetQueueReference(OrdersQueue);

            var retrievedMessage = queue.GetMessage();

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

            return retrievedMessage.AsString;
        }

完整的测试代码：

	[TestMethod]
        public void AzureQ_Test()
        {
            // - create Q
            AzureQueueManager.CreateIfNotExist();

            // - Add 5 messages to Q
            for (int i = 0; i < 5; i++)
            {
               AzureQueueManager.AddMsg(string.Format("hello_{0}",i));
            }

            // peek all messages , Assert the order is correct
            var msgs = AzureQueueManager.Peek(5);
            Assert.IsTrue(msgs.Count == 5);
            Assert.IsTrue(msgs[0] == "hello_0");
            Assert.IsTrue(msgs[1] == "hello_1");
            Assert.IsTrue(msgs[2] == "hello_2");
            Assert.IsTrue(msgs[3] == "hello_3");
            Assert.IsTrue(msgs[4] == "hello_4");

            // - dequeue msg
            var msg = AzureQueueManager.DequeueMsg();
            Assert.IsTrue(msg == "hello_0");

            // - peek all messages , assert the first msg has been dequeued
            msgs = AzureQueueManager.Peek(5);
            Assert.IsTrue(msgs.Count == 4);
            Assert.IsTrue(msgs[0] == "hello_1");
            Assert.IsTrue(msgs[1] == "hello_2");
            Assert.IsTrue(msgs[2] == "hello_3");
            Assert.IsTrue(msgs[3] == "hello_4");

        }

测试逻辑在注释中已经全部说明

最后，使用Azure Storage Explorer查看结果：