Proposed Pull Request Change

📄 Document Links

View on GitHub View on Microsoft Learn

--- title: 'Quickstart: Azure Queue Storage client library for Java' description: Learn how to use the Azure Queue Storage client library for Java to create a queue and add messages to it. Then learn how to read and delete messages from the queue. You also learn how to delete a queue. author: pauljewellmsft ms.author: pauljewell ms.date: 06/29/2023 ms.topic: quickstart ms.service: azure-queue-storage ms.devlang: java ms.custom: - devx-track-java - mode-api - passwordless-java - devx-track-extended-java - sfi-ropc-nochange # Customer intent: "As a Java developer, I want to utilize the Queue Storage client library to create and manage queues, so that I can efficiently store and process large numbers of messages in my applications." --- # Quickstart: Azure Queue Storage client library for Java Get started with the Azure Queue Storage client library for Java. Azure Queue Storage is a service for storing large numbers of messages for later retrieval and processing. Follow these steps to install the package and try out example code for basic tasks. [API reference documentation](/java/api/overview/azure/storage-queue-readme) | [Library source code](https://github.com/Azure/azure-sdk-for-java/tree/master/sdk/storage/azure-storage-queue) | [Package (Maven)](https://mvnrepository.com/artifact/com.azure/azure-storage-queue) | [Samples](../common/storage-samples-java.md?toc=/azure/storage/queues/toc.json#queue-samples) Use the Azure Queue Storage client library for Java to: - Create a queue - Add messages to a queue - Peek at messages in a queue - Update a message in a queue - Get the queue length - Receive messages from a queue - Delete messages from a queue - Delete a queue ## Prerequisites - [Java Development Kit (JDK)](/java/azure/jdk/) version 8 or above - [Apache Maven](https://maven.apache.org/download.cgi) - Azure subscription - [create one for free](https://azure.microsoft.com/pricing/purchase-options/azure-account?cid=msft_learn) - Azure Storage account - [create a storage account](../common/storage-account-create.md) ## Setting up This section walks you through preparing a project to work with the Azure Queue Storage client library for Java. ### Create the project Create a Java application named *queues-quickstart*. 1. In a console window (such as cmd, PowerShell, or Bash), use Maven to create a new console app with the name *queues-quickstart*. Type the following `mvn` command to create a "Hello, world!" Java project. # [PowerShell](#tab/powershell) ```powershell mvn archetype:generate ` --define interactiveMode=n ` --define groupId=com.queues.quickstart ` --define artifactId=queues-quickstart ` --define archetypeArtifactId=maven-archetype-quickstart ` --define archetypeVersion=1.4 ``` # [Bash](#tab/bash) ```bash mvn archetype:generate \ --define interactiveMode=n \ --define groupId=com.queues.quickstart \ --define artifactId=queues-quickstart \ --define archetypeArtifactId=maven-archetype-quickstart \ --define archetypeVersion=1.4 ``` --- 1. The output from generating the project should look something like this: ```console [INFO] Scanning for projects... [INFO] [INFO] ------------------< org.apache.maven:standalone-pom >------------------- [INFO] Building Maven Stub Project (No POM) 1 [INFO] --------------------------------[ pom ]--------------------------------- [INFO] [INFO] >>> maven-archetype-plugin:3.1.2:generate (default-cli) > generate-sources @ standalone-pom >>> [INFO] [INFO] <<< maven-archetype-plugin:3.1.2:generate (default-cli) < generate-sources @ standalone-pom <<< [INFO] [INFO] [INFO] --- maven-archetype-plugin:3.1.2:generate (default-cli) @ standalone-pom --- [INFO] Generating project in Batch mode [INFO] ---------------------------------------------------------------------------- [INFO] Using following parameters for creating project from Archetype: maven-archetype-quickstart:1.4 [INFO] ---------------------------------------------------------------------------- [INFO] Parameter: groupId, Value: com.queues.quickstart [INFO] Parameter: artifactId, Value: queues-quickstart [INFO] Parameter: version, Value: 1.0-SNAPSHOT [INFO] Parameter: package, Value: com.queues.quickstart [INFO] Parameter: packageInPathFormat, Value: com/queues/quickstart [INFO] Parameter: version, Value: 1.0-SNAPSHOT [INFO] Parameter: package, Value: com.queues.quickstart [INFO] Parameter: groupId, Value: com.queues.quickstart [INFO] Parameter: artifactId, Value: queues-quickstart [INFO] Project created from Archetype in dir: C:\quickstarts\queues\queues-quickstart [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 6.394 s [INFO] Finished at: 2019-12-03T09:58:35-08:00 [INFO] ------------------------------------------------------------------------ ``` 1. Switch to the newly created *queues-quickstart* directory. ```console cd queues-quickstart ``` ### Install the packages Open the `pom.xml` file in your text editor. Add **azure-sdk-bom** to take a dependency on the latest version of the library. In the following snippet, replace the `{bom_version_to_target}` placeholder with the version number. Using **azure-sdk-bom** keeps you from having to specify the version of each individual dependency. To learn more about the BOM, see the [Azure SDK BOM README](https://github.com/Azure/azure-sdk-for-java/blob/main/sdk/boms/azure-sdk-bom/README.md). ```xml <dependencyManagement> <dependencies> <dependency> <groupId>com.azure</groupId> <artifactId>azure-sdk-bom</artifactId> <version>{bom_version_to_target}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> ``` Then add the following dependency elements to the group of dependencies. The **azure-identity** dependency is needed for passwordless connections to Azure services. ```xml <dependency> <groupId>com.azure</groupId> <artifactId>azure-storage-queue</artifactId> </dependency> <dependency> <groupId>com.azure</groupId> <artifactId>azure-identity</artifactId> </dependency> ``` ### Set up the app framework From the project directory: 1. Navigate to the */src/main/java/com/queues/quickstart* directory 1. Open the *App.java* file in your editor 1. Delete the `System.out.println("Hello, world");` statement 1. Add `import` directives Here's the code: ```java package com.queues.quickstart; /** * Azure Queue Storage client library quickstart */ import com.azure.identity.*; import com.azure.storage.queue.*; import com.azure.storage.queue.models.*; import java.io.*; public class App { public static void main(String[] args) throws IOException { // Quickstart code goes here } } ``` ## Authenticate to Azure [!INCLUDE [passwordless-overview](../../../includes/passwordless/passwordless-overview.md)] ### [Passwordless (Recommended)](#tab/passwordless) `DefaultAzureCredential` is a class provided by the Azure Identity client library for Java. To learn more about `DefaultAzureCredential`, see the [DefaultAzureCredential overview](/java/api/overview/azure/identity-readme#defaultazurecredential). `DefaultAzureCredential` supports multiple authentication methods and determines which method should be used at runtime. This approach enables your app to use different authentication methods in different environments (local vs. production) without implementing environment-specific code. For example, your app can authenticate using your Azure CLI sign-in credentials when developing locally, and then use a [managed identity](../../../articles/active-directory/managed-identities-azure-resources/overview.md) once it has been deployed to Azure. No code changes are required for this transition. [!INCLUDE [storage-queues-create-assign-roles](../../../includes/passwordless/storage-queues/storage-queues-assign-roles.md)] ### [Connection String](#tab/connection-string) [!INCLUDE [storage-quickstart-credentials-include](../../../includes/storage-quickstart-credentials-include.md)] > [!IMPORTANT] > The account access key should be used with caution. If your account access key is lost or accidentally placed in an insecure location, your service may become vulnerable. Anyone who has the access key is able to authorize requests against the storage account, and effectively has access to all the data. `DefaultAzureCredential` provides enhanced security features and benefits and is the recommended approach for managing authorization to Azure services. --- ## Object model Azure Queue Storage is a service for storing large numbers of messages. A queue message can be up to 64 KB in size. A queue may contain millions of messages, up to the total capacity limit of a storage account. Queues are commonly used to create a backlog of work to process asynchronously. Queue Storage offers three types of resources: - **Storage account**: All access to Azure Storage is done through a storage account. For more information about storage accounts, see [Storage account overview](../common/storage-account-overview.md) - **Queue**: A queue contains a set of messages. All messages must be in a queue. Note that the queue name must be all lowercase. For information on naming queues, see [Naming Queues and Metadata](/rest/api/storageservices/Naming-Queues-and-Metadata). - **Message**: A message, in any format, of up to 64 KB. A message can remain in the queue for a maximum of 7 days. For version 2017-07-29 or later, the maximum time-to-live can be any positive number, or -1 indicating that the message doesn't expire. If this parameter is omitted, the default time-to-live is seven days. The following diagram shows the relationship between these resources.  Use the following Java classes to interact with these resources: - [`QueueClientBuilder`](/java/api/com.azure.storage.queue.queueclientbuilder): The `QueueClientBuilder` class configures and instantiates a `QueueClient` object. - [`QueueServiceClient`](/java/api/com.azure.storage.queue.queueserviceclient): The `QueueServiceClient` allows you to manage the all queues in your storage account. - [`QueueClient`](/java/api/com.azure.storage.queue.queueclient): The `QueueClient` class allows you to manage and manipulate an individual queue and its messages. - [`QueueMessageItem`](/java/api/com.azure.storage.queue.models.queuemessageitem): The `QueueMessageItem` class represents the individual objects returned when calling [`ReceiveMessages`](/java/api/com.azure.storage.queue.queueclient.receivemessages) on a queue. ## Code examples These example code snippets show you how to do the following actions with the Azure Queue Storage client library for Java: - [Authorize access and create a client object](#authorize-access-and-create-a-client-object) - [Create a queue](#create-a-queue) - [Add messages to a queue](#add-messages-to-a-queue) - [Peek at messages in a queue](#peek-at-messages-in-a-queue) - [Update a message in a queue](#update-a-message-in-a-queue) - [Get the queue length](#get-the-queue-length) - [Receive and delete messages from a queue](#receive-and-delete-messages-from-a-queue) - [Delete a queue](#delete-a-queue) ## [Passwordless (Recommended)](#tab/passwordless) ### Authorize access and create a client object [!INCLUDE [default-azure-credential-sign-in-no-vs](../../../includes/passwordless/default-azure-credential-sign-in-no-vs.md)] Once authenticated, you can create and authorize a `QueueClient` object using `DefaultAzureCredential` to access queue data in the storage account. `DefaultAzureCredential` automatically discovers and uses the account you signed in with in the previous step. To authorize using `DefaultAzureCredential`, make sure you've added the **azure-identity** dependency in `pom.xml`, as described in [Install the packages](#install-the-packages). Also, be sure to add an import directive for `com.azure.identity` in the *App.java* file: ```java import com.azure.identity.*; ``` Decide on a name for the queue and create an instance of the [`QueueClient`](/java/api/com.azure.storage.queue.queueclient) class, using `DefaultAzureCredential` for authorization. We use this client object to create and interact with the queue resource in the storage account. > [!IMPORTANT] > Queue names may only contain lowercase letters, numbers, and hyphens, and must begin with a letter or a number. Each hyphen must be preceded and followed by a non-hyphen character. The name must also be between 3 and 63 characters long. For more information about naming queues, see [Naming queues and metadata](/rest/api/storageservices/naming-queues-and-metadata). Add this code inside the `main` method, and make sure to replace the `<storage-account-name>` placeholder value: ```java System.out.println("Azure Queue Storage client library - Java quickstart sample\n"); // Create a unique name for the queue String queueName = "quickstartqueues-" + java.util.UUID.randomUUID(); // Instantiate a QueueClient // We'll use this client object to create and interact with the queue // TODO: replace <storage-account-name> with the actual name QueueClient queueClient = new QueueClientBuilder() .endpoint("https://<storage-account-name>.queue.core.windows.net/") .queueName(queueName) .credential(new DefaultAzureCredentialBuilder().build()) .buildClient(); ``` ## [Connection String](#tab/connection-string) ### Get the connection string and create a client The following code retrieves the connection string for the storage account. The connection string is stored in the environment variable created in the [Configure your storage connection string](#configure-your-storage-connection-string) section. Add this code inside the `main` method: ```java System.out.println("Azure Queue Storage client library - Java quickstart sample\n"); // Retrieve the connection string for use with the application. The storage // connection string is stored in an environment variable on the machine // running the application called AZURE_STORAGE_CONNECTION_STRING. If the environment variable // is created after the application is launched in a console or with // Visual Studio, the shell or application needs to be closed and reloaded // to take the environment variable into account. String connectStr = System.getenv("AZURE_STORAGE_CONNECTION_STRING"); ``` Decide on a name for the queue and create an instance of the [`QueueClient`](/java/api/com.azure.storage.queue.queueclient) class, using the connection string for authorization. We use this client object to create and interact with the queue resource in the storage account. > [!IMPORTANT] > Queue names may only contain lowercase letters, numbers, and hyphens, and must begin with a letter or a number. Each hyphen must be preceded and followed by a non-hyphen character. The name must also be between 3 and 63 characters long. For more information, see [Naming queues and metadata](/rest/api/storageservices/naming-queues-and-metadata). Add this code to the end of the `main` method: ```java // Create a unique name for the queue String queueName = "quickstartqueues-" + java.util.UUID.randomUUID(); System.out.println("Creating queue: " + queueName); // Instantiate a QueueClient // We'll use this client object to create and interact with the queue QueueClient queueClient = new QueueClientBuilder() .connectionString(connectStr) .queueName(queueName) .buildClient(); ``` --- > [!NOTE] > Messages sent using the [`QueueClient`](/java/api/com.azure.storage.queue.queueclient) class must be in a format that can be included in an XML request with UTF-8 encoding. You can optionally set the [QueueMessageEncoding](/java/api/com.azure.storage.queue.queuemessageencoding) option to `BASE64` to handle non-compliant messages. ### Create a queue Using the `QueueClient` object, call the [`create`](/java/api/com.azure.storage.queue.queueclient.create) method to create the queue in your storage account. Add this code to the end of the `main` method: ```java System.out.println("Creating queue: " + queueName); // Create the queue queueClient.create(); ``` ### Add messages to a queue The following code snippet adds messages to queue by calling the [`sendMessage`](/java/api/com.azure.storage.queue.queueclient.sendmessage) method. It also saves a [`SendMessageResult`](/java/api/com.azure.storage.queue.models.sendmessageresult) returned from a `sendMessage` call. The result is used to update the message later in the program. Add this code to the end of the `main` method: ```java System.out.println("\nAdding messages to the queue..."); // Send several messages to the queue queueClient.sendMessage("First message"); queueClient.sendMessage("Second message"); // Save the result so we can update this message later SendMessageResult result = queueClient.sendMessage("Third message"); ``` ### Peek at messages in a queue Peek at the messages in the queue by calling the [`peekMessages`](/java/api/com.azure.storage.queue.queueclient.peekmessages) method. This method retrieves one or more messages from the front of the queue but doesn't alter the visibility of the message. Add this code to the end of the `main` method: ```java System.out.println("\nPeek at the messages in the queue..."); // Peek at messages in the queue queueClient.peekMessages(10, null, null).forEach( peekedMessage -> System.out.println("Message: " + peekedMessage.getMessageText())); ``` ### Update a message in a queue Update the contents of a message by calling the [`updateMessage`](/java/api/com.azure.storage.queue.queueclient.updatemessage) method. This method can change a message's visibility timeout and contents. The message content must be a UTF-8 encoded string that is up to 64 KB in size. Along with new content for the message, pass in the message ID and pop receipt by using the `SendMessageResult` that was saved earlier in the code. The message ID and pop receipt identify which message to update. ```java System.out.println("\nUpdating the third message in the queue..."); // Update a message using the result that // was saved when sending the message queueClient.updateMessage(result.getMessageId(), result.getPopReceipt(), "Third message has been updated", Duration.ofSeconds(1)); ``` ### Get the queue length You can get an estimate of the number of messages in a queue. The `getProperties` method returns several values including the number of messages currently in a queue. The count is only approximate because messages can be added or removed after your request. The `getApproximateMessageCount` method returns the last value retrieved by the call to `getProperties`, without calling Queue Storage. ```java QueueProperties properties = queueClient.getProperties(); long messageCount = properties.getApproximateMessagesCount(); System.out.println(String.format("Queue length: %d", messageCount)); ``` ### Receive and delete messages from a queue Download previously added messages by calling the [`receiveMessages`](/java/api/com.azure.storage.queue.queueclient.receivemessages) method. The example code also deletes messages from the queue after they're received and processed. In this case, processing is just displaying the message on the console. The app pauses for user input by calling `System.console().readLine();` before it receives and deletes the messages. Verify in your [Azure portal](https://portal.azure.com) that the resources were created correctly, before they're deleted. Any messages not explicitly deleted eventually become visible in the queue again for another chance to process them. Add this code to the end of the `main` method: ```java System.out.println("\nPress Enter key to receive messages and delete them from the queue..."); System.console().readLine(); // Get messages from the queue queueClient.receiveMessages(10).forEach( // "Process" the message receivedMessage -> { System.out.println("Message: " + receivedMessage.getMessageText()); // Let the service know we're finished with // the message and it can be safely deleted. queueClient.deleteMessage(receivedMessage.getMessageId(), receivedMessage.getPopReceipt()); } ); ``` When calling the `receiveMessages` method, you can optionally specify a value for `maxMessages`, which is the number of messages to retrieve from the queue. The default is 1 message and the maximum is 32 messages. You can also specify a value for `visibilityTimeout`, which hides the messages from other operations for the timeout period. The default is 30 seconds. ### Delete a queue The following code cleans up the resources the app created by deleting the queue using the [`Delete`](/java/api/com.azure.storage.queue.queueclient.delete) method. Add this code to the end of the `main` method: ```java System.out.println("\nPress Enter key to delete the queue..."); System.console().readLine(); // Clean up System.out.println("Deleting queue: " + queueClient.getQueueName()); queueClient.delete(); System.out.println("Done"); ``` ## Run the code This app creates and adds three messages to an Azure queue. The code lists the messages in the queue, then retrieves and deletes them, before finally deleting the queue. In your console window, navigate to your application directory, then build and run the application. ```console mvn compile ``` Then, build the package. ```console mvn package ``` Use the following `mvn` command to run the app. ```console mvn exec:java -Dexec.mainClass="com.queues.quickstart.App" -Dexec.cleanupDaemonThreads=false ``` The output of the app is similar to the following example: ```output Azure Queue Storage client library - Java quickstart sample Adding messages to the queue... Peek at the messages in the queue... Message: First message Message: Second message Message: Third message Updating the third message in the queue... Press Enter key to receive messages and delete them from the queue... Message: First message Message: Second message Message: Third message has been updated Press Enter key to delete the queue... Deleting queue: quickstartqueues-fbf58f33-4d5a-41ac-ac0e-1a05d01c7003 Done ``` When the app pauses before receiving messages, check your storage account in the [Azure portal](https://portal.azure.com). Verify the messages are in the queue. Press the `Enter` key to receive and delete the messages. When prompted, press the `Enter` key again to delete the queue and finish the demo. ## Next steps In this quickstart, you learned how to create a queue and add messages to it using Java code. Then you learned to peek, retrieve, and delete messages. Finally, you learned how to delete a message queue. For tutorials, samples, quick starts, and other documentation, visit: > [!div class="nextstepaction"] > [Azure for Java cloud developers](/azure/developer/java/) - For related code samples using deprecated Java version 8 SDKs, see [Code samples using Java version 8](queues-v8-samples-java.md). - For more Azure Queue Storage sample apps, see [Azure Queue Storage client library for Java - samples](https://github.com/Azure/azure-sdk-for-java/tree/master/sdk/storage/azure-storage-queue/src/samples/java/com/azure/storage/queue).