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Quickstart: Azure Queue Storage client library for Java	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.	pauljewellmsft	pauljewell	06/29/2023	quickstart	azure-queue-storage	java	devx-track-java, mode-api, passwordless-java, devx-track-extended-java

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 | Library source code | Package (Maven) | 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) version 8 or above
Apache Maven
Azure subscription - create one for free
Azure Storage account - create a storage account

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.

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

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

mvn archetype:generate \
    --define interactiveMode=n \
    --define groupId=com.queues.quickstart \
    --define artifactId=queues-quickstart \
    --define archetypeArtifactId=maven-archetype-quickstart \
    --define archetypeVersion=1.4

The output from generating the project should look something like this:

[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] ------------------------------------------------------------------------

Switch to the newly created queues-quickstart directory.
```
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.

<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.

<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:

Navigate to the /src/main/java/com/queues/quickstart directory
Open the App.java file in your editor
Delete the System.out.println("Hello, world"); statement
Add import directives

Here's the code:

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]

Passwordless (Recommended)

DefaultAzureCredential is a class provided by the Azure Identity client library for Java. To learn more about DefaultAzureCredential, see the DefaultAzureCredential overview. 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 once it has been deployed to Azure. No code changes are required for this transition.

[!INCLUDE storage-queues-create-assign-roles]

Connection String

[!INCLUDE storage-quickstart-credentials-include]

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
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.
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: The QueueClientBuilder class configures and instantiates a QueueClient object.
QueueServiceClient: The QueueServiceClient allows you to manage the all queues in your storage account.
QueueClient: The QueueClient class allows you to manage and manipulate an individual queue and its messages.
QueueMessageItem: The QueueMessageItem class represents the individual objects returned when calling 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
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 and delete messages from a queue
Delete a queue

Passwordless (Recommended)

Authorize access and create a client object

[!INCLUDE default-azure-credential-sign-in-no-vs]

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. Also, be sure to add an import directive for com.azure.identity in the App.java file:

import com.azure.identity.*;

Decide on a name for the queue and create an instance of the 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.

Add this code inside the main method, and make sure to replace the <storage-account-name> placeholder value:

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

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 section.

Add this code inside the main method:

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 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.

Add this code to the end of the main method:

// 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 class must be in a format that can be included in an XML request with UTF-8 encoding. You can optionally set the QueueMessageEncoding option to BASE64 to handle non-compliant messages.

Create a queue

Using the QueueClient object, call the create method to create the queue in your storage account.

Add this code to the end of the main method:

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 method. It also saves a 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:

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 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:

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 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.

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.

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 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 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:

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 method.

Add this code to the end of the main method:

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.

mvn compile

Then, build the package.

mvn package

Use the following mvn command to run the app.

mvn exec:java -Dexec.mainClass="com.queues.quickstart.App" -Dexec.cleanupDaemonThreads=false

The output of the app is similar to the following example:

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. 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

For related code samples using deprecated Java version 8 SDKs, see Code samples using Java version 8.
For more Azure Queue Storage sample apps, see Azure Queue Storage client library for Java - samples.

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storage-quickstart-queues-java.md

storage-quickstart-queues-java.md

Quickstart: Azure Queue Storage client library for Java

Prerequisites

Setting up

Create the project

PowerShell

Bash

Install the packages

Set up the app framework

Authenticate to Azure

Passwordless (Recommended)

Connection String

Object model

Code examples

Passwordless (Recommended)

Authorize access and create a client object

Connection String

Get the connection string and create a client

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 and delete messages from a queue

Delete a queue

Run the code

Next steps

Files

storage-quickstart-queues-java.md

Latest commit

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storage-quickstart-queues-java.md

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Quickstart: Azure Queue Storage client library for Java

Prerequisites

Setting up

Create the project

PowerShell

Bash

Install the packages

Set up the app framework

Authenticate to Azure

Passwordless (Recommended)

Connection String

Object model

Code examples

Passwordless (Recommended)

Authorize access and create a client object

Connection String

Get the connection string and create a client

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 and delete messages from a queue

Delete a queue

Run the code

Next steps