Quickstart: Manage blobs with Coffee v12 SDK

  • Article
  • 8 minutes to read

In this quickstart, you lot larn to manage blobs by using Coffee. Blobs are objects that tin can hold large amounts of text or binary data, including images, documents, streaming media, and archive data. Y'all'll upload, download, and list blobs, and you'll create and delete containers.

Additional resources:

  • API reference documentation
  • Library source lawmaking
  • Package (Maven)
  • Samples

Prerequisites

  • An Azure business relationship with an agile subscription. Create an account for free.
  • An Azure Storage account. Create a storage account.
  • Coffee Evolution Kit (JDK) version eight or to a higher place.
  • Apache Maven.

Setting upwardly

This section walks you through preparing a project to work with the Azure Blob Storage client library v12 for Java.

Create the projection

Create a Java application named blob-quickstart-v12.

  1. In a panel window (such as cmd, PowerShell, or Fustigate), use Maven to create a new console app with the name blob-quickstart-v12. Blazon the post-obit mvn command to create a "Hello world!" Coffee project.

    • PowerShell
    • Bash 
                          mvn archetype:generate `     --define interactiveMode=n `     --define groupId=com.blobs.quickstart `     --define artifactId=blob-quickstart-v12 `     --define archetypeArtifactId=maven-archetype-quickstart `     --define archetypeVersion=1.4

  2. The output from generating the projection should wait something like this:

                      [INFO] Scanning for projects... [INFO] [INFO] ------------------< org.apache.maven:standalone-pom >------------------- [INFO] Building Maven Stub Project (No POM) ane [INFO] --------------------------------[ pom ]--------------------------------- [INFO] [INFO] >>> maven-classic-plugin:three.1.2:generate (default-cli) > generate-sources @ standalone-pom >>> [INFO] [INFO] <<< maven-archetype-plugin:3.one.two:generate (default-cli) < generate-sources @ standalone-pom <<< [INFO] [INFO] [INFO] --- maven-archetype-plugin:three.i.2:generate (default-cli) @ standalone-pom --- [INFO] Generating projection in Batch style [INFO] ---------------------------------------------------------------------------- [INFO] Using post-obit parameters for creating project from Archetype: maven-classic-quickstart:i.iv [INFO] ---------------------------------------------------------------------------- [INFO] Parameter: groupId, Value: com.blobs.quickstart [INFO] Parameter: artifactId, Value: hulk-quickstart-v12 [INFO] Parameter: version, Value: 1.0-SNAPSHOT [INFO] Parameter: package, Value: com.blobs.quickstart [INFO] Parameter: packageInPathFormat, Value: com/blobs/quickstart [INFO] Parameter: version, Value: i.0-SNAPSHOT [INFO] Parameter: package, Value: com.blobs.quickstart [INFO] Parameter: groupId, Value: com.blobs.quickstart [INFO] Parameter: artifactId, Value: blob-quickstart-v12 [INFO] Project created from Archetype in dir: C:\QuickStarts\hulk-quickstart-v12 [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Full time:  7.056 south [INFO] Finished at: 2019-ten-23T11:09:21-07:00 [INFO] ------------------------------------------------------------------------     ```

  3. Switch to the newly created blob-quickstart-v12 folder.

                      cd blob-quickstart-v12

  4. In side the hulk-quickstart-v12 directory, create another directory called data. This is where the blob data files will exist created and stored.

                      mkdir information

Install the package

Open up the pom.xml file in your text editor. Add the post-obit dependency element to the group of dependencies.

              <dependency>     <groupId>com.azure</groupId>     <artifactId>azure-storage-hulk</artifactId>     <version>12.xiii.0</version> </dependency>

Set the app framework

From the project directory:

  1. Navigate to the /src/chief/java/com/blobs/quickstart directory
  2. Open the App.coffee file in your editor
  3. Delete the Organisation.out.println("Hi world!"); statement
  4. Add together import directives

Here'south the code:

              parcel com.blobs.quickstart;  /**  * Azure hulk storage v12 SDK quickstart  */ import com.azure.storage.blob.*; import com.azure.storage.hulk.models.*; import java.io.*;  public course App {     public static void chief( String[] args ) throws IOException     {     } }

Copy your credentials from the Azure portal

When the sample application makes a asking to Azure Storage, it must be authorized. To authorize a asking, add your storage business relationship credentials to the awarding as a connexion string. To view your storage business relationship credentials, follow these steps:

  1. Sign in to the Azure portal.

  2. Locate your storage account.

  3. In the storage business relationship menu pane, nether Security + networking, select Access keys. Hither, you lot tin can view the account admission keys and the complete connection cord for each key.

    Screenshot that shows where the access key settings are in the Azure portal

  4. In the Access keys pane, select Evidence keys.

  5. In the key1 section, locate the Connectedness cord value. Select the Copy to clipboard icon to re-create the connection string. You lot'll add the connection cord value to an environment variable in the next department.

    Screenshot showing how to copy a connection string from the Azure portal

Configure your storage connection string

After you re-create the connection string, write it to a new environs variable on the local automobile running the awarding. To set the environment variable, open a console window, and follow the instructions for your operating organisation. Supersede <yourconnectionstring> with your actual connectedness string.

  • Windows
  • Linux and macOS 
                  setx AZURE_STORAGE_CONNECTION_STRING "<yourconnectionstring>"

Later you lot add the environment variable in Windows, you lot must start a new instance of the control window.

Restart programs

Later you add the environment variable, restart any running programs that will need to read the surroundings variable. For case, restart your development surroundings or editor earlier you go on.

Object model

Azure Hulk Storage is optimized for storing massive amounts of unstructured data. Unstructured information is data that does non attach to a particular data model or definition, such as text or binary data. Blob storage offers three types of resources:

  • The storage account
  • A container in the storage account
  • A blob in the container

The following diagram shows the human relationship betwixt these resources.

Diagram of Blob storage architecture

Use the following Java classes to collaborate with these resource:

  • BlobServiceClient: The BlobServiceClient class allows you to manipulate Azure Storage resources and blob containers. The storage business relationship provides the peak-level namespace for the Blob service.
  • BlobServiceClientBuilder: The BlobServiceClientBuilder class provides a fluent builder API to help aid the configuration and instantiation of BlobServiceClient objects.
  • BlobContainerClient: The BlobContainerClient form allows you to manipulate Azure Storage containers and their blobs.
  • BlobClient: The BlobClient class allows you lot to manipulate Azure Storage blobs.
  • BlobItem: The BlobItem class represents individual blobs returned from a telephone call to listBlobs.

Code examples

These case code snippets show you lot how to perform the following with the Azure Blob Storage client library for Java:

  • Get the connection cord
  • Create a container
  • Upload blobs to a container
  • Listing the blobs in a container
  • Download blobs
  • Delete a container

Go the connection string

The code below retrieves the connection cord for the storage account from the environment variable created in the Configure your storage connection string section.

Add this code inside the Main method:

              System.out.println("Azure Blob Storage v12 - Java quickstart sample\n");  // Remember the connection string for apply with the application. The storage // connection string is stored in an environs 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 surroundings variable into account. String connectStr = Arrangement.getenv("AZURE_STORAGE_CONNECTION_STRING");

Create a container

Decide on a name for the new container. The code below appends a UUID value to the container name to ensure that it is unique.

Side by side, create an case of the BlobContainerClient class, then call the create method to actually create the container in your storage account.

Add this code to the end of the Main method:

              // Create a BlobServiceClient object which volition be used to create a container client BlobServiceClient blobServiceClient = new BlobServiceClientBuilder().connectionString(connectStr).buildClient();  //Create a unique name for the container String containerName = "quickstartblobs" + java.util.UUID.randomUUID();  // Create the container and return a container client object BlobContainerClient containerClient = blobServiceClient.createBlobContainer(containerName);

Upload blobs to a container

The following lawmaking snippet:

  1. Creates a text file in the local information directory.
  2. Gets a reference to a BlobClient object by calling the getBlobClient method on the container from the Create a container section.
  3. Uploads the local text file to the blob past calling the uploadFromFile method. This method creates the blob if information technology doesn't already exist, but will not overwrite it if it does.

Add this lawmaking to the end of the Main method:

              // Create a local file in the ./information/ directory for uploading and downloading String localPath = "./data/"; String fileName = "quickstart" + java.util.UUID.randomUUID() + ".txt"; File localFile = new File(localPath + fileName);  // Write text to the file FileWriter writer = new FileWriter(localPath + fileName, true); writer.write("Hello, Globe!"); writer.close();  // Get a reference to a blob BlobClient blobClient = containerClient.getBlobClient(fileName);  System.out.println("\nUploading to Hulk storage as hulk:\due north\t" + blobClient.getBlobUrl());  // Upload the blob blobClient.uploadFromFile(localPath + fileName);

List the blobs in a container

Listing the blobs in the container by calling the listBlobs method. In this case, only i blob has been added to the container, and so the listing performance returns simply that one blob.

Add this code to the end of the Main method:

              Organization.out.println("\nListing blobs...");  // List the blob(southward) in the container. for (BlobItem blobItem : containerClient.listBlobs()) {     System.out.println("\t" + blobItem.getName()); }

Download blobs

Download the previously created hulk past calling the downloadToFile method. The example code adds a suffix of "DOWNLOAD" to the file proper noun so that you tin see both files in local file organisation.

Add together this code to the end of the Chief method:

              // Download the hulk to a local file // Append the string "DOWNLOAD" before the .txt extension so that you tin see both files. Cord downloadFileName = fileName.replace(".txt", "DOWNLOAD.txt"); File downloadedFile = new File(localPath + downloadFileName);  Organization.out.println("\nDownloading blob to\n\t " + localPath + downloadFileName);  blobClient.downloadToFile(localPath + downloadFileName);

Delete a container

The post-obit code cleans up the resources the app created past removing the entire container using the delete method. Information technology as well deletes the local files created by the app.

The app pauses for user input by calling Arrangement.panel().readLine() earlier it deletes the blob, container, and local files. This is a practiced chance to verify that the resource were created correctly, before they are deleted.

Add this code to the end of the Master method:

              // Clean up Organisation.out.println("\nPress the Enter primal to brainstorm clean up"); System.console().readLine();  Organization.out.println("Deleting blob container..."); containerClient.delete();  System.out.println("Deleting the local source and downloaded files..."); localFile.delete(); downloadedFile.delete();  System.out.println("Done");

Run the code

This app creates a test file in your local folder and uploads information technology to Blob storage. The instance so lists the blobs in the container and downloads the file with a new name then that you tin can compare the onetime and new files.

Navigate to the directory containing the pom.xml file and compile the project by using the following mvn command.

              mvn compile

And so, build the parcel.

              mvn package

Run the post-obit mvn command to execute the app.

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

The output of the app is similar to the post-obit example:

              Azure Blob Storage v12 - Coffee quickstart sample  Uploading to Blob storage equally blob:         https://mystorageacct.blob.core.windows.cyberspace/quickstartblobsf9aa68a5-260e-47e6-bea2-2dcfcfa1fd9a/quickstarta9c3a53e-ae9d-4863-8b34-f3d807992d65.txt  List blobs...         quickstarta9c3a53e-ae9d-4863-8b34-f3d807992d65.txt  Downloading blob to         ./data/quickstarta9c3a53e-ae9d-4863-8b34-f3d807992d65DOWNLOAD.txt  Press the Enter key to begin clean upward  Deleting blob container... Deleting the local source and downloaded files... Washed

Before you begin the make clean upward process, check your data folder for the two files. You can open up them and discover that they are identical.

Later you've verified the files, press the Enter fundamental to delete the exam files and cease the demo.

Next steps

In this quickstart, you learned how to upload, download, and listing blobs using Java.

To see Blob storage sample apps, go on to:

  • To acquire more, see the Azure SDK for Java.
  • For tutorials, samples, quickstarts, and other documentation, visit Azure for Coffee cloud developers.