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Google Cloud Storage with Java Quarkus Tutorial

Google Cloud Storage (GCS) is a scalable, fully-managed object storage service for storing and accessing data on Google Cloud. This tutorial will cover the essentials of using GCS with Java Quarkus, including setup, dependencies, configuration, and sample code for integrating GCS with Quarkus applications.

Prerequisites​

  1. Google Cloud SDK: Ensure that the Google Cloud SDK (gcloud) is installed and authenticated.

    gcloud auth login

  2. Project Configuration: Set up your Google Cloud project.

    gcloud config set project <your-project-id>

  3. Java and Quarkus: Ensure that Java and Quarkus CLI are installed.

1. Google Cloud Storage Basics​

GCS uses buckets to store objects (files). Before using GCS with Quarkus, familiarize yourself with basic GCS commands.

Creating a Bucket​

To create a new bucket:

gsutil mb gs://<bucket-name>

Example:

gsutil mb gs://my-quarkus-app-bucket

Listing Buckets​

To list all buckets in the current project:

gsutil ls

Deleting a Bucket​

To delete a bucket (must be empty):

gsutil rb gs://<bucket-name>

2. Setting up Google Cloud Storage for Java Quarkus​

Adding Dependencies​

To integrate GCS with Quarkus, add the following dependencies in your pom.xml file:

<dependency>
    <groupId>com.google.cloud</groupId>
    <artifactId>google-cloud-storage</artifactId>
    <version>2.1.5</version>
</dependency>

<dependency>
    <groupId>io.quarkus</groupId>
    <artifactId>quarkus-arc</artifactId>
</dependency>

3. Configuring Google Cloud Credentials​

  1. Service Account Key: In the Google Cloud Console, create a service account with permissions for GCS (e.g., "Storage Admin" role). Download the JSON key file.

  2. Setting Environment Variable: Set the environment variable for authentication in your development environment.

    export GOOGLE_APPLICATION_CREDENTIALS="/path/to/your-service-account-key.json"

4. Integrating Google Cloud Storage with Quarkus​

Creating a GCS Service in Quarkus​

In your Quarkus project, create a new class CloudStorageService for interacting with GCS.

import com.google.cloud.storage.Blob;
import com.google.cloud.storage.Bucket;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;

import javax.enterprise.context.ApplicationScoped;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;

@ApplicationScoped
public class CloudStorageService {

    private final Storage storage = StorageOptions.getDefaultInstance().getService();
    private final String bucketName = "my-quarkus-app-bucket";

    public String uploadFile(String fileName, Path filePath) throws IOException {
        Bucket bucket = storage.get(bucketName);
        Blob blob = bucket.create(fileName, Files.readAllBytes(filePath));
        return blob.getSelfLink();
    }

    public byte[] downloadFile(String fileName) {
        Blob blob = storage.get(bucketName, fileName);
        return blob.getContent();
    }

    public boolean deleteFile(String fileName) {
        Blob blob = storage.get(bucketName, fileName);
        return blob != null && blob.delete();
    }
}

Sample REST Endpoints for GCS Operations​

Create a REST controller in your Quarkus project to handle HTTP requests for file uploads, downloads, and deletions.

import javax.inject.Inject;
import javax.ws.rs.*;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import java.io.File;
import java.nio.file.Path;

@Path("/gcs")
public class GCSResource {

    @Inject
    CloudStorageService cloudStorageService;

    @POST
    @Path("/upload")
    @Consumes(MediaType.MULTIPART_FORM_DATA)
    public Response uploadFile(@FormParam("filePath") String filePath) {
        try {
            String fileName = Path.of(filePath).getFileName().toString();
            String link = cloudStorageService.uploadFile(fileName, Path.of(filePath));
            return Response.ok("File uploaded: " + link).build();
        } catch (Exception e) {
            return Response.status(Response.Status.INTERNAL_SERVER_ERROR).entity("Upload failed").build();
        }
    }

    @GET
    @Path("/download/{fileName}")
    @Produces(MediaType.APPLICATION_OCTET_STREAM)
    public Response downloadFile(@PathParam("fileName") String fileName) {
        byte[] content = cloudStorageService.downloadFile(fileName);
        return Response.ok(content).header("Content-Disposition", "attachment; filename="" + fileName + """).build();
    }

    @DELETE
    @Path("/delete/{fileName}")
    public Response deleteFile(@PathParam("fileName") String fileName) {
        boolean deleted = cloudStorageService.deleteFile(fileName);
        if (deleted) {
            return Response.ok("File deleted").build();
        } else {
            return Response.status(Response.Status.NOT_FOUND).entity("File not found").build();
        }
    }
}

5. Testing the Application​

Upload a File​

Use a REST client (e.g., Postman) to send a POST request to http://localhost:8080/gcs/upload with the file path as a parameter to upload it to GCS.

Download a File​

Send a GET request to http://localhost:8080/gcs/download/{fileName} to download a file from GCS.

Delete a File​

Send a DELETE request to http://localhost:8080/gcs/delete/{fileName} to delete a file from GCS.

Summary​

This tutorial covered the basics of setting up Google Cloud Storage and integrating it with Java Quarkus. You learned to:

  1. Set up GCS and create buckets for file storage.
  2. Configure authentication with a Google Cloud service account.
  3. Implement file upload, download, and deletion features using Quarkus and GCS.

By following these steps, you can use Google Cloud Storage for secure and scalable file management in your Quarkus applications.

Content Review​

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