Google Cloud Programmatic Access from Java

External

• https://googleapis.dev/java/google-cloud-clients/latest/index.html
• https://github.com/googleapis/google-cloud-java

Internal

• Google Cloud Programmatic Access

Service-Specific Libraries

• https://cloud.google.com/storage/docs/reference/libraries

Supported Java Versions

https://cloud.google.com/java/docs/supported-java-versions

Gradle

repositories {
    mavenCentral()
}

dependencies {
    implementation platform('com.google.cloud:libraries-bom:21.0.0')
    implementation 'com.google.cloud:google-cloud-storage'
}

Client Authentication

The programmatic client needs to assume the identity of an already existing service account that has sufficient permissions to access the desired resource.

The service account can be created, if it does not exist already, with gcloud iam service-accounts create. The service account can then be granted permissions on resource with gcloud projects add-iam-policy-binding. A key file for the service account can be generated with gcloud iam service-accounts keys create.

Once the service account key file exists, the programmatic client is configured with the key file by setting the environment variable:

export GOOGLE_APPLICATION_CREDENTIALS="/Users/someuser/tmp/test-sa-key-file.json"

Authentication Test Code

import com.google.api.gax.paging.Page;
import com.google.cloud.storage.Bucket;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;

public class Main {
  public static void main(String[] args) {
    Storage storage = StorageOptions.getDefaultInstance().getService();
    System.out.println("Buckets:");
    Page<Bucket> buckets = storage.list();
    for (Bucket bucket : buckets.iterateAll()) {
      System.out.println(bucket.toString());
    }
  }
}

Alternatively, the client can be explicitly configured.