JAVA ON GOOGLE CLOUD PLATFORM

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Build, Deploy, Debug, and Monitor Highly Scalable Java Applications

• Build Java apps on GCP using Eclipse, IntelliJ, or browser based command-line
• Deploy and scale Spring Boot or Spark Java apps
• Use Maven or Gradle build tool plugins to build and deploy to GCP
• Query fully-managed MySQL, PostgreSQL, or NoSQL databases on GCP using Java
• Deploy Java apps to a managed Kubernetes cluster
• Run apps on Google maintained OpenJDK or OpenJDK+Jetty9 Docker images

A Broad Set Of Idiomatic Java APIs & Libraries

Store & archive data within Cloud Storage

Set up fully-managed event-driven messaging with Pub/Sub

Query public data using BigQuery

Translate text in different languages with the Translation API

Analyze images using the Vision API

Store & archive data within Cloud Storage

1

Set up a Cloud Platform Console project

1. Sign in to your Google Account.

   If you don't already have one, sign up for a new account.

2. Set up a GCP Console project.

   Set up a project

   Click to:

   • Create or select a project.
   • Enable the Cloud Storage API for that project.
   • Create a service account.
   • Download a private key as JSON.

   You can view and manage these resources at any time in the GCP Console.

2

Set up a Cloud Storage Bucket

Create a Cloud Storage Bucket:

gsutil mb gs://[YOUR-BUCKET-NAME]

Make the bucket publicly readable so it can serve file:

gsutil defacl set public-read gs://[YOUR_BUCKET_NAME]

3

Add maven dependencies to pom.xml

View on GitHub

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-storage</artifactId>
  <version>1.22.0</version>
</dependency>

4

Add environment variables to app.yaml

View on GitHub

env_variables:
  BUCKET_NAME: YOUR-BUCKET-NAME

5

Write your code

View on GitHub

@SuppressWarnings("serial")
@WebServlet(name = "upload", value = "/upload")
@MultipartConfig()
public class UploadServlet extends HttpServlet {

  private static final String BUCKET_NAME = System.getenv("BUCKET_NAME");
  private static Storage storage = null;

  @Override
  public void init() {
    storage = StorageOptions.getDefaultInstance().getService();
  }

  @Override
  public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException,
      ServletException {
    final Part filePart = req.getPart("file");
    final String fileName = filePart.getSubmittedFileName();

    // Modify access list to allow all users with link to read file
    List<Acl> acls = new ArrayList<>();
    acls.add(Acl.of(Acl.User.ofAllUsers(), Acl.Role.READER));
    // the inputstream is closed by default, so we don't need to close it here
    Blob blob =
        storage.create(
            BlobInfo.newBuilder(BUCKET_NAME, fileName).setAcl(acls).build(),
            filePart.getInputStream());

    // return the public download link
    resp.getWriter().print(blob.getMediaLink());
  }
}

Set up fully-managed event-driven messaging with Pub/Sub.

1

Set up a Cloud Platform Console project

1. Sign in to your Google Account.

   If you don't already have one, sign up for a new account.

2. Set up a GCP Console project.

   Set up a project

   Click to:

   • Create or select a project.
   • Enable the Cloud Pub/Sub API for that project.
   • Create a service account.
   • Download a private key as JSON.

   You can view and manage these resources at any time in the GCP Console.

2

Create a topic and subscription

gcloud beta pubsub topics create YOUR_TOPIC_NAME

gcloud beta pubsub subscriptions create YOUR_SUBSCRIPTION_NAME --topic YOUR_TOPIC_NAME

3

Add maven dependencies to pom.xml

View on GitHub

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-pubsub</artifactId>
  <version>1.38.0</version>
</dependency>

4

Write your code to publish and receive messages

Publish Messages

View on GitHub

import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutureCallback;
import com.google.api.core.ApiFutures;
import com.google.api.gax.rpc.ApiException;
import com.google.cloud.ServiceOptions;
import com.google.cloud.pubsub.v1.Publisher;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.ProjectTopicName;
import com.google.pubsub.v1.PubsubMessage;

public class PublisherExample {

  // use the default project id
  private static final String PROJECT_ID = ServiceOptions.getDefaultProjectId();

  /** Publish messages to a topic.
   * @param args topic name, number of messages
   */
  public static void main(String... args) throws Exception {
    // topic id, eg. "my-topic"
    String topicId = args[0];
    int messageCount = Integer.parseInt(args[1]);
    ProjectTopicName topicName = ProjectTopicName.of(PROJECT_ID, topicId);
    Publisher publisher = null;
    try {
      // Create a publisher instance with default settings bound to the topic
      publisher = Publisher.newBuilder(topicName).build();

      for (int i = 0; i < messageCount; i++) {
        String message = "message-" + i;

        // convert message to bytes
        ByteString data = ByteString.copyFromUtf8(message);
        PubsubMessage pubsubMessage = PubsubMessage.newBuilder()
            .setData(data)
            .build();

        //schedule a message to be published, messages are automatically batched
        ApiFuture<String> future = publisher.publish(pubsubMessage);

        // add an asynchronous callback to handle success / failure
        ApiFutures.addCallback(future, new ApiFutureCallback<String>() {

          @Override
          public void onFailure(Throwable throwable) {
            if (throwable instanceof ApiException) {
              ApiException apiException = ((ApiException) throwable);
              // details on the API exception
              System.out.println(apiException.getStatusCode().getCode());
              System.out.println(apiException.isRetryable());
            }
            System.out.println("Error publishing message : " + message);
          }

          @Override
          public void onSuccess(String messageId) {
            // Once published, returns server-assigned message ids (unique within the topic)
            System.out.println(messageId);
          }
        });
      }
    } finally {
      if (publisher != null) {
        // When finished with the publisher, shutdown to free up resources.
        publisher.shutdown();
      }
    }
  }
}

Subscribe to Messages

View on GitHub

import com.google.cloud.ServiceOptions;
import com.google.cloud.pubsub.v1.AckReplyConsumer;
import com.google.cloud.pubsub.v1.MessageReceiver;
import com.google.cloud.pubsub.v1.Subscriber;
import com.google.pubsub.v1.ProjectSubscriptionName;
import com.google.pubsub.v1.PubsubMessage;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingDeque;

public class SubscriberExample {

  // use the default project id
  private static final String PROJECT_ID = ServiceOptions.getDefaultProjectId();

  private static final BlockingQueue<PubsubMessage> messages = new LinkedBlockingDeque<>();

  static class MessageReceiverExample implements MessageReceiver {

    @Override
    public void receiveMessage(PubsubMessage message, AckReplyConsumer consumer) {
      messages.offer(message);
      consumer.ack();
    }
  }

  /** Receive messages over a subscription. */
  public static void main(String... args) throws Exception {
    // set subscriber id, eg. my-sub
    String subscriptionId = args[0];
    ProjectSubscriptionName subscriptionName = ProjectSubscriptionName.of(
        PROJECT_ID, subscriptionId);
    Subscriber subscriber = null;
    try {
      // create a subscriber bound to the asynchronous message receiver
      subscriber =
          Subscriber.newBuilder(subscriptionName, new MessageReceiverExample()).build();
      subscriber.startAsync().awaitRunning();
      // Continue to listen to messages
      while (true) {
        PubsubMessage message = messages.take();
        System.out.println("Message Id: " + message.getMessageId());
        System.out.println("Data: " + message.getData().toStringUtf8());
      }
    } finally {
      if (subscriber != null) {
        subscriber.stopAsync();
      }
    }
  }
}

Perform data analytics with BigQuery

1

Set up a Cloud Platform Console project

1. Sign in to your Google Account.

   If you don't already have one, sign up for a new account.

2. Set up a GCP Console project.

   Set up a project

   Click to:

   • Create or select a project.
   • Enable the BigQuery API for that project.
   • Create a service account.
   • Download a private key as JSON.

   You can view and manage these resources at any time in the GCP Console.

2

Add maven dependencies to pom.xml

View on GitHub

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-bigquery</artifactId>
  <version>1.38.0</version>
</dependency>

3

Write Your Code

Create a BigQuery service object

View on GitHub

BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();

Query Public Data

View on GitHub

QueryJobConfiguration queryConfig =
    QueryJobConfiguration.newBuilder(
      "SELECT "
          + "CONCAT('https://stackoverflow.com/questions/', CAST(id as STRING)) as url, "
          + "view_count "
          + "FROM `bigquery-public-data.stackoverflow.posts_questions` "
          + "WHERE tags like '%google-bigquery%' "
          + "ORDER BY favorite_count DESC LIMIT 10")
        // Use standard SQL syntax for queries.
        // See: https://cloud.google.com/bigquery/sql-reference/
        .setUseLegacySql(false)
        .build();

// Create a job ID so that we can safely retry.
JobId jobId = JobId.of(UUID.randomUUID().toString());
Job queryJob = bigquery.create(JobInfo.newBuilder(queryConfig).setJobId(jobId).build());

// Wait for the query to complete.
queryJob = queryJob.waitFor();

// Check for errors
if (queryJob == null) {
  throw new RuntimeException("Job no longer exists");
} else if (queryJob.getStatus().getError() != null) {
  // You can also look at queryJob.getStatus().getExecutionErrors() for all
  // errors, not just the latest one.
  throw new RuntimeException(queryJob.getStatus().getError().toString());
}

Displaying Results

View on GitHub

// Get the results.
QueryResponse response = bigquery.getQueryResults(jobId);

TableResult result = queryJob.getQueryResults();

// Print all pages of the results.
for (FieldValueList row : result.iterateAll()) {
  String url = row.get("url").getStringValue();
  long viewCount = row.get("view_count").getLongValue();
  System.out.printf("url: %s views: %d%n", url, viewCount);
}

Translate text in different languages with the Translation API

1

Set up a Cloud Platform Console project

1. Sign in to your Google Account.

   If you don't already have one, sign up for a new account.

2. Set up a GCP Console project.

   Set up a project

   Click to:

   • Create or select a project.
   • Enable the Cloud Translation API for that project.
   • Create a service account.
   • Download a private key as JSON.

   You can view and manage these resources at any time in the GCP Console.

2

Add maven dependencies to pom.xml

View on GitHub

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-translate</artifactId>
  <version>1.38.0</version>
</dependency>

3

Write Your Code

View on GitHub

// Imports the Google Cloud client library
import com.google.cloud.translate.Translate;
import com.google.cloud.translate.Translate.TranslateOption;
import com.google.cloud.translate.TranslateOptions;
import com.google.cloud.translate.Translation;

public class QuickstartSample {
  public static void main(String... args) throws Exception {
    // Instantiates a client
    Translate translate = TranslateOptions.getDefaultInstance().getService();

    // The text to translate
    String text = "Hello, world!";

    // Translates some text into Russian
    Translation translation =
        translate.translate(
            text,
            TranslateOption.sourceLanguage("en"),
            TranslateOption.targetLanguage("ru"));


    System.out.printf("Text: %s%n", text);
    System.out.printf("Translation: %s%n", translation.getTranslatedText());
  }
}

Analyze images using the Vision API

1

Set up a Cloud Platform Console project

1. Sign in to your Google Account.

   If you don't already have one, sign up for a new account.

2. Set up a GCP Console project.

   Set up a project

   Click to:

   • Create or select a project.
   • Enable the Cloud Vision API for that project.
   • Create a service account.
   • Download a private key as JSON.

   You can view and manage these resources at any time in the GCP Console.

2

Add maven dependencies to pom.xml

View on GitHub

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-vision</artifactId>
  <version>1.43.0</version>
</dependency>
<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-storage</artifactId>
  <version>1.43.0</version>
</dependency>

3

Write Your Code

Get Vision Service

View on GitHub

/**
 * Connects to the Vision API using Application Default Credentials.
 */
public static Vision getVisionService() throws IOException, GeneralSecurityException {
  GoogleCredential credential =
      GoogleCredential.getApplicationDefault().createScoped(VisionScopes.all());
  JsonFactory jsonFactory = JacksonFactory.getDefaultInstance();
  return new Vision.Builder(GoogleNetHttpTransport.newTrustedTransport(), jsonFactory, credential)
          .setApplicationName(APPLICATION_NAME)
          .build();
}

Detect Face

View on GitHub

/**
 * Gets up to {@code maxResults} faces for an image stored at {@code path}.
 */
public List<FaceAnnotation> detectFaces(Path path, int maxResults) throws IOException {
  byte[] data = Files.readAllBytes(path);

  AnnotateImageRequest request =
      new AnnotateImageRequest()
          .setImage(new Image().encodeContent(data))
          .setFeatures(ImmutableList.of(
              new Feature()
                  .setType("FACE_DETECTION")
                  .setMaxResults(maxResults)));
  Vision.Images.Annotate annotate =
      vision.images()
          .annotate(new BatchAnnotateImagesRequest().setRequests(ImmutableList.of(request)));
  // Due to a bug: requests to Vision API containing large images fail when GZipped.
  annotate.setDisableGZipContent(true);

  BatchAnnotateImagesResponse batchResponse = annotate.execute();
  assert batchResponse.getResponses().size() == 1;
  AnnotateImageResponse response = batchResponse.getResponses().get(0);
  if (response.getFaceAnnotations() == null) {
    throw new IOException(
        response.getError() != null
            ? response.getError().getMessage()
            : "Unknown error getting image annotations");
  }
  return response.getFaceAnnotations();
}

Highlight faces

View on GitHub

/**
 * Reads image {@code inputPath} and writes {@code outputPath} with {@code faces} outlined.
 */
private static void writeWithFaces(Path inputPath, Path outputPath, List<FaceAnnotation> faces)
    throws IOException {
  BufferedImage img = ImageIO.read(inputPath.toFile());
  annotateWithFaces(img, faces);
  ImageIO.write(img, "jpg", outputPath.toFile());
}

/**
 * Annotates an image {@code img} with a polygon around each face in {@code faces}.
 */
public static void annotateWithFaces(BufferedImage img, List<FaceAnnotation> faces) {
  for (FaceAnnotation face : faces) {
    annotateWithFace(img, face);
  }
}

/**
 * Annotates an image {@code img} with a polygon defined by {@code face}.
 */
private static void annotateWithFace(BufferedImage img, FaceAnnotation face) {
  Graphics2D gfx = img.createGraphics();
  Polygon poly = new Polygon();
  for (Vertex vertex : face.getFdBoundingPoly().getVertices()) {
    poly.addPoint(vertex.getX(), vertex.getY());
  }
  gfx.setStroke(new BasicStroke(5));
  gfx.setColor(new Color(0x00ff00));
  gfx.draw(poly);
}

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Use Java client libraries to send output log statements to Stackdriver.

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