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创建“仅传送一次”的订阅

创建启用“仅传送一次”的订阅。

深入探索

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仅传送一次

代码示例

C++

在尝试此示例之前，请按照 Pub/Sub 快速入门：使用客户端库中的 C++ 设置说明进行操作。如需了解详情，请参阅 Pub/Sub C++ API 参考文档。

如需向 Pub/Sub 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。

namespace pubsub = ::google::cloud::pubsub;
namespace pubsub_admin = ::google::cloud::pubsub_admin;
[](pubsub_admin::SubscriptionAdminClient client,
   std::string const& project_id, std::string const& topic_id,
   std::string const& subscription_id) {
  google::pubsub::v1::Subscription request;
  request.set_name(
      pubsub::Subscription(project_id, subscription_id).FullName());
  request.set_topic(pubsub::Topic(project_id, topic_id).FullName());
  request.set_enable_exactly_once_delivery(true);
  auto sub = client.CreateSubscription(request);
  if (sub.status().code() == google::cloud::StatusCode::kAlreadyExists) {
    std::cout << "The subscription already exists\n";
    return;
  }
  if (!sub) throw std::move(sub).status();

  std::cout << "The subscription was successfully created: "
            << sub->DebugString() << "\n";
}

C#

在尝试此示例之前，请按照C# Pub/Sub 快速入门：客户端库。如需了解详情，请参阅 Pub/Sub C# API 参考文档。

如需向 Pub/Sub 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。


using Google.Cloud.PubSub.V1;
using Grpc.Core;

public class CreateSubscriptionWithExactlyOnceDeliverySample
{
    public Subscription CreateSubscriptionWithExactlyOnceDelivery(string projectId, string topicId, string subscriptionId)
    {
        SubscriberServiceApiClient subscriber = SubscriberServiceApiClient.Create();
        TopicName topicName = TopicName.FromProjectTopic(projectId, topicId);
        SubscriptionName subscriptionName = SubscriptionName.FromProjectSubscription(projectId, subscriptionId);

        var subscriptionRequest = new Subscription
        {
            SubscriptionName = subscriptionName,
            TopicAsTopicName = topicName,
            EnableExactlyOnceDelivery = true
        };

        Subscription subscription = null;

        try
        {
            subscription = subscriber.CreateSubscription(subscriptionRequest);
        }
        catch (RpcException e) when (e.Status.StatusCode == StatusCode.AlreadyExists)
        {
            // Already exists.  That's fine.
        }
        return subscription;
    }
}

Go

在尝试此示例之前，请按照Go Pub/Sub 快速入门：客户端库。有关详情，请参阅 Pub/Sub Go API 参考文档。

如需向 Pub/Sub 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/pubsub"
)

func createSubscriptionWithExactlyOnceDelivery(w io.Writer, projectID, subID string, topic *pubsub.Topic) error {
	// projectID := "my-project-id"
	// subID := "my-sub"
	// topic of type https://godoc.org/cloud.google.com/go/pubsub#Topic
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("pubsub.NewClient: %w", err)
	}
	defer client.Close()

	sub, err := client.CreateSubscription(ctx, subID, pubsub.SubscriptionConfig{
		Topic:                     topic,
		EnableExactlyOnceDelivery: true,
	})
	if err != nil {
		return err
	}
	fmt.Fprintf(w, "Created a subscription with exactly once delivery enabled: %v\n", sub)
	return nil
}

Java

在尝试此示例之前，请按照Java Pub/Sub 快速入门：客户端库。有关详情，请参阅 Pub/Sub Java API 参考文档。

如需向 Pub/Sub 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。

import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
import com.google.pubsub.v1.ProjectSubscriptionName;
import com.google.pubsub.v1.ProjectTopicName;
import com.google.pubsub.v1.Subscription;
import java.io.IOException;

public class CreateSubscriptionWithExactlyOnceDelivery {
  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    String topicId = "your-topic-id";
    String subscriptionId = "your-subscription-id";

    createSubscriptionWithExactlyOnceDeliveryExample(projectId, topicId, subscriptionId);
  }

  public static void createSubscriptionWithExactlyOnceDeliveryExample(
      String projectId, String topicId, String subscriptionId) throws IOException {
    try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {

      ProjectTopicName topicName = ProjectTopicName.of(projectId, topicId);
      ProjectSubscriptionName subscriptionName =
          ProjectSubscriptionName.of(projectId, subscriptionId);

      Subscription subscription =
          subscriptionAdminClient.createSubscription(
              Subscription.newBuilder()
                  .setName(subscriptionName.toString())
                  .setTopic(topicName.toString())
                  // Enable exactly once delivery in the subscription.
                  .setEnableExactlyOnceDelivery(true)
                  .build());

      System.out.println(
          "Created a subscription with exactly once delivery enabled: "
              + subscription.getAllFields());
    }
  }
}

Node.js

/**
 * TODO(developer): Uncomment these variables before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';
// const subscriptionNameOrId = 'YOUR_SUBSCRIPTION_NAME_OR_ID';

// Imports the Google Cloud client library
const {PubSub} = require('@google-cloud/pubsub');

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function createSubscriptionWithExactlyOnceDelivery(
  topicNameOrId,
  subscriptionNameOrId
) {
  // Creates a new subscription
  await pubSubClient
    .topic(topicNameOrId)
    .createSubscription(subscriptionNameOrId, {
      enableExactlyOnceDelivery: true,
    });
  console.log(
    `Created subscription ${subscriptionNameOrId} with exactly-once delivery.`
  );
  console.log(
    'To process messages, remember to check the return value of ackWithResponse().'
  );
}

Node.js

/**
 * TODO(developer): Uncomment these variables before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';
// const subscriptionNameOrId = 'YOUR_SUBSCRIPTION_NAME_OR_ID';

// Imports the Google Cloud client library
import {PubSub} from '@google-cloud/pubsub';

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function createSubscriptionWithExactlyOnceDelivery(
  topicNameOrId: string,
  subscriptionNameOrId: string
) {
  // Creates a new subscription
  await pubSubClient
    .topic(topicNameOrId)
    .createSubscription(subscriptionNameOrId, {
      enableExactlyOnceDelivery: true,
    });
  console.log(
    `Created subscription ${subscriptionNameOrId} with exactly-once delivery.`
  );
  console.log(
    'To process messages, remember to check the return value of ackWithResponse().'
  );
}

PHP

在尝试此示例之前，请按照PHP Pub/Sub 快速入门：客户端库。如需了解详情，请参阅 Pub/Sub PHP API 参考文档。

如需向 Pub/Sub 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。

use Google\Cloud\PubSub\PubSubClient;

/**
 * Creates a Pub/Sub subscription with `Exactly Once Delivery` enabled.
 *
 * @param string $projectId  The Google project ID.
 * @param string $topicName  The Pub/Sub topic name.
 * @param string $subscriptionName  The Pub/Sub subscription name.
 */
function create_subscription_with_exactly_once_delivery(
    string $projectId,
    string $topicName,
    string $subscriptionName
): void {
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);
    $topic = $pubsub->topic($topicName);
    $subscription = $topic->subscription($subscriptionName);
    $subscription->create([
        'enableExactlyOnceDelivery' => true
    ]);

    // Exactly Once Delivery status for the subscription
    $status = $subscription->info()['enableExactlyOnceDelivery'];

    printf('Subscription created with exactly once delivery status: %s' . PHP_EOL, $status ? 'true' : 'false');
}

Python

在尝试此示例之前，请按照 Pub/Sub 快速入门：使用客户端库中的 Python 设置说明进行操作。如需了解详情，请参阅 Pub/Sub Python API 参考文档。

如需向 Pub/Sub 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。

from google.cloud import pubsub_v1

# TODO(developer): Choose an existing topic.
# project_id = "your-project-id"
# topic_id = "your-topic-id"
# subscription_id = "your-subscription-id"

publisher = pubsub_v1.PublisherClient()
subscriber = pubsub_v1.SubscriberClient()
topic_path = publisher.topic_path(project_id, topic_id)
subscription_path = subscriber.subscription_path(project_id, subscription_id)

with subscriber:
    subscription = subscriber.create_subscription(
        request={
            "name": subscription_path,
            "topic": topic_path,
            "enable_exactly_once_delivery": True,
        }
    )
    print(
        f"Created subscription with exactly once delivery enabled: {subscription}"
    )

Ruby

在尝试此示例之前，请按照Ruby Pub/Sub 快速入门：客户端库。有关详情，请参阅 Pub/Sub Ruby API 参考文档。

如需向 Pub/Sub 进行身份验证，请设置应用默认凭据。如需了解详情，请参阅为本地开发环境设置身份验证。

require "google/cloud/pubsub"

# Shows how to create a new subscription with exactly once delivery enabled
class PubsubCreateSubscriptionWithExactlyOnceDelivery
  def create_subscription_with_exactly_once_delivery project_id:, topic_id:, subscription_id:
    pubsub = Google::Cloud::Pubsub.new project_id: project_id
    topic = pubsub.topic topic_id
    subscription = topic.subscribe subscription_id, enable_exactly_once_delivery: true
    puts "Created subscription with exactly once delivery enabled: #{subscription_id}"
  end

  def self.run
    # TODO(developer): Replace these variables before running the sample.
    project_id = "your-project-id"
    topic_id = "your-topic-id"
    subscription_id = "id-for-new-subcription"
    pubsub_create_subscription_with_exactly_once_delivery = PubsubCreateSubscriptionWithExactlyOnceDelivery.new
    pubsub_create_subscription_with_exactly_once_delivery.create_subscription_with_exactly_once_delivery(
      project_id: project_id,
      topic_id: topic_id,
      subscription_id: subscription_id
    )
  end
end

if $PROGRAM_NAME == __FILE__
  PubsubCreateSubscriptionWithExactlyOnceDelivery.run
end

后续步骤

如需搜索和过滤其他 Google Cloud 产品的代码示例，请参阅 Google Cloud 示例浏览器。