列出主题中的订阅

列出主题中的订阅。

深入探索

如需查看包含此代码示例的详细文档，请参阅以下内容：

• 列出订阅

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。 有关详情，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_admin = ::google::cloud::pubsub_admin;
namespace pubsub = ::google::cloud::pubsub;
[](pubsub_admin::TopicAdminClient client, std::string const& project_id,
   std::string const& topic_id) {
  auto const topic = pubsub::Topic(project_id, topic_id);
  std::cout << "Subscription list for topic " << topic << ":\n";
  for (auto& name : client.ListTopicSubscriptions(topic.FullName())) {
    if (!name) throw std::move(name).status();
    std::cout << "  " << *name << "\n";
  }
}

C#

在尝试此示例之前，请按照C# Pub/Sub 快速入门： 客户端库。 有关详情，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 System.Collections.Generic;

public class ListSubscriptionsInTopicSample
{
    public IEnumerable<string> ListSubscriptionsInTopic(string projectId, string topicId)
    {
        PublisherServiceApiClient publisher = PublisherServiceApiClient.Create();
        TopicName topicName = TopicName.FromProjectTopic(projectId, topicId);
        IEnumerable<string> subscriptions = publisher.ListTopicSubscriptions(topicName);
        return subscriptions;
    }
}

Go

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 Go 设置说明进行操作。 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"

	"cloud.google.com/go/pubsub"
	"google.golang.org/api/iterator"
)

func listSubscriptions(projectID, topicID string) ([]*pubsub.Subscription, error) {
	// projectID := "my-project-id"
	// topicName := "projects/sample-248520/topics/ocr-go-test-topic"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return nil, fmt.Errorf("pubsub.NewClient: %w", err)
	}
	defer client.Close()

	var subs []*pubsub.Subscription

	it := client.Topic(topicID).Subscriptions(ctx)
	for {
		sub, err := it.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			return nil, fmt.Errorf("Next: %w", err)
		}
		subs = append(subs, sub)
	}
	return subs, nil
}

Java

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 Java 设置说明进行操作。 如需了解详情，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.TopicAdminClient;
import com.google.pubsub.v1.TopicName;
import java.io.IOException;

public class ListSubscriptionsInTopicExample {
  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";

    listSubscriptionInTopicExample(projectId, topicId);
  }

  public static void listSubscriptionInTopicExample(String projectId, String topicId)
      throws IOException {
    try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
      TopicName topicName = TopicName.of(projectId, topicId);
      for (String subscription : topicAdminClient.listTopicSubscriptions(topicName).iterateAll()) {
        System.out.println(subscription);
      }
      System.out.println("Listed all the subscriptions in the topic.");
    }
  }
}

Node.js

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_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 listTopicSubscriptions(topicNameOrId) {
  // Lists all subscriptions for the topic
  const [subscriptions] = await pubSubClient
    .topic(topicNameOrId)
    .getSubscriptions();

  console.log(`Subscriptions for ${topicNameOrId}:`);
  subscriptions.forEach(subscription => console.log(subscription.name));
}

Node.js

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';

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

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

async function listTopicSubscriptions(topicNameOrId: string) {
  // Lists all subscriptions for the topic
  const [subscriptions] = await pubSubClient
    .topic(topicNameOrId)
    .getSubscriptions();

  console.log(`Subscriptions for ${topicNameOrId}:`);
  subscriptions.forEach((subscription: Subscription) =>
    console.log(subscription.name)
  );
}

Python

在尝试此示例之前，请按照Python Pub/Sub 快速入门： 客户端库。 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)
# project_id = "your-project-id"
# topic_id = "your-topic-id"

publisher = pubsub_v1.PublisherClient()
topic_path = publisher.topic_path(project_id, topic_id)

response = publisher.list_topic_subscriptions(request={"topic": topic_path})
for subscription in response:
    print(subscription)

Ruby

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 Ruby 设置说明进行操作。 如需了解详情，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。

# topic_id = "your-topic-id"

pubsub = Google::Cloud::Pubsub.new

topic         = pubsub.topic topic_id
subscriptions = topic.subscriptions

puts "Subscriptions in topic #{topic.name}:"
subscriptions.each do |subscription|
  puts subscription.name
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。