使用用戶端程式庫在 Pub/Sub 中發布及接收訊息

使用用戶端程式庫在 Pub/Sub 中發布及接收訊息

透過 Pub/Sub 服務，應用程式就能以可靠、快速、非同步的方式交換訊息。事件順序如下：

1. 資料生產者將訊息發布至 Pub/Sub 主題。
2. 訂閱端用戶端會建立對該主題的訂閱，並提取來自訂閱項目的訊息。

您可以使用下列任一方法設定 Pub/Sub 環境： Google Cloud 控制台、Cloud Shell、用戶端程式庫或 REST API。本頁面說明如何開始使用用戶端程式庫，以 Pub/Sub 發布訊息。

Pub/Sub 提供高階和低階自動產生的用戶端程式庫。根據預設，如本快速入門導覽課程所示，我們建議使用高階用戶端程式庫。

---

如要直接在 Google Cloud 控制台中，按照這項工作的逐步指南操作，請按一下「Guide me」(逐步引導)：

「Guide me」(逐步引導)

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事前準備

登入 Google Cloud 帳戶。如果您是 Google Cloud新手，歡迎 建立帳戶，親自評估產品在實際工作環境中的成效。新客戶還能獲得價值 $300 美元的免費抵免額，可用於執行、測試及部署工作負載。
安裝 Google Cloud CLI。
若您採用的是外部識別資訊提供者 (IdP)，請先使用聯合身分登入 gcloud CLI。
執行下列指令，初始化 gcloud CLI：
gcloud init
建立或選取 Google Cloud 專案。
選取或建立專案所需的角色
• 選取專案：選取專案時，不需要具備特定 IAM 角色，只要您已獲授角色，即可選取任何專案。
• 建立專案：如要建立專案，您需要具備專案建立者角色 (roles/resourcemanager.projectCreator)，其中包含 resourcemanager.projects.create 權限。瞭解如何授予角色。
注意：如果您不打算保留在這項程序中建立的資源，請建立新專案，而不要選取現有專案。完成這些步驟後，您就可以刪除專案，並移除與該專案相關聯的所有資源。
• 建立 Google Cloud 專案：

  gcloud projects create PROJECT_ID

  將 PROJECT_ID 替換為您要建立的 Google Cloud 專案名稱。

• 選取您建立的 Google Cloud 專案：

  gcloud config set project PROJECT_ID

  將 PROJECT_ID 替換為 Google Cloud 專案名稱。
確認專案已啟用計費功能 Google Cloud 。
啟用 Pub/Sub API：
啟用 API 時所需的角色
如要啟用 API，您需要具備服務使用情形管理員 IAM 角色 (roles/serviceusage.serviceUsageAdmin)，其中包含 serviceusage.services.enable 權限。瞭解如何授予角色。
gcloud services enable pubsub.googleapis.com
為使用者帳戶建立本機驗證憑證：
gcloud auth application-default login
注意：如果 gcloud CLI 列印警告訊息，指出您的帳戶沒有 serviceusage.services.use 權限，部分 gcloud CLI 指令和用戶端程式庫可能無法運作。請管理員授予您「服務使用情形消費者」IAM 角色 (roles/serviceusage.serviceUsageConsumer)，然後執行下列指令：
gcloud auth application-default set-quota-project PROJECT_ID
如果系統傳回驗證錯誤，且您使用外部識別資訊提供者 (IdP)，請確認您已 使用聯合身分登入 gcloud CLI。
將角色授予使用者帳戶。針對下列每個 IAM 角色，執行一次下列指令： roles/pubsub.admin
gcloud projects add-iam-policy-binding PROJECT_ID --member="user:USER_IDENTIFIER" --role=ROLE
更改下列內容：
• PROJECT_ID：專案 ID。
• USER_IDENTIFIER：使用者帳戶的 ID。 例如：[e-mail]。
• ROLE：授予使用者帳戶的 IAM 角色。

安裝 Google Cloud CLI。

若您採用的是外部識別資訊提供者 (IdP)，請先使用聯合身分登入 gcloud CLI。

執行下列指令，初始化 gcloud CLI：

gcloud init

建立或選取 Google Cloud 專案。

選取或建立專案所需的角色

• 選取專案：選取專案時，不需要具備特定 IAM 角色，只要您已獲授角色，即可選取任何專案。
• 建立專案：如要建立專案，您需要具備專案建立者角色 (roles/resourcemanager.projectCreator)，其中包含 resourcemanager.projects.create 權限。瞭解如何授予角色。

注意：如果您不打算保留在這項程序中建立的資源，請建立新專案，而不要選取現有專案。完成這些步驟後，您就可以刪除專案，並移除與該專案相關聯的所有資源。

• 建立 Google Cloud 專案：

  gcloud projects create PROJECT_ID

  將 PROJECT_ID 替換為您要建立的 Google Cloud 專案名稱。

• 選取您建立的 Google Cloud 專案：

  gcloud config set project PROJECT_ID

  將 PROJECT_ID 替換為 Google Cloud 專案名稱。

確認專案已啟用計費功能 Google Cloud 。

啟用 Pub/Sub API：

啟用 API 時所需的角色

如要啟用 API，您需要具備服務使用情形管理員 IAM 角色 (roles/serviceusage.serviceUsageAdmin)，其中包含 serviceusage.services.enable 權限。瞭解如何授予角色。

gcloud services enable pubsub.googleapis.com

為使用者帳戶建立本機驗證憑證：

gcloud auth application-default login

注意：如果 gcloud CLI 列印警告訊息，指出您的帳戶沒有 serviceusage.services.use 權限，部分 gcloud CLI 指令和用戶端程式庫可能無法運作。請管理員授予您「服務使用情形消費者」IAM 角色 (roles/serviceusage.serviceUsageConsumer)，然後執行下列指令：

gcloud auth application-default set-quota-project PROJECT_ID

如果系統傳回驗證錯誤，且您使用外部識別資訊提供者 (IdP)，請確認您已 使用聯合身分登入 gcloud CLI。

將角色授予使用者帳戶。針對下列每個 IAM 角色，執行一次下列指令： roles/pubsub.admin

gcloud projects add-iam-policy-binding PROJECT_ID --member="user:USER_IDENTIFIER" --role=ROLE

更改下列內容：

• PROJECT_ID：專案 ID。
• USER_IDENTIFIER：使用者帳戶的 ID。 例如：[e-mail]。
• ROLE：授予使用者帳戶的 IAM 角色。

安裝用戶端程式庫

下列範例說明如何安裝用戶端程式庫：

Python

如要進一步瞭解如何設定 Python 開發環境，請參閱「Python 開發環境設定指南」。

# ensure that you are using virtualenv
# as described in the python dev setup guide

pip install --upgrade google-cloud-pubsub

C++

如要進一步瞭解如何安裝 C++ 程式庫，請參閱 GitHub README

C#

Install-Package Google.Cloud.PubSub.V1 -Pre

Go

go get cloud.google.com/go/pubsub

Java

如果您使用 Maven，請將下列指令新增到 pom.xml 檔案中。如要進一步瞭解 BOM，請參閱 Google Cloud Platform 程式庫 BOM。

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>com.google.cloud</groupId>
      <artifactId>libraries-bom</artifactId>
      <version>26.76.0</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

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

</dependencies>

如果您使用 Gradle，請將下列指令新增到依附元件中：

implementation platform('com.google.cloud:libraries-bom:26.78.0')

implementation 'com.google.cloud:google-cloud-pubsub'

如果您使用 sbt，請在依附元件中加入以下指令：

libraryDependencies += "com.google.cloud" % "google-cloud-pubsub" % "1.150.0"

如果您使用 Visual Studio Code 或 IntelliJ，可以利用下列 IDE 外掛程式，將用戶端程式庫新增到專案中：

• Cloud Code for VS Code
• Cloud Code for IntelliJ

這些外掛程式會提供其他功能，例如服務帳戶的金鑰管理功能。詳情請參閱各外掛程式的說明文件。

注意：Cloud Java 用戶端程式庫目前並不支援 Android。

Node.js

npm install @google-cloud/pubsub

PHP

composer require google/cloud-pubsub

Ruby

gem install google-cloud-pubsub

建立主題與訂閱項目

建立主題後，您就可以訂閱或發布至該主題。

使用下列 gcloud pubsub topics create 指令建立名為 my-topic 的主題。請勿變更主題名稱，因為教學課程的其餘部分會參考這個名稱。

gcloud pubsub topics create my-topic

使用 gcloud pubsub subscriptions create 指令建立訂閱。只有在訂閱後發佈至主題的訊息才能在訂閱者應用程式中找到。

gcloud pubsub subscriptions create my-sub --topic my-topic

注意： 如果收到 400 Invalid resource name given 錯誤訊息，表示資源名稱含有無效字元。如要進一步瞭解如何為主題和訂閱項目命名，請參閱「資源名稱」一文。

發布訊息

執行下列範例前，請務必取消註解並填入程式碼中標示的所有必要值。這是將範例連結至專案和先前建立的 Pub/Sub 資源的必要步驟。

請使用 my-topic 做為主題 ID。

Python

from google.cloud import pubsub_v1

# TODO(developer)
# project_id = "your-project-id"
# topic_id = "your-topic-id"

publisher = pubsub_v1.PublisherClient()
# The `topic_path` method creates a fully qualified identifier
# in the form `projects/{project_id}/topics/{topic_id}`
topic_path = publisher.topic_path(project_id, topic_id)

for n in range(1, 10):
    data_str = f"Message number {n}"
    # Data must be a bytestring
    data = data_str.encode("utf-8")
    # When you publish a message, the client returns a future.
    future = publisher.publish(topic_path, data)
    print(future.result())

print(f"Published messages to {topic_path}.")

C++

#include "google/cloud/pubsub/publisher.h"
#include <iostream>

int main(int argc, char* argv[]) try {
  if (argc != 3) {
    std::cerr << "Usage: " << argv[0] << " <project-id> <topic-id>\n";
    return 1;
  }

  std::string const project_id = argv[1];
  std::string const topic_id = argv[2];

  // Create a namespace alias to make the code easier to read.
  namespace pubsub = ::google::cloud::pubsub;

  auto publisher = pubsub::Publisher(
      pubsub::MakePublisherConnection(pubsub::Topic(project_id, topic_id)));
  auto id =
      publisher
          .Publish(pubsub::MessageBuilder{}.SetData("Hello World!").Build())
          .get();
  if (!id) throw std::move(id).status();
  std::cout << "Hello World published with id=" << *id << "\n";

  return 0;
} catch (google::cloud::Status const& status) {
  std::cerr << "google::cloud::Status thrown: " << status << "\n";
  return 1;
}

C#

using Google.Cloud.PubSub.V1;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

public class PublishMessagesAsyncSample
{
    public async Task<int> PublishMessagesAsync(string projectId, string topicId, IEnumerable<string> messageTexts)
    {
        TopicName topicName = TopicName.FromProjectTopic(projectId, topicId);
        PublisherClient publisher = await PublisherClient.CreateAsync(topicName);

        int publishedMessageCount = 0;
        var publishTasks = messageTexts.Select(async text =>
        {
            try
            {
                string message = await publisher.PublishAsync(text);
                Console.WriteLine($"Published message {message}");
                Interlocked.Increment(ref publishedMessageCount);
            }
            catch (Exception exception)
            {
                Console.WriteLine($"An error occurred when publishing message {text}: {exception.Message}");
            }
        });
        await Task.WhenAll(publishTasks);
        // PublisherClient instance should be shutdown after use.
        // The TimeSpan specifies for how long to attempt to publish locally queued messages.
        await publisher.ShutdownAsync(TimeSpan.FromSeconds(15));
        return publishedMessageCount;
    }
}

Go

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/pubsub/v2"
)

func publish(w io.Writer, projectID, topicID, msg string) error {
	// projectID := "my-project-id"
	// topicID := "my-topic"
	// msg := "Hello World"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("pubsub: NewClient: %w", err)
	}
	defer client.Close()

	// client.Publisher can be passed a topic ID (e.g. "my-topic") or
	// a fully qualified name (e.g. "projects/my-project/topics/my-topic").
	// If a topic ID is provided, the project ID from the client is used.
	// Reuse this publisher for all publish calls to send messages in batches.
	publisher := client.Publisher(topicID)
	result := publisher.Publish(ctx, &pubsub.Message{
		Data: []byte(msg),
	})
	// Block until the result is returned and a server-generated
	// ID is returned for the published message.
	id, err := result.Get(ctx)
	if err != nil {
		return fmt.Errorf("pubsub: result.Get: %w", err)
	}
	fmt.Fprintf(w, "Published a message; msg ID: %v\n", id)
	return nil
}

Java

import com.google.api.core.ApiFuture;
import com.google.cloud.pubsub.v1.Publisher;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.PubsubMessage;
import com.google.pubsub.v1.TopicName;
import java.io.IOException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

public class PublisherExample {
  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";

    publisherExample(projectId, topicId);
  }

  public static void publisherExample(String projectId, String topicId)
      throws IOException, ExecutionException, InterruptedException {
    TopicName topicName = TopicName.of(projectId, topicId);

    Publisher publisher = null;
    try {
      // Create a publisher instance with default settings bound to the topic
      publisher = Publisher.newBuilder(topicName).build();

      String message = "Hello World!";
      ByteString data = ByteString.copyFromUtf8(message);
      PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();

      // Once published, returns a server-assigned message id (unique within the topic)
      ApiFuture<String> messageIdFuture = publisher.publish(pubsubMessage);
      String messageId = messageIdFuture.get();
      System.out.println("Published message ID: " + messageId);
    } finally {
      if (publisher != null) {
        // When finished with the publisher, shutdown to free up resources.
        publisher.shutdown();
        publisher.awaitTermination(1, TimeUnit.MINUTES);
      }
    }
  }
}

Node.js

/**
 * TODO(developer): Uncomment these variables before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';
// const data = JSON.stringify({foo: 'bar'});

// 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 publishMessage(topicNameOrId, data) {
  // Publishes the message as a string, e.g. "Hello, world!" or JSON.stringify(someObject)
  const dataBuffer = Buffer.from(data);

  // Cache topic objects (publishers) and reuse them.
  const topic = pubSubClient.topic(topicNameOrId);

  try {
    const messageId = await topic.publishMessage({data: dataBuffer});
    console.log(`Message ${messageId} published.`);
  } catch (error) {
    console.error(`Received error while publishing: ${error.message}`);
    process.exitCode = 1;
  }
}

Node.js

/**
 * TODO(developer): Uncomment these variables before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';
// const data = JSON.stringify({foo: 'bar'});

// 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 publishMessage(topicNameOrId: string, data: string) {
  // Publishes the message as a string, e.g. "Hello, world!" or JSON.stringify(someObject)
  const dataBuffer = Buffer.from(data);

  // Cache topic objects (publishers) and reuse them.
  const topic = pubSubClient.topic(topicNameOrId);

  try {
    const messageId = await topic.publishMessage({data: dataBuffer});
    console.log(`Message ${messageId} published.`);
  } catch (error) {
    console.error(
      `Received error while publishing: ${(error as Error).message}`,
    );
    process.exitCode = 1;
  }
}

PHP

use Google\Cloud\PubSub\MessageBuilder;
use Google\Cloud\PubSub\PubSubClient;

/**
 * Publishes a message for a Pub/Sub topic.
 *
 * @param string $projectId  The Google project ID.
 * @param string $topicName  The Pub/Sub topic name.
 * @param string $message  The message to publish.
 */
function publish_message($projectId, $topicName, $message)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);

    $topic = $pubsub->topic($topicName);
    $topic->publish((new MessageBuilder)->setData($message)->build());

    print('Message published' . PHP_EOL);
}

Ruby

# topic_id = "your-topic-id"

pubsub = Google::Cloud::PubSub.new
publisher = pubsub.publisher topic_id

publisher.publish "This is a test message."

puts "Message published."

接收郵件

設定訂閱者，以便提取您剛發布的訊息。每個訂閱者都必須確認可設定時間範圍內的每個訊息。未確認的訊息會重新傳送。請注意，Pub/Sub 偶爾會重複傳送訊息，確保所有訊息至少會傳送給訂閱者一次。

執行下列範例前，請務必取消註解並填入程式碼中標示的所有必要值。這是將範例連結至專案和先前建立的 Pub/Sub 資源的必要步驟

使用 my-sub 做為訂閱 ID。

如需更多擷取訊息的範例，請參閱用戶端程式庫程式碼範例。

Python

from concurrent.futures import TimeoutError
from google.cloud import pubsub_v1

# TODO(developer)
# project_id = "your-project-id"
# subscription_id = "your-subscription-id"
# Number of seconds the subscriber should listen for messages
# timeout = 5.0

subscriber = pubsub_v1.SubscriberClient()
# The `subscription_path` method creates a fully qualified identifier
# in the form `projects/{project_id}/subscriptions/{subscription_id}`
subscription_path = subscriber.subscription_path(project_id, subscription_id)

def callback(message: pubsub_v1.subscriber.message.Message) -> None:
    print(f"Received {message}.")
    message.ack()

streaming_pull_future = subscriber.subscribe(subscription_path, callback=callback)
print(f"Listening for messages on {subscription_path}..\n")

# Wrap subscriber in a 'with' block to automatically call close() when done.
with subscriber:
    try:
        # When `timeout` is not set, result() will block indefinitely,
        # unless an exception is encountered first.
        streaming_pull_future.result(timeout=timeout)
    except TimeoutError:
        streaming_pull_future.cancel()  # Trigger the shutdown.
        streaming_pull_future.result()  # Block until the shutdown is complete.

C++

#include "google/cloud/pubsub/message.h"
#include "google/cloud/pubsub/subscriber.h"
#include <iostream>

int main(int argc, char* argv[]) try {
  if (argc != 3) {
    std::cerr << "Usage: " << argv[0] << " <project-id> <subscription-id>\n";
    return 1;
  }

  std::string const project_id = argv[1];
  std::string const subscription_id = argv[2];

  auto constexpr kWaitTimeout = std::chrono::seconds(30);

  // Create a namespace alias to make the code easier to read.
  namespace pubsub = ::google::cloud::pubsub;

  auto subscriber = pubsub::Subscriber(pubsub::MakeSubscriberConnection(
      pubsub::Subscription(project_id, subscription_id)));

  auto session =
      subscriber.Subscribe([&](pubsub::Message const& m, pubsub::AckHandler h) {
        std::cout << "Received message " << m << "\n";
        std::move(h).ack();
      });

  std::cout << "Waiting for messages on " + subscription_id + "...\n";

  // Blocks until the timeout is reached.
  auto result = session.wait_for(kWaitTimeout);
  if (result == std::future_status::timeout) {
    std::cout << "timeout reached, ending session\n";
    session.cancel();
  }

  return 0;
} catch (google::cloud::Status const& status) {
  std::cerr << "google::cloud::Status thrown: " << status << "\n";
  return 1;
}

C#

using Google.Cloud.PubSub.V1;
using System;
using System.Threading;
using System.Threading.Tasks;

public class PullMessagesAsyncSample
{
    public async Task<int> PullMessagesAsync(string projectId, string subscriptionId, bool acknowledge)
    {
        SubscriptionName subscriptionName = SubscriptionName.FromProjectSubscription(projectId, subscriptionId);
        SubscriberClient subscriber = await SubscriberClient.CreateAsync(subscriptionName);
        // SubscriberClient runs your message handle function on multiple
        // threads to maximize throughput.
        int messageCount = 0;
        Task startTask = subscriber.StartAsync((PubsubMessage message, CancellationToken cancel) =>
        {
            string text = message.Data.ToStringUtf8();
            Console.WriteLine($"Message {message.MessageId}: {text}");
            Interlocked.Increment(ref messageCount);
            return Task.FromResult(acknowledge ? SubscriberClient.Reply.Ack : SubscriberClient.Reply.Nack);
        });
        // Run for 5 seconds.
        await Task.Delay(5000);
        await subscriber.StopAsync(CancellationToken.None);
        // Lets make sure that the start task finished successfully after the call to stop.
        await startTask;
        return messageCount;
    }
}

Go

import (
	"context"
	"fmt"
	"io"
	"sync/atomic"
	"time"

	"cloud.google.com/go/pubsub/v2"
)

func pullMsgs(w io.Writer, projectID, subID string) error {
	// projectID := "my-project-id"
	// subID := "my-sub"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("pubsub.NewClient: %w", err)
	}
	defer client.Close()

	// client.Subscriber can be passed a subscription ID (e.g. "my-sub") or
	// a fully qualified name (e.g. "projects/my-project/subscriptions/my-sub").
	// If a subscription ID is provided, the project ID from the client is used.
	sub := client.Subscriber(subID)

	// Receive messages for 10 seconds, which simplifies testing.
	// Comment this out in production, since `Receive` should
	// be used as a long running operation.
	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
	defer cancel()

	var received int32
	err = sub.Receive(ctx, func(_ context.Context, msg *pubsub.Message) {
		fmt.Fprintf(w, "Got message: %q\n", string(msg.Data))
		atomic.AddInt32(&received, 1)
		msg.Ack()
	})
	if err != nil {
		return fmt.Errorf("sub.Receive: %w", err)
	}
	fmt.Fprintf(w, "Received %d messages\n", received)

	return nil
}

Java

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.TimeUnit;
import java.util.concurrent.TimeoutException;

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

    subscribeAsyncExample(projectId, subscriptionId);
  }

  public static void subscribeAsyncExample(String projectId, String subscriptionId) {
    ProjectSubscriptionName subscriptionName =
        ProjectSubscriptionName.of(projectId, subscriptionId);

    // Instantiate an asynchronous message receiver.
    MessageReceiver receiver =
        (PubsubMessage message, AckReplyConsumer consumer) -> {
          // Handle incoming message, then ack the received message.
          System.out.println("Id: " + message.getMessageId());
          System.out.println("Data: " + message.getData().toStringUtf8());
          consumer.ack();
        };

    Subscriber subscriber = null;
    try {
      subscriber = Subscriber.newBuilder(subscriptionName, receiver).build();
      // Start the subscriber.
      subscriber.startAsync().awaitRunning();
      System.out.printf("Listening for messages on %s:\n", subscriptionName.toString());
      // Allow the subscriber to run for 30s unless an unrecoverable error occurs.
      subscriber.awaitTerminated(30, TimeUnit.SECONDS);
    } catch (TimeoutException timeoutException) {
      // Shut down the subscriber after 30s. Stop receiving messages.
      subscriber.stopAsync();
    }
  }
}

Node.js

/**
 * TODO(developer): Uncomment these variables before running the sample.
 */
// const subscriptionNameOrId = 'YOUR_SUBSCRIPTION_NAME_OR_ID';
// const timeout = 60;

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

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

function listenForMessages(subscriptionNameOrId, timeout) {
  // References an existing subscription; if you are unsure if the
  // subscription will exist, try the optimisticSubscribe sample.
  const subscription = pubSubClient.subscription(subscriptionNameOrId);

  // Create an event handler to handle messages
  let messageCount = 0;
  const messageHandler = message => {
    console.log(`Received message ${message.id}:`);
    console.log(`\tData: ${message.data}`);
    console.log(`\tAttributes: ${message.attributes}`);
    messageCount += 1;

    // "Ack" (acknowledge receipt of) the message
    message.ack();
  };

  // Listen for new messages until timeout is hit
  subscription.on('message', messageHandler);

  // Wait a while for the subscription to run. (Part of the sample only.)
  setTimeout(() => {
    subscription.removeListener('message', messageHandler);
    console.log(`${messageCount} message(s) received.`);
  }, timeout * 1000);
}

PHP

use Google\Cloud\PubSub\PubSubClient;

/**
 * Pulls all Pub/Sub messages for a subscription.
 *
 * @param string $projectId  The Google project ID.
 * @param string $subscriptionName  The Pub/Sub subscription name.
 */
function pull_messages($projectId, $subscriptionName)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);
    $subscription = $pubsub->subscription($subscriptionName);
    foreach ($subscription->pull() as $message) {
        printf('Message: %s' . PHP_EOL, $message->data());
        // Acknowledge the Pub/Sub message has been received, so it will not be pulled multiple times.
        $subscription->acknowledge($message);
    }
}

Ruby

# subscription_id = "your-subscription-id"

pubsub = Google::Cloud::PubSub.new
subscriber = pubsub.subscriber subscription_id

listener = subscriber.listen do |received_message|
  puts "Received message: #{received_message.data}"
  received_message.acknowledge!
end

listener.start
# Let the main thread sleep for 60 seconds so the thread for listening
# messages does not quit
sleep 60
listener.stop.wait!

還順利嗎？

可以正常運作！

太好了！ 您對這個快速入門導覽課程有什麼看法？我們有哪些地方需要改善？歡迎提供您的意見！

我遇到問題了。

我們對此深感遺憾。 請說明您遇到的問題，我們會予以修正。

清理 (選用)

1. 如要避免系統向您的 Google Cloud 帳戶收取本指南中所用資源的相關費用，請使用指令列刪除主題和訂閱項目。

     gcloud pubsub subscriptions delete my-sub
     gcloud pubsub topics delete my-topic

2. 選用：撤銷您建立的驗證憑證，並刪除本機憑證檔案。

   gcloud auth application-default revoke

3. 選用：從 gcloud CLI 撤銷憑證。

   gcloud auth revoke

後續步驟

• 進一步瞭解本頁討論的 Pub/Sub 概念。

• 閱讀 Pub/Sub 服務的基本概念。

• 瞭解如何建構一對多 Pub/Sub 系統，建立發布者應用程式，並將訊息發布至兩個不同的訂閱者應用程式。

• 請嘗試其他使用 gcloud CLI 或控制台的 Pub/Sub 快速入門導覽課程。

• 瞭解如何建立主題和發布訊息。

• 選擇或建立訂閱項目。

• 進一步瞭解 Pub/Sub API。

• 瞭解如何使用 Kotlin 執行 Pub/Sub。