发布快速入门

向主题发布消息的快速入门示例。

包含此代码示例的文档页面

如需查看上下文中使用的代码示例，请参阅以下文档：

快速入门：使用客户端库

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# 设置说明执行操作。如需了解详情，请参阅 Pub/Sub C# API 参考文档。


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 ocurred when publishing message {text}: {exception.Message}");
            }
        });
        await Task.WhenAll(publishTasks);
        return publishedMessageCount;
    }
}

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。

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

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::runtime_error(id.status().message());
  std::cout << "Hello World published with id=" << *id << "\n";

  return 0;
} catch (std::exception const& ex) {
  std::cerr << "Standard exception raised: " << ex.what() << "\n";
  return 1;
}

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 设置说明执行操作。如需了解详情，请参阅 Pub/Sub Go API 参考文档。

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import (
	"context"
	"fmt"
	"io"

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

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: %v", err)
	}

	t := client.Topic(topicID)
	result := t.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("Get: %v", err)
	}
	fmt.Fprintf(w, "Published a message; msg ID: %v\n", id)
	return 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 设置说明执行操作。如需了解详情，请参阅 Pub/Sub Java API 参考文档。

在 GitHub 上查看反馈


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

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 Node.js 设置说明执行操作。如需了解详情，请参阅 Pub/Sub Node.js API 参考文档。

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/**
 * TODO(developer): Uncomment these variables before running the sample.
 */
// const topicName = 'YOUR_TOPIC_NAME';
// 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() {
  // Publishes the message as a string, e.g. "Hello, world!" or JSON.stringify(someObject)
  const dataBuffer = Buffer.from(data);

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

publishMessage();

PHP

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 PHP 设置说明执行操作。如需了解详情，请参阅 Pub/Sub PHP API 参考文档。

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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(['data' => $message]);
    print('Message published' . PHP_EOL);
}

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 设置说明执行操作。如需了解详情，请参阅 Pub/Sub Python API 参考文档。

在 GitHub 上查看反馈

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 = "Message number {}".format(n)
    # Data must be a bytestring
    data = data.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}.")

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 设置说明执行操作。如需了解详情，请参阅 Pub/Sub Ruby API 参考文档。

在 GitHub 上查看反馈

# topic_name = "Your Pubsub topic name"
require "google/cloud/pubsub"

pubsub = Google::Cloud::Pubsub.new

topic = pubsub.topic topic_name
topic.publish "This is a test message."

puts "Message published."