发布快速入门

向主题发布消息的快速入门示例。

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：

代码示例

C++

试用此示例之前，请按照 C++ 设置说明进行操作，这些说明位于 Pub/Sub 快速入门：使用 客户端库中。 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。 

#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#

试用此示例之前，请按照 C# Pub/Sub 快速入门（使用 客户端库）中的设置说明进行操作。 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。 


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

试用此示例之前，请按照 Go 设置说明进行操作，具体请参阅 Pub/Sub 快速入门：使用 使用客户端库。 如需了解详情，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/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

试用此示例之前，请按照 Java 设置说明进行操作，具体请参阅 Pub/Sub 快速入门：使用 客户端库。 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.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);
      }
    }
  }
}

PHP

试用此示例之前，请按照 PHP 设置说明进行操作。请按照 Pub/Sub 快速入门：使用 客户端库中的说明进行操作。 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\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

试用此示例之前，请按照 Ruby 设置说明进行操作，具体请参阅 Pub/Sub 快速入门：使用 使用客户端库。 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
publisher = pubsub.publisher topic_id

publisher.publish "This is a test message."

puts "Message published."

Rust

use google_cloud_pubsub::client::Publisher;
use google_cloud_pubsub::model::Message;

pub async fn sample(project_id: &str, topic_id: &str) -> anyhow::Result<()> {
    let topic_name = format!("projects/{project_id}/topics/{topic_id}");
    let publisher = Publisher::builder(topic_name).build().await?;

    let message = Message::new().set_data("Hello, World!");
    let message_id = publisher.publish(message).await?;

    println!("published message with ID: {message_id}");
    Ok(())
}

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。