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：
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。
#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。
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。
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。
/**
* 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。
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。
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。
# topic_id = "your-topic-id"
require "google/cloud/pubsub"
pubsub = Google::Cloud::Pubsub.new
topic = pubsub.topic topic_id
topic.publish "This is a test message."
puts "Message published."后续步骤
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