使用模拟器

配置代码以使用模拟器，而不是实际的 Pub/Sub 服务。适用于 C# 和 Java。

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：

• 使用模拟器在本地测试应用

代码示例

C#

试用此示例之前，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。

要向 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.Api.Gax;
using Google.Cloud.PubSub.V1;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;

public class EmulatorSupportSample
{
    public async Task WithEmulatorAsync(string projectId, string topicId, string subscriptionId)
    {
        // Use EmulatorDetection.EmulatorOrProduction to create service clients that will
        // that will connect to the PubSub emulator if the PUBSUB_EMULATOR_HOST environment
        // variable is set, but will otherwise connect to the production environment.

        // Create the PublisherServiceApiClient using the PublisherServiceApiClientBuilder
        // and setting the EmulatorDection property.
        PublisherServiceApiClient publisherService = await new PublisherServiceApiClientBuilder
        {
            EmulatorDetection = EmulatorDetection.EmulatorOrProduction
        }.BuildAsync();

        // Use the client as you'd normally do, to create a topic in this example.
        TopicName topicName = new TopicName(projectId, topicId);
        publisherService.CreateTopic(topicName);

        // Create the SubscriberServiceApiClient using the SubscriberServiceApiClientBuilder
        // and setting the EmulatorDection property.
        SubscriberServiceApiClient subscriberService = await new SubscriberServiceApiClientBuilder
        {
            EmulatorDetection = EmulatorDetection.EmulatorOrProduction
        }.BuildAsync();

        // Use the client as you'd normally do, to create a subscription in this example.
        SubscriptionName subscriptionName = new SubscriptionName(projectId, subscriptionId);
        subscriberService.CreateSubscription(subscriptionName, topicName, pushConfig: null, ackDeadlineSeconds: 60);

        // Create the PublisherClient using PublisherClientBuilder to set the EmulatorDetection property.
        PublisherClient publisher = await new PublisherClientBuilder
        {
            TopicName = topicName,
            EmulatorDetection = EmulatorDetection.EmulatorOrProduction
        }.BuildAsync();
        // Use the client as you'd normally do, to send a message in this example.
        await publisher.PublishAsync("Hello, Pubsub");
        await publisher.ShutdownAsync(TimeSpan.FromSeconds(15));

        // Create the SubscriberClient using SubscriberClientBuild to set the EmulatorDetection property.
        SubscriberClient subscriber = await new SubscriberClientBuilder
        {
            SubscriptionName = subscriptionName,
            EmulatorDetection = EmulatorDetection.EmulatorOrProduction
        }.BuildAsync();
        List<PubsubMessage> receivedMessages = new List<PubsubMessage>();

        // Use the client as you'd normally do, to listen for messages in this example.
        await subscriber.StartAsync((msg, cancellationToken) =>
        {
            receivedMessages.Add(msg);
            Console.WriteLine($"Received message {msg.MessageId} published at {msg.PublishTime.ToDateTime()}");
            Console.WriteLine($"Text: '{msg.Data.ToStringUtf8()}'");
            // In this example we stop the subscriber when the message is received.
            // You may leave the subscriber running, and it will continue to received published messages
            // if any.
            // This is non-blocking, and the returned Task may be awaited.
            subscriber.StopAsync(TimeSpan.FromSeconds(15));
            // Return Reply.Ack to indicate this message has been handled.
            return Task.FromResult(SubscriberClient.Reply.Ack);
        });
    }
}

Java

试用此示例之前，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。

要向 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。

String hostport = System.getenv("PUBSUB_EMULATOR_HOST");
ManagedChannel channel = ManagedChannelBuilder.forTarget(hostport).usePlaintext().build();
try {
  TransportChannelProvider channelProvider =
      FixedTransportChannelProvider.create(GrpcTransportChannel.create(channel));
  CredentialsProvider credentialsProvider = NoCredentialsProvider.create();

  // Set the channel and credentials provider when creating a `TopicAdminClient`.
  // Similarly for SubscriptionAdminClient
  TopicAdminClient topicClient =
      TopicAdminClient.create(
          TopicAdminSettings.newBuilder()
              .setTransportChannelProvider(channelProvider)
              .setCredentialsProvider(credentialsProvider)
              .build());

  TopicName topicName = TopicName.of("my-project-id", "my-topic-id");
  // Set the channel and credentials provider when creating a `Publisher`.
  // Similarly for Subscriber
  Publisher publisher =
      Publisher.newBuilder(topicName)
          .setChannelProvider(channelProvider)
          .setCredentialsProvider(credentialsProvider)
          .build();
} finally {
  channel.shutdown();
}

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。