透過錯誤處理機制發布

透過錯誤處理常式發布訊息。

深入探索

如需包含這個程式碼範例的詳細說明文件，請參閱下列文章：

程式碼範例

C++

在試用這個範例之前，請先按照「使用用戶端程式庫的 Pub/Sub 快速入門導覽課程」中的 C++ 設定說明操作。詳情請參閱 Pub/Sub C++ API 參考文件。

如要向 Pub/Sub 進行驗證，請設定應用程式預設憑證。詳情請參閱「為本機開發環境設定驗證機制」。

namespace pubsub = ::google::cloud::pubsub;
using ::google::cloud::future;
using ::google::cloud::StatusOr;
[](pubsub::Publisher publisher) {
  auto message_id = publisher.Publish(
      pubsub::MessageBuilder{}.SetData("Hello World!").Build());
  auto done = message_id.then([](future<StatusOr<std::string>> f) {
    auto id = f.get();
    if (!id) throw std::move(id).status();
    std::cout << "Hello World! published with id=" << *id << "\n";
  });
  // Block until the message is published
  done.get();
}

C#

在試用這個範例之前，請先按照「使用用戶端程式庫的 Pub/Sub 快速入門導覽課程」中的 C# 設定說明操作。詳情請參閱 Pub/Sub C# API 參考文件。

如要向 Pub/Sub 進行驗證，請設定應用程式預設憑證。詳情請參閱「為本機開發環境設定驗證機制」。


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

在試用這個範例之前，請先按照「使用用戶端程式庫的 Pub/Sub 快速入門導覽課程」中的 Go 設定說明操作。詳情請參閱 Pub/Sub Go API 參考文件。

如要向 Pub/Sub 進行驗證，請設定應用程式預設憑證。詳情請參閱「為本機開發環境設定驗證機制」。

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

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

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

	var wg sync.WaitGroup
	var totalErrors uint64

	// 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)

	for i := 0; i < n; i++ {
		result := publisher.Publish(ctx, &pubsub.Message{
			Data: []byte("Message " + strconv.Itoa(i)),
		})

		wg.Add(1)
		go func(i int, res *pubsub.PublishResult) {
			defer wg.Done()
			// The Get method blocks until a server-generated ID or
			// an error is returned for the published message.
			id, err := res.Get(ctx)
			if err != nil {
				// Error handling code can be added here.
				fmt.Fprintf(w, "Failed to publish: %v", err)
				atomic.AddUint64(&totalErrors, 1)
				return
			}
			fmt.Fprintf(w, "Published message %d; msg ID: %v\n", i, id)
		}(i, result)
	}

	wg.Wait()

	if totalErrors > 0 {
		return fmt.Errorf("%d of %d messages did not publish successfully", totalErrors, n)
	}
	return nil
}

Java

在試用這個範例之前，請先按照「使用用戶端程式庫的 Pub/Sub 快速入門導覽課程」中的 Java 設定說明操作。詳情請參閱 Pub/Sub Java API 參考文件。

如要向 Pub/Sub 進行驗證，請設定應用程式預設憑證。詳情請參閱「為本機開發環境設定驗證機制」。


import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutureCallback;
import com.google.api.core.ApiFutures;
import com.google.api.gax.rpc.ApiException;
import com.google.cloud.pubsub.v1.Publisher;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.PubsubMessage;
import com.google.pubsub.v1.TopicName;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.TimeUnit;

public class PublishWithErrorHandlerExample {

  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";

    publishWithErrorHandlerExample(projectId, topicId);
  }

  public static void publishWithErrorHandlerExample(String projectId, String topicId)
      throws IOException, 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();

      List<String> messages = Arrays.asList("first message", "second message");

      for (final String message : messages) {
        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> future = publisher.publish(pubsubMessage);

        // Add an asynchronous callback to handle success / failure
        ApiFutures.addCallback(
            future,
            new ApiFutureCallback<String>() {

              @Override
              public void onFailure(Throwable throwable) {
                if (throwable instanceof ApiException) {
                  ApiException apiException = ((ApiException) throwable);
                  // details on the API exception
                  System.out.println(apiException.getStatusCode().getCode());
                  System.out.println(apiException.isRetryable());
                }
                System.out.println("Error publishing message : " + message);
              }

              @Override
              public void onSuccess(String messageId) {
                // Once published, returns server-assigned message ids (unique within the topic)
                System.out.println("Published message ID: " + messageId);
              }
            },
            MoreExecutors.directExecutor());
      }
    } finally {
      if (publisher != null) {
        // When finished with the publisher, shutdown to free up resources.
        publisher.shutdown();
        publisher.awaitTermination(1, TimeUnit.MINUTES);
      }
    }
  }
}

Ruby

在試用這個範例之前，請先按照「使用用戶端程式庫的 Pub/Sub 快速入門導覽課程」中的 Ruby 設定說明操作。詳情請參閱 Pub/Sub Ruby API 參考文件。

如要向 Pub/Sub 進行驗證，請設定應用程式預設憑證。詳情請參閱「為本機開發環境設定驗證機制」。

# topic_id = "your-topic-id"

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

begin
  publisher.publish_async "This is a test message." do |result|
    raise "Failed to publish the message." unless result.succeeded?
    puts "Message published asynchronously."
  end
  # Stop the async_publisher to send all queued messages immediately.
  publisher.async_publisher.stop.wait!
rescue StandardError => e
  puts "Received error while publishing: #{e.message}"
end

後續步驟

如要搜尋及篩選其他 Google Cloud 產品的程式碼範例，請參閱Google Cloud 範例瀏覽工具。