发布

将消息发布到单分区精简版主题,并异步解决未来的发布。

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

Java

import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutures;
import com.google.api.gax.rpc.ApiException;
import com.google.cloud.pubsublite.CloudRegion;
import com.google.cloud.pubsublite.CloudZone;
import com.google.cloud.pubsublite.ProjectNumber;
import com.google.cloud.pubsublite.PublishMetadata;
import com.google.cloud.pubsublite.TopicName;
import com.google.cloud.pubsublite.TopicPath;
import com.google.cloud.pubsublite.cloudpubsub.Publisher;
import com.google.cloud.pubsublite.cloudpubsub.PublisherSettings;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.PubsubMessage;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;

public class PublisherExample {

  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String cloudRegion = "your-cloud-region";
    char zoneId = 'b';
    // Choose an existing topic for the publish example to work.
    String topicId = "your-topic-id";
    long projectNumber = Long.parseLong("123456789");
    int messageCount = 100;

    publisherExample(cloudRegion, zoneId, projectNumber, topicId, messageCount);
  }

  // Publish messages to a topic.
  public static void publisherExample(
      String cloudRegion, char zoneId, long projectNumber, String topicId, int messageCount)
      throws ApiException, ExecutionException, InterruptedException {

    TopicPath topicPath =
        TopicPath.newBuilder()
            .setProject(ProjectNumber.of(projectNumber))
            .setLocation(CloudZone.of(CloudRegion.of(cloudRegion), zoneId))
            .setName(TopicName.of(topicId))
            .build();
    Publisher publisher = null;
    List<ApiFuture<String>> futures = new ArrayList<>();

    try {
      PublisherSettings publisherSettings =
          PublisherSettings.newBuilder().setTopicPath(topicPath).build();

      publisher = Publisher.create(publisherSettings);

      // Start the publisher. Upon successful starting, its state will become RUNNING.
      publisher.startAsync().awaitRunning();

      for (int i = 0; i < messageCount; i++) {
        String message = "message-" + i;

        // Convert the message to a byte string.
        ByteString data = ByteString.copyFromUtf8(message);
        PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();

        // Publish a message. Messages are automatically batched.
        ApiFuture<String> future = publisher.publish(pubsubMessage);
        futures.add(future);
      }
    } finally {
      ArrayList<PublishMetadata> metadata = new ArrayList<>();
      List<String> ackIds = ApiFutures.allAsList(futures).get();
      for (String id : ackIds) {
        // Decoded metadata contains partition and offset.
        metadata.add(PublishMetadata.decode(id));
      }
      System.out.println(metadata + "\nPublished " + ackIds.size() + " messages.");

      if (publisher != null) {
        // Shut down the publisher.
        publisher.stopAsync().awaitTerminated();
        System.out.println("Publisher is shut down.");
      }
    }
  }
}

Python

from google.cloud.pubsublite.cloudpubsub import PublisherClient
from google.cloud.pubsublite.types import (
    CloudRegion,
    CloudZone,
    PublishMetadata,
    TopicPath,
)

# TODO(developer):
# project_number = 1122334455
# cloud_region = "us-central1"
# zone_id = "a"
# topic_id = "your-topic-id"
# num_messages = 100

location = CloudZone(CloudRegion(cloud_region), zone_id)
topic_path = TopicPath(project_number, location, topic_id)

# PublisherClient() must be used in a `with` block or have __enter__() called before use.
with PublisherClient() as publisher_client:
    data = "Hello world!"
    api_future = publisher_client.publish(topic_path, data.encode("utf-8"))
    # result() blocks. To resolve API futures asynchronously, use add_done_callback().
    message_id = api_future.result()
    publish_metadata = PublishMetadata.decode(message_id)
    print(
        f"Published a message to partition {publish_metadata.partition.value} and offset {publish_metadata.cursor.offset}."
    )