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";

publishWithCustomAttributesExample(projectId, topicId);

}

public static void publishWithCustomAttributesExample(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 = "first message";

ByteString data = ByteString.copyFromUtf8(message);

PubsubMessage pubsubMessage =

PubsubMessage.newBuilder()

.setData(data)

.putAllAttributes(ImmutableMap.of("year", "2020", "author", "unknown"))

.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 a message with custom attributes: " + messageId);

} finally {

if (publisher != null) {

// When finished with the publisher, shutdown to free up resources.

publisher.shutdown();

publisher.awaitTermination(1, TimeUnit.MINUTES);

}

}

}