com.google.cloud.examples.pubsub.snippets.CreateSubscriptionAndConsumeMessages.java Source code

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/*
 * Copyright 2016 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.cloud.examples.pubsub.snippets;

import com.google.cloud.pubsub.v1.AckReplyConsumer;
import com.google.cloud.pubsub.v1.MessageReceiver;
import com.google.cloud.pubsub.v1.Subscriber;
import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.pubsub.v1.PubsubMessage;
import com.google.pubsub.v1.PushConfig;
import com.google.pubsub.v1.SubscriptionName;
import com.google.pubsub.v1.TopicName;

/**
 * A snippet for Google Cloud Pub/Sub showing how to create a Pub/Sub pull subscription and
 * asynchronously pull messages from it.
 */
public class CreateSubscriptionAndConsumeMessages {

    public static void main(String... args) throws Exception {
        TopicName topic = TopicName.of("my-project-id", "my-topic-id");
        SubscriptionName subscription = SubscriptionName.of("my-project-id", "my-subscription-id");

        try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
            subscriptionAdminClient.createSubscription(subscription, topic, PushConfig.getDefaultInstance(), 0);
        }

        MessageReceiver receiver = new MessageReceiver() {
            @Override
            public void receiveMessage(PubsubMessage message, AckReplyConsumer consumer) {
                System.out.println("Received message: " + message.getData().toStringUtf8());
                consumer.ack();
            }
        };
        Subscriber subscriber = null;
        try {
            subscriber = Subscriber.newBuilder(subscription, receiver).build();
            subscriber.addListener(new Subscriber.Listener() {
                @Override
                public void failed(Subscriber.State from, Throwable failure) {
                    // Handle failure. This is called when the Subscriber encountered a fatal error and is shutting down.
                    System.err.println(failure);
                }
            }, MoreExecutors.directExecutor());
            subscriber.startAsync().awaitRunning();

            // In this example, we will pull messages for one minute (60,000ms) then stop.
            // In a real application, this sleep-then-stop is not necessary.
            // Simply call stopAsync().awaitTerminated() when the server is shutting down, etc.
            Thread.sleep(60000);
        } finally {
            if (subscriber != null) {
                subscriber.stopAsync().awaitTerminated();
            }
        }
    }
}