Google Pub/Sub Java示例 [英] Google Pub/Sub Java examples
问题描述
我找不到使用Java从pub/sub中读取消息的方法.
I'm not able to find a way to read messages from pub/sub using java.
我在pom中使用了这个maven依赖项
I'm using this maven dependency in my pom
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-pubsub</artifactId>
<version>0.17.2-alpha</version>
</dependency>
我实现了这个主要方法来创建新主题:
I implemented this main method to create a new topic:
public static void main(String... args) throws Exception {
// Your Google Cloud Platform project ID
String projectId = ServiceOptions.getDefaultProjectId();
// Your topic ID
String topicId = "my-new-topic-1";
// Create a new topic
TopicName topic = TopicName.create(projectId, topicId);
try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
topicAdminClient.createTopic(topic);
}
}
上面的代码运行良好,确实,我可以看到我使用google cloud控制台创建的新主题.
The above code works well and, indeed, I can see the new topic I created using the google cloud console.
我实现了以下主要方法来向我的主题写消息:
I implemented the following main method to write a message to my topic:
public static void main(String a[]) throws InterruptedException, ExecutionException{
String projectId = ServiceOptions.getDefaultProjectId();
String topicId = "my-new-topic-1";
String payload = "Hellooooo!!!";
PubsubMessage pubsubMessage =
PubsubMessage.newBuilder().setData(ByteString.copyFromUtf8(payload)).build();
TopicName topic = TopicName.create(projectId, topicId);
Publisher publisher;
try {
publisher = Publisher.defaultBuilder(
topic)
.build();
publisher.publish(pubsubMessage);
System.out.println("Sent!");
} catch (IOException e) {
System.out.println("Not Sended!");
e.printStackTrace();
}
}
现在,我无法验证此消息是否真的发送了. 我想使用对我的主题的订阅来实现消息阅读器. 有人可以向我展示一个有关从主题中读取消息的正确且有效的Java示例吗?
Now I'm not able to verify if this message was really sent. I would like to implement a message reader using a subscription to my topic. Could someone show me a correct and working java example about reading messages from a topic?
有人可以帮助我吗? 预先感谢!
Anyone can help me? Thanks in advance!
推荐答案
以下是使用Google云客户端库的版本.
Here is the version using the google cloud client libraries.
package com.techm.data.client;
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.ProjectSubscriptionName;
import com.google.pubsub.v1.ProjectTopicName;
import com.google.pubsub.v1.PubsubMessage;
import com.google.pubsub.v1.PushConfig;
/**
* 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 {
private static String projectId = "projectId";
private static String topicId = "topicName";
private static String subscriptionId = "subscriptionName";
public static void createSubscription() throws Exception {
ProjectTopicName topic = ProjectTopicName.of(projectId, topicId);
ProjectSubscriptionName subscription = ProjectSubscriptionName.of(projectId, subscriptionId);
try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
subscriptionAdminClient.createSubscription(subscription, topic, PushConfig.getDefaultInstance(), 0);
}
}
public static void main(String... args) throws Exception {
ProjectSubscriptionName subscription = ProjectSubscriptionName.of(projectId, subscriptionId);
createSubscription();
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();
}
}
}
}
这对我来说很好.
这篇关于Google Pub/Sub Java示例的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!