java - 在 JMS 队列上发布消息？

Question

我是 JMS 新手，正在查看 Active MQ Hello world 的示例。假设我每次进入时都会有一个场景在数据库中的员工表下，我必须将消息放入队列中。这是 hello world 示例中的生产者代码片段

public static class HelloWorldProducer  {
        public void createMessageOnQueue() {
            try {
                // Create a ConnectionFactory
                ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory("vm://localhost");

                // Create a Connection
                Connection connection = connectionFactory.createConnection();
                connection.start();

                // Create a Session
                Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);

                // Create the destination (Topic or Queue)
                Destination destination = session.createQueue("TEST.FOO");

                // Create a MessageProducer from the Session to the Topic or Queue
                MessageProducer producer = session.createProducer(destination);
                producer.setDeliveryMode(DeliveryMode.NON_PERSISTENT);

                // Create a messages
                String text = "Hello world! From: " + Thread.currentThread().getName() + " : " + this.hashCode();
                TextMessage message = session.createTextMessage(text);

                // Tell the producer to send the message
                System.out.println("Sent message: "+ message.hashCode() + " : " + Thread.currentThread().getName());
                producer.send(message);

                // Clean up
                session.close();
                connection.close();
            }
            catch (Exception e) {
                System.out.println("Caught: " + e);
                e.printStackTrace();
            }
        }
    }

现在我的问题是，如果我关闭连接和 session ，它也会关闭队列吗？如果是，如果消息还没有被消费会发生什么？

第二个问题是，如果我需要在同一个队列(即“TEST.FOO”)上第二次发布消息，我是否需要第二次调用 createMessageOnQueue 方法。如果是，它不会使用 session.createQueue("TEST.FOO") 创建新队列吗？

Answer 1

Now my question is if i close the connection and session, will it close the queue also? If yes,what will happen if message has not been consumed yet?

消息仍将在队列中。没有“关闭队列”这样的事情。

Second question is if i need to publish the message on same queue(i.e "TEST.FOO") second time , do i need to call createMessageOnQueue method second time. If yes, will it not create new queue with session.createQueue("TEST.FOO")?

session.createQueue("TEST.FOO") 不一定创建队列，它只是获取对现有队列的引用。

session 的javadoc#createQueue()

Note that this method simply creates an object that encapsulates the name of a topic. It does not create the physical topic in the JMS provider. JMS does not provide a method to create the physical topic, since this would be specific to a given JMS provider. Creating a physical topic is provider-specific and is typically an administrative task performed by an administrator, though some providers may create them automatically when needed.