A queue characteristic pattern

Clients include producers and consumers
Messages in the queue can only be consumed by a consumer
Consumers can consume messages in the queue at any time

Second, the creation process

1. Create a connection Connection
2. Create a session the Session
3. to create additional (MessageProducer, MessageConsumer, Destination, TextMessage ) by the Session
4. MessageProducer the producers and consumers will point to destination MessageConsumer the Destination
5. The producer sends a message to the target TextMessage the send ()
6. set consumers listener, listen for messages.

Third, code implementation

1. Create a Maven project

<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.jms</groupId>
    <artifactId>jms-test</artifactId>
    <version>1.0-SNAPSHOT</version>
    
    <!-- activemq依赖 -->
    <dependencies>
        <dependency>
            <groupId>org.apache.activemq</groupId>
            <artifactId>activemq-all</artifactId>
            <version>5.9.0</version>
        </dependency>
    </dependencies>

</project>

2. 生产者 AppProducer.java

public class AppProducer {
    private static final String url = "tcp://127.0.0.1:61616";
    private static final String queueName = "queue-test";

    public static void main(String[] args) throws JMSException {
        //1.创建ConnectionFactory
        ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory(url);
        //2.创建Connection
        Connection connection = connectionFactory.createConnection();
        //3.启动连接
        connection.start();
        //4.创建会话
        Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        //5.创建一个目标
        Destination destination = session.createQueue(queueName);
        //6.创建一个生产者
        MessageProducer producer = session.createProducer(destination);
        for (int i = 0; i < 10; i++) {
            //7.创建消息
            TextMessage textMessage = session.createTextMessage("test" + i);
            //8.发布消息
            producer.send(textMessage);

            System.out.println("发送消息"+textMessage.getText());
        }

        //9.关闭连接
        connection.close();

    }
}

3. 消费者 AppConsumer.java

消费者的连接Connection是不能关闭的，因为消息的接收是异步的，会导致消息不能被消费。

public class AppConsumer {
    private static final String url = "tcp://127.0.0.1:61616";
    private static final String queueName = "queue-test";

    public static void main(String[] args) throws JMSException {
        //1. 创建ConnectionFactory
        ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory(url);
        //2. 创建Connection
        Connection connection = connectionFactory.createConnection();
        //3. 启动连接
        connection.start();
        //4. 创建会话
        Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        //5. 创建一个目标
        Destination destination = session.createQueue(queueName);
        //6. 创建一个消费者
        MessageConsumer consumer = session.createConsumer(destination);
        //7. 创建一个监听器
        consumer.setMessageListener(new MessageListener() {
            public void onMessage(Message message) {
                try {
                    System.out.println("接收消息  = [" + ((TextMessage) message).getText() + "]");
                } catch (JMSException e) {
                    e.printStackTrace();
                }
            }
        });

        //8.关闭连接（消费者的连接不允许关闭的，因为消息的接收是异步的，会导致消息不能被消费）
        //connection.close();
    }
}

四、运行查看

1. 运行生产者 AppProducer

运行AppProducer.java后会发现队列中添加了10条消息，如下图：

2. 开启消费者 AppConsumer

运行AppConsumer.java后会发现队列中的10条消息被消费了，如下图：

3.开启两个消费者后，运行生产者

会发现生产者发送的10个消息，被两个消费者平分了。
AppConsumer1

接收消息  = [test1]
接收消息  = [test3]
接收消息  = [test5]
接收消息  = [test7]
接收消息  = [test9]

AppConsumer2

接收消息  = [test0]
接收消息  = [test2]
接收消息  = [test4]
接收消息  = [test6]
接收消息  = [test8]

五、队列模式和主题模式的区别

是否需要提前订阅
队列模式：消费者不需要提前订阅也可以消费消息
主题模式：只有提前进行订阅的消费者才能成功消费消息
How multiple consumers assignment message
queue mode: only average consumer news, the consumption of other consumer message can not be repeated by other consumer spending
theme: Each subscriber can consume theme in each message

ActiveMQ message patterns - Mode queue (Queue)