ActiveMQ_015：Exclusive Consumers 使用例子

环境：OS X EI Capitan 10.11.3 + ActiveMQ 5.13.0

Exclusive Consumers 是一个Queue的排他消费者，就是同一时刻只能有一个消费者消费Queue中的消息。
当这个消费者退出后，其它消费者可以争抢这个唯一的消费名额。

1. Queue_Exclusive_Consumer_AutoAck_Sync.java

package com.travelsky.activemq;

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.MessageConsumer;
import javax.jms.Session;
import javax.jms.TextMessage;
import org.apache.activemq.ActiveMQConnectionFactory;

public class Queue_Exclusive_Consumer_AutoAck_Sync {

    public static void main(String[] args) {

        // ConnectionFactory：连接工厂，JMS用它创建连接
        ConnectionFactory connectionFactory;
        // Connection：JMS客户端到JMS Provider的连接
        Connection connection = null;
        // Session：一个发送或接收消息的线程
        Session session;
        // Destination：消息的目的地;消息发送给谁.
        Destination destination;
        // MessageConsumer：消息消费者
        MessageConsumer consumer;

        connectionFactory = new ActiveMQConnectionFactory(
                "admin",
                "admin",
                "failover:(tcp://127.0.0.1:61616)");
           
        try {
            connection = connectionFactory.createConnection();
            connection.start();
            session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
            destination = session.createQueue("FirstQueue?consumer.exclusive=true&consumer.priority=10");
            consumer = session.createConsumer(destination);
            while (true) {
                TextMessage message = (TextMessage) consumer.receive(100000);
                if (null != message) {
                    System.out.println("收到消息" + message.getText());
                } else {
                    break;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (null != connection) {
                    connection.close();
                }
            } catch (Throwable ignore) {
            }
        }
    }
}

consumer.priority的数字越高，表明优先级越大。

参考文献：
1. http://marcelojabali.blogspot.com/2011/11/preserving-message-order-with-apache.html