RabbitMQ 入门

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RabbitMQ 入门

随着业务的增多, 系统中的服务越来越多, 这就面临系统中服务调用紊乱的问题. 尤其在最近需要做一个任务调度的系统, 在三番思考之后, 决定采用RabbitMQ的消息队列实现任务调度问题.以下简称RMQ

1.下载安装RMQ

下载地址:http://www.rabbitmq.com/download.html

笔者使用的是ubuntu系统, 下载并安装完后, 进入官方的使用文档http://www.rabbitmq.com/install-debian.html

下载安装后, RMQ默认是已经启动的, 当然我们也可以手动进行启动关闭操作,具体命令:

rabbitmqctl 默认产生详细输出。通过”-q”标示可选择安静模式。
rabbitmqctl -q status
应用和集群管理
1.停止RabbitMQ应用，关闭节点
# rabbitmqctl stop
2.停止RabbitMQ应用
# rabbitmqctl stop_app
3.启动RabbitMQ应用
# rabbitmqctl start_app
4.显示RabbitMQ中间件各种信息
# rabbitmqctl status
5.重置RabbitMQ节点
# rabbitmqctl reset
# rabbitmqctl force_reset

2.Helloword

下载依赖的jar包:http://www.rabbitmq.com/java-client.html

RabbitMQ要实现的是一个典型的生产者消费者案例. 生产者向消息队列不断发送消息, 众多消费者从消息队列中取消息. RabbitMQ的存在, 简单而言就是解决消息队列中的存取问题.

开始码代码.以下是生产者代码:

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package cn.iyowei.mq.greeting;
 
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
 
/**
 *生产者,每800ms发送一条消息给消息队列
 */
public class MQProducer {
    private static final String QUEUE_NAME = "greeting";
 
    public static void main(String[] argv) throws java.io.IOException, InterruptedException {
        /**
         * 创建连接连接到MabbitMQ
         */
        String producerName = "producer-[" + new Random().nextInt(9) + "]";
        ConnectionFactory factory = new ConnectionFactory();
        // 设置MabbitMQ所在主机ip或者主机名
        factory.setHost("localhost");
        // 创建一个连接
        Connection connection = factory.newConnection();
        // 创建一个频道
        Channel channel = connection.createChannel();
        // 指定一个队列
        channel.queueDeclare(QUEUE_NAME, false, false, false, null);
        // 发送的消息
        String message;
 
        // 往队列中发300条消息
        for (int i = 0; i < 300; i++) {
            message = "hello world! " + i;
            channel.basicPublish("", QUEUE_NAME, null, message.getBytes());
            Thread.sleep(800); // 等待800ms
            System.out.println(producerName + " Sent '" + message + "'");
        }
 
        // 关闭频道和连接
        channel.close();
        connection.close();
    }
}

生产者主要负责每800ms发送一条消息给消息队列.

以下是消费者代码:

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packagecn.iyowei.mq.greeting;
 
importcom.rabbitmq.client.Channel;
importcom.rabbitmq.client.Connection;
importcom.rabbitmq.client.ConnectionFactory;
importcom.rabbitmq.client.QueueingConsumer;
 
/**
* 消费者,可以启动多个进行消费
*/
publicclassMQConsumer{
    // 队列名称
    privatestaticfinalStringQUEUE_NAME="greeting";
 
    publicstaticvoidmain(String[]argv)throwsjava.io.IOException,
            java.lang.InterruptedException{
        StringconsumerName=" [consumer-"+newRandom().nextInt(9)+"]";
        // 打开连接和创建频道，与发送端一样
        ConnectionFactoryfactory=newConnectionFactory();
        factory.setHost("localhost");
        Connectionconnection=factory.newConnection();
        Channelchannel=connection.createChannel();
        // 声明队列，主要为了防止消息接收者先运行此程序，队列还不存在时创建队列。
        channel.queueDeclare(QUEUE_NAME,false,false,false,null);
        System.out.println(consumerName+" Waiting for messages. To exit press CTRL+C");
 
        // 创建队列消费者
        QueueingConsumerconsumer=newQueueingConsumer(channel);
        // 指定消费队列
        channel.basicConsume(QUEUE_NAME,true,consumer);
        while(true)
        {
            // nextDelivery是一个阻塞方法（内部实现其实是阻塞队列的take方法）
            QueueingConsumer.Deliverydelivery=consumer.nextDelivery();
            Stringmessage=newString(delivery.getBody());
            System.out.println(consumerName+" Received '"+message+"'");
        }
 
    }
}

消费者主要负责从队列从拉取消息.

注意到代码中给每个生产者和消费者这使用random命名, 旨在同时启动多个生产者和消费者, 以观察执行效果.

笔者开了一个生产者,三个消费者,生产者的log大致如:

producer-[1] Sent ‘hello world! 0′
producer-[1] Sent ‘hello world! 1′
producer-[1] Sent ‘hello world! 2′
producer-[1] Sent ‘hello world! 3′
producer-[1] Sent ‘hello world! 4′
producer-[1] Sent ‘hello world! 5′
producer-[1] Sent ‘hello world! 6′
producer-[1] Sent ‘hello world! 7′
producer-[1] Sent ‘hello world! 8′

而消费者1的log:

[consumer-1] Waiting for messages. To exit press CTRL+C
[consumer-1] Received ‘hello world! 0′
[consumer-1] Received ‘hello world! 3′
[consumer-1] Received ‘hello world! 6′

消费者2的log:

[consumer-2] Waiting for messages. To exit press CTRL+C
[consumer-2] Received ‘hello world! 1′
[consumer-2] Received ‘hello world! 4′
[consumer-2] Received ‘hello world! 7′

消费者3的log:

[consumer-3] Waiting for messages. To exit press CTRL+C
[consumer-3] Received ‘hello world! 2′
[consumer-3] Received ‘hello world! 5′
[consumer-3] Received ‘hello world! 8′

由上面的结果可以简单的推断, 消息队列向消费者发送消息的时候是从消费者1-消费者n轮流发送的.

下一篇:RabbitMQ (二) 命令初尝

javaRabbitMQ后端服务器消息队列

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