（转）RabbitMQ学习之主题topic（java）

http://blog.csdn.net/zhu_tianwei/article/details/40887775

参考：http://blog.csdn.NET/lmj623565791/article/details/37706355

direct类型的消息通过绑定键转发到队列，但是存在一些局限性：它不能够基于多重条件进行路由选择，有可能希望不仅根据日志的级别而且想根据日志的来源进行订阅，这就需要主题类型的转发器来实现。

发往主题类型的转发器的消息不能随意的设置选择键（routing_key），必须是由点隔开的一系列的标识符组成。标识符可以是任何东西，但是一般都与消息的某些特性相关。一些合法的选择键的例子："stock.usd.nyse", "nyse.vmw","quick.orange.rabbit".你可以定义任何数量的标识符，上限为255个字节。
绑定键和选择键的形式一样。主题类型的转发器背后的逻辑和直接类型的转发器很类似：一个附带特殊的选择键将会被转发到绑定键与之匹配的队列中。需要注意的是：关于绑定键有两种特殊的情况。
*可以匹配一个标识符。
#可以匹配0个或多个标识符。

1.发送日志消息SendLogTopic，发送4个消息绑定不同的绑定键， "kernal.info", "cron.warning",  "auth.info", "kernel.critical" 

package cn.slimsmart.rabbitmq.demo.topic;

import java.util.UUID;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

//发送消息端
public class SendLogTopic {
    private static final String EXCHANGE_NAME = "topic_logs";
    public static void main(String[] args) throws Exception {
        // 创建连接和频道
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("192.168.101.174");
    factory.setUsername("admin");
        factory.setPassword("admin");
        factory.setPort(AMQP.PROTOCOL.PORT);
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        // 声明转发器
        channel.exchangeDeclare(EXCHANGE_NAME, "topic");
        //定义绑定键
        String[] routing_keys = new String[] { "kernal.info", "cron.warning",
                "auth.info", "kernel.critical" };
        for (String routing_key : routing_keys)
        {
            //发送4条不同绑定键的消息
            String msg = UUID.randomUUID().toString();
            channel.basicPublish(EXCHANGE_NAME, routing_key, null, msg
                    .getBytes());
            System.out.println(" [x] Sent routingKey = "+routing_key+" ,msg = " + msg + ".");
        }

        channel.close();
        connection.close();
    }

}

2.定义接收kernel.*消息的消费者

package cn.slimsmart.rabbitmq.demo.topic;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.QueueingConsumer;

//接收kernel.*消息
public class ReceiveLogsTopicForKernel {
    private static final String EXCHANGE_NAME = "topic_logs";
    public static void main(String[] args) throws Exception {
        // 创建连接和频道
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("192.168.101.174");
    factory.setUsername("admin");
       factory.setPassword("admin");
    factory.setPort(AMQP.PROTOCOL.PORT);
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        // 声明转发器
        channel.exchangeDeclare(EXCHANGE_NAME, "topic");
        // 随机生成一个队列
        String queueName = channel.queueDeclare().getQueue();

        //接收所有与kernel相关的消息
        channel.queueBind(queueName, EXCHANGE_NAME, "kernel.*");

        System.out.println(" [*] Waiting for messages about kernel. To exit press CTRL+C");

        QueueingConsumer consumer = new QueueingConsumer(channel);
        channel.basicConsume(queueName, true, consumer);

        while (true)
        {
            QueueingConsumer.Delivery delivery = consumer.nextDelivery();
            String message = new String(delivery.getBody());
            String routingKey = delivery.getEnvelope().getRoutingKey();

            System.out.println(" [x] Received routingKey = " + routingKey
                    + ",msg = " + message + ".");
        }
    }
}

3.接收*.critical消息消费者

package cn.slimsmart.rabbitmq.demo.topic;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.QueueingConsumer;

//接收*.critical消息
public class ReceiveLogsTopicForCritical {

     private static final String EXCHANGE_NAME = "topic_logs";

    public static void main(String[] args) throws Exception {
        // 创建连接和频道
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("192.168.101.174");
    factory.setUsername("admin");
        factory.setPassword("admin");
    factory.setPort(AMQP.PROTOCOL.PORT);
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        // 声明转发器
        channel.exchangeDeclare(EXCHANGE_NAME, "topic");
        // 随机生成一个队列
        String queueName = channel.queueDeclare().getQueue();
        // 接收所有与kernel相关的消息
        channel.queueBind(queueName, EXCHANGE_NAME, "*.critical");

        System.out
                .println(" [*] Waiting for critical messages. To exit press CTRL+C");

        QueueingConsumer consumer = new QueueingConsumer(channel);
        channel.basicConsume(queueName, true, consumer);

        while (true)
        {
            QueueingConsumer.Delivery delivery = consumer.nextDelivery();
            String message = new String(delivery.getBody());
            String routingKey = delivery.getEnvelope().getRoutingKey();

            System.out.println(" [x] Received routingKey = " + routingKey
                    + ",msg = " + message + ".");
        }
    }

}

启动2个消费者，再启动发送4类消息生产者。观察接收到的消息，都收到对应的消息。可以看出使用topic类型的转发器，成功实现了多重条件选择的订阅。