RabbitMQ usage scenario exercise: topic Topic (5)

• Topic Forwarder (Topic)

     The functions of Topic repeaters include fanout and direct type repeaters. The special feature is that the routingkey can use wildcards * and # when binding the repeater to the queue. Using * is equivalent to fanout, and not using wildcards is equivalent to direct. Otherwise, it is a fuzzy match, and all queues on the match can receive the message

• Points to Note

topic forwarder :

channel.exchangeDeclare("topic_logs", "topic");
channel.basicPublish("topic_logs", severity , null, SerializationUtils.serialize(object));

The binding between the forwarder and the queue (specifying the routingkey), the difference from the direct forwarder is that the routingkey can use *, # wildcard fuzzy matching :

//Specify routingkey when binding temporary queue and forwarder
 channel.queueBind(queueName, "topic_logs", severity);

• message sending class

package com.demo.mq.rabbitmq.example05;

import java.io.IOException;
import java.io.Serializable;
import java.util.Random;

import org.apache.commons.lang3.SerializationUtils;

import com.demo.mq.rabbitmq.MqManager;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;

/**
 * Send message class
 * @author sheungxin
 *
 */
public class Send{

	/**
	 * Send message, topic repeater, fuzzy matching corresponding queue by routingKey
	 * @param object message body
	 * @throws IOException
	 */
	public static void sendAToB(Serializable object) throws Exception{
		Connection conn=MqManager.newConnection();
		Channel channel=conn.createChannel();
		channel.exchangeDeclare("topic_logs", "topic");
		for(int i=0;i<9;i++){
			String severity=getSeverity();
			channel.basicPublish("topic_logs", severity , null, SerializationUtils.serialize(object));
			System.out.println(severity+":Send '"+object+"'");
		}
		channel.close();
		conn.close();
	}
	
	private static String getSeverity(){
		String[] severities=new String[]{"kernal.info","kernal.warn","kernal.error","auth.info","auth.warn","auth.error"};
		Random random=new Random();
		return severities[random.nextInt(6)];
	}
	
	public static void main(String[] args) throws Exception {
		sendAToB("Hello World !");
	}
}

• message receiving class

package com.demo.mq.rabbitmq.example05;

import java.io.IOException;
import java.util.Random;

import org.apache.commons.lang3.SerializationUtils;

import com.demo.mq.rabbitmq.MqManager;
import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.Consumer;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;

/**
 * Receive message class
 * @author sheungxin
 *
 */
public class Recv {
	
	/**
	 * Used to receive messages, create a temporary queue, bind to the repeater topic, and vaguely specify routingKey
	 * @param queue
	 * @throws Exception
	 */
	public static void recvAToB() throws Exception{
		Connection conn=MqManager.newConnection();
		Channel channel=conn.createChannel();
		channel.exchangeDeclare("topic_logs", "topic");
		//create a temporary queue
		String queueName=channel.queueDeclare().getQueue();
		//Bind temporary queue and forwarder logs
		String severity=getSeverity();
		channel.queueBind(queueName, "topic_logs", severity);
		System.out.println(severity+":Received ...");
		Consumer consumer=new DefaultConsumer(channel){
			@Override
			public void handleDelivery(String consumerTag,Envelope envelope,AMQP.BasicProperties properties,byte[] body) throws IOException{
				String mes=SerializationUtils.deserialize(body);
				System.out.println(envelope.getRoutingKey()+":Received :'"+mes+"' done");
			}
		};
		//Turn off the automatic response mechanism, which is enabled by default; at this time, you need to manually perform the response
		channel.basicConsume(queueName, true, consumer);
	}
	
	private static String getSeverity(){
		String[] severities=new String[]{"*.info","*.warn","*.error","kernal.*","auth.*"};
		Random random=new Random();
		return severities[random.nextInt(5)];
	}
	
	public static void main(String[] args) throws Exception {
		recvAToB ();
	}

}