RabbitMQ初学之一:exchange与queue的绑定

最近公司需要使用RabbitMQ，但我之前一直使用的是ActiveMQ，对RabbitMQ进行了初步的学习，但是还不系统，自己做了一些小测试，怕自己以后忘了

一. 背景

　　拿到代码以后，发现，生产者在向外发送消息时，指定了exchange（交换机）和routing key，但是没有指定queue（队列）也没有将queue（队列）绑定到exchange，刚开始因为不熟悉rabbitMQ，所有不知道怎么回事，后来知道了：消费者在消费消息时，需要声明队列（队列名字随便），并将声明的队列通过routing key绑定到exchange，这样才能接收到数据，因此，生产者方需要将exchange和routing key实现告知消费者方。

二. 代码实例：生产者方指定了exchange（交换机）和routing key，但是不指定queue（队列）也不将queue（队列）绑定到exchange，队列声明和绑定队列到exchange的工作由消费者方完成

　　1. 生产者方

　　　　① 生产者方代码

import java.io.IOException;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
 
public class Producer {
    private final static String QUEUE_NAME = "QUEUE8";  
 
    public static void main(String[] args) throws IOException { 
        
        ConnectionFactory factory = new ConnectionFactory();  
        factory.setHost("localhost");
        factory.setPort(5672);
        factory.setUsername("guest");
        factory.setPassword("guest");
        
        Connection connection = factory.newConnection();  
        Channel channel = connection.createChannel();  
 
        String message = "Hello World!"; 
        
        // 指定exchange和routing key，并发送消息到exchange
        channel.basicPublish("FILETOPIC", "KEY.FILE", null, message.getBytes());  
        System.out.println(" [x] Sent '" + message + "'");  
 
        channel.close();  
        connection.close();  
    }  
}

　　　　② 生产者方代码运行后，可在rabbiteMQ managerment 管理界面看到相应exchange，如下图所示：

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　　2. 消费者方：消费者声明队列，队列名称随便起，并将该队列通过生产者指定的routing key绑定的其指定的exchange上

　　　　① 消费者方代码

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

public class Reqv {
    
    private final static String QUEUE_NAME = "QUEUE8";  
      
    public static void main(String[] argv) throws Exception {  
        
        ConnectionFactory factory = new ConnectionFactory();
        factory.setPort(5672);  
        factory.setUsername("guest");
        factory.setPassword("guest");
        factory.setHost("localhost");
        
        Connection connection = factory.newConnection();  
        Channel channel = connection.createChannel();  
        
        // 声明队列
        channel.queueDeclare(QUEUE_NAME, false, false, false, null);  
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
        
        // 绑定队列到交换机
        channel.queueBind(QUEUE_NAME, "FILETOPIC", "KEY.FILE");
        
        QueueingConsumer consumer = new QueueingConsumer(channel);  
        channel.basicConsume(QUEUE_NAME, true, consumer);  
        while(true){  
            QueueingConsumer.Delivery delivery = consumer.nextDelivery();  
            String message = new String(delivery.getBody(),"UTF-8");  
            System.out.println(" 【[x] Received 】：" + message);  
        }  
    }  
}

　　　　② 运行效果，消费者方代码运行后，在rabbiteMQ managerment 管理界面可以看到声明的队列，并发现该队列已经绑定到了生产者指定的exchange上

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 三. 代码实例：生产者指定exchange和routing key，声明队列并将队列绑定到exchange，消费者只需从生产者绑定的队列消费即可

　　1. 生产者

　　　　① 生产者代码

import java.io.IOException;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
 
public class Producer {
    private final static String QUEUE_NAME = "QUEUE1";  
 
    public static void main(String[] args) throws IOException { 
        
        ConnectionFactory factory = new ConnectionFactory();  
        factory.setHost("localhost");
        factory.setPort(5672);
        factory.setUsername("guest");
        factory.setPassword("guest");
        
        Connection connection = factory.newConnection();  
        Channel channel = connection.createChannel();  
 
        String message = "Hello World!"; 
        
        // 声明队列
        channel.queueDeclare(QUEUE_NAME, true, false, false, null);
        
        // 绑定队列到交换机
        channel.queueBind(QUEUE_NAME, "FILETOPIC", "KEY.FILE");
        
        // 指定exchange和routing key，并发送消息到exchange
        channel.basicPublish("FILETOPIC", "KEY.FILE", null, message.getBytes());  
        System.out.println(" [x] Sent '" + message + "'");  
 
        channel.close();  
        connection.close();  
    }  
}

　　　　② 生产者运行效果：生产者代码运行后，在rabbiteMQ managerment 管理界面可以看到生产者声明的队列，并发现该队列已经绑定到了生产者指定的exchange上，如下图所示：

　　2. 消费者

　　　　① 消费者代码：消费者现在直接消费队列中的消息即可，既不用声明队列，也不用绑定

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

public class Reqv {
    
    private final static String QUEUE_NAME = "QUEUE1";  
      
    public static void main(String[] argv) throws Exception {  
        
        ConnectionFactory factory = new ConnectionFactory();
        factory.setPort(5672);  
        factory.setUsername("guest");
        factory.setPassword("guest");
        factory.setHost("localhost");
        
        Connection connection = factory.newConnection();  
        Channel channel = connection.createChannel();  
        
        QueueingConsumer consumer = new QueueingConsumer(channel);  
        channel.basicConsume(QUEUE_NAME, true, consumer);  
        while(true){  
            QueueingConsumer.Delivery delivery = consumer.nextDelivery();  
            String message = new String(delivery.getBody(),"UTF-8");  
            System.out.println(" 【[x] Received 】：" + message);  
        }  
    }  
}

　　　　② 消费者运行效果：在rabbiteMQ managerment 管理界面可以看到，生产者指定的队列已经有了消费者