RabbitMQ初學之一:exchange與queue的綁定

最近公司需要使用RabbitMQ，但我之前一直使用的是ActiveMQ，對RabbitMQ進行了初步的學習，但是還不系統，自己做了一些小測試，怕自己以后忘了

一. 背景

　　拿到代碼以后，發現，生產者在向外發送消息時，指定了exchange（交換機）和routing key，但是沒有指定queue（隊列）也沒有將queue（隊列）綁定到exchange，剛開始因為不熟悉rabbitMQ，所有不知道怎么回事，后來知道了：消費者在消費消息時，需要聲明隊列（隊列名字隨便），並將聲明的隊列通過routing key綁定到exchange，這樣才能接收到數據，因此，生產者方需要將exchange和routing key實現告知消費者方。

二. 代碼實例：生產者方指定了exchange（交換機）和routing key，但是不指定queue（隊列）也不將queue（隊列）綁定到exchange，隊列聲明和綁定隊列到exchange的工作由消費者方完成

　　1. 生產者方

　　　　① 生產者方代碼

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，並發送消息到exchange
        channel.basicPublish("FILETOPIC", "KEY.FILE", null, message.getBytes());  
        System.out.println(" [x] Sent '" + message + "'");  
 
        channel.close();  
        connection.close();  
    }  
}

　　　　② 生產者方代碼運行后，可在rabbiteMQ managerment 管理界面看到相應exchange，如下圖所示：

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　　2. 消費者方：消費者聲明隊列，隊列名稱隨便起，並將該隊列通過生產者指定的routing key綁定的其指定的exchange上

　　　　① 消費者方代碼

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();  
        
        // 聲明隊列
        channel.queueDeclare(QUEUE_NAME, false, false, false, null);  
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
        
        // 綁定隊列到交換機
        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 運行效果，消費者方代碼運行后，在rabbiteMQ managerment 管理界面可以看到聲明的隊列，並發現該隊列已經綁定到了生產者指定的exchange上

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 三. 代碼實例：生產者指定exchange和routing key，聲明隊列並將隊列綁定到exchange，消費者只需從生產者綁定的隊列消費即可

　　1. 生產者

　　　　① 生產者代碼

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!"; 
        
        // 聲明隊列
        channel.queueDeclare(QUEUE_NAME, true, false, false, null);
        
        // 綁定隊列到交換機
        channel.queueBind(QUEUE_NAME, "FILETOPIC", "KEY.FILE");
        
        // 指定exchange和routing key，並發送消息到exchange
        channel.basicPublish("FILETOPIC", "KEY.FILE", null, message.getBytes());  
        System.out.println(" [x] Sent '" + message + "'");  
 
        channel.close();  
        connection.close();  
    }  
}

　　　　② 生產者運行效果：生產者代碼運行后，在rabbiteMQ managerment 管理界面可以看到生產者聲明的隊列，並發現該隊列已經綁定到了生產者指定的exchange上，如下圖所示：

　　2. 消費者

　　　　① 消費者代碼：消費者現在直接消費隊列中的消息即可，既不用聲明隊列，也不用綁定

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 消費者運行效果：在rabbiteMQ managerment 管理界面可以看到，生產者指定的隊列已經有了消費者