RabbitMQ之交换机 | 易学教程

1. 交换机类型

　　rabbitmq常见有四种交换机类型： direct, topic, fanout, headers.

　　一般headers都不用，工作中用得较多的是fanout,它会将消息推送到所有绑定在此交换机上的队列中，效率也是这几种交换机中最高的。

　　交换机是啥？感觉跟网关差不多，就是路由、转发消息.

　　下面具体说说几种交换机的使用

2. 交换机的使用

2.1 direct 交换机

　　direct: 直连相当于 1 对 1.

　　生产者----> direct exchange ---> queue ----> 消费者

// 生产端代码
public static void main(String[] args) throws Exception {
        
        //1 创建ConnectionFactory
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        //2 创建Connection
        Connection connection = connectionFactory.newConnection();
        //3 创建Channel
        Channel channel = connection.createChannel();  
        //4 声明
        String exchangeName = "direct_exchange";
                // 5. 路由key, 消费端必须与其一致
        String routingKey = "direct.routingKey";
        //5 发送
        
        String msg = "this is direct exchange test... ";
        channel.basicPublish(exchangeName, routingKey , null , msg.getBytes());         
        
    }

// 消费端代码
public static void main(String[] args) throws Exception {
        ConnectionFactory connectionFactory = new ConnectionFactory() ;  
        
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        connectionFactory.setAutomaticRecoveryEnabled(true);
        connectionFactory.setNetworkRecoveryInterval(3000);
        Connection connection = connectionFactory.newConnection();
        
        Channel channel = connection.createChannel();  
        //4 声明交换机名称 ，注意它必须与生产端一致
        String exchangeName = "direct_exchange";
        String exchangeType = "direct";
        // 队列名称随便取，意思意思 ，绑定就行
        String queueName = "direct_queue";
        // 必须与生产端一致
        String routingKey = "direct.routingKey";
        
        //表示声明了一个交换机
        channel.exchangeDeclare(exchangeName, exchangeType, true, false, false, null);
        //表示声明了一个队列
        channel.queueDeclare(queueName, false, false, false, null);
        //建立一个绑定关系:
        channel.queueBind(queueName, exchangeName, routingKey);
        
        //durable 是否持久化消息
        QueueingConsumer consumer = new QueueingConsumer(channel);
        //参数：队列名称、是否自动ACK、Consumer
        channel.basicConsume(queueName, true, consumer);  
        //循环获取消息  
        while(true){  
            //获取消息，如果没有消息，这一步将会一直阻塞  
            Delivery delivery = consumer.nextDelivery();  
            String msg = new String(delivery.getBody());    
            System.out.println("收到消息：" + msg);  
        } 
    }

　　消息只能路由到一个队列中。。。。

2.2 topic 交换机

　　direct 类型的交换机只能一对一的传递消息，而topic类型的交换机就牛逼了，它支持糊糊匹配，啥意思呢？

　　在direct类型的交换机中，生产端和消息端的routingKey必须一样一样的，否则就不能拿到消息。而topic类型就不一样了，譬如：生产端的routingKey是 zheng.qin.feng，消息端的routingKey可以弄成以下这些都行：

　　zheng.#

　　#.feng

　　zheng.qin.*

　　总之，对于topic类型的交换机而言，一切都是看routingKey，如果消息端队列与交换机绑定时routingKey同生产端与交换机绑定的routingKey有一定龌蹉关系，那么消息最终就会投递到该队列中。

　　注意：消息都是存储在队列中的，交换机只会转发消息，不会存储

　　　　　 # ：任意词匹配

　　　　　 * ：单词匹配

    /**
     * 生产端
     */ 
    public static void main(String[] args) throws Exception {
        
        //1 创建ConnectionFactory
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        //2 创建Connection
        Connection connection = connectionFactory.newConnection();
        //3 创建Channel
        Channel channel = connection.createChannel();  
        //4 声明
        String exchangeName = "topic_exchange";
        String routingKey1 = "user.mmp";
        String routingKey2 = "user.exchange";
        String routingKey3 = "user.test";
        //5 发送
        String msg = "abc lfkdfjdlfjdlfkdlkfdlf";
        channel.basicPublish(exchangeName, routingKey1 , null , msg.getBytes()); 
        channel.basicPublish(exchangeName, routingKey2 , null , msg.getBytes());     
        channel.basicPublish(exchangeName, routingKey3 , null , msg.getBytes()); 
        channel.close();  
        connection.close();  
    }

/**
     *  消费者
     */
    public static void main(String[] args) throws Exception {
        
        
        ConnectionFactory connectionFactory = new ConnectionFactory() ;  
        
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        connectionFactory.setAutomaticRecoveryEnabled(true);
        connectionFactory.setNetworkRecoveryInterval(3000);
        Connection connection = connectionFactory.newConnection();
        
        Channel channel = connection.createChannel();  
        //4 声明
        String exchangeName = "topic_exchange";
        String exchangeType = "topic";
        String queueName = "topic_queue";
        String routingKey = "user.*";
        // 1 声明交换机 
        channel.exchangeDeclare(exchangeName, exchangeType, true, false, false, null);
        // 2 声明队列
        channel.queueDeclare(queueName, false, false, false, null);
        // 3 建立交换机和队列的绑定关系:
        channel.queueBind(queueName, exchangeName, routingKey);
        
        //durable 是否持久化消息
        QueueingConsumer consumer = new QueueingConsumer(channel);
        //参数：队列名称、是否自动ACK、Consumer
        channel.basicConsume(queueName, true, consumer);  
        //循环获取消息  
        while(true){  
            //获取消息，如果没有消息，这一步将会一直阻塞  
            Delivery delivery = consumer.nextDelivery();  
            String msg = new String(delivery.getBody());    
            System.out.println("收到消息：" + msg);  
        } 
    }

　　消息根据routingKey来决定路由到哪些队列中。。。。。

2.3 fanout交换机

　　这个没啥说的，跟routingKey木有关系，只要是绑定到fanout类型交换机上的队列，都能拿到消息。

　　简单的讲：就是1 对多的关系，，比 topic类型的交换机还是滥情，毕竟topic交换机看不上丑女，fanout呢，是个女人都行。

// 生产者
    public static void main(String[] args) throws Exception {
        
        //1 创建ConnectionFactory
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        //2 创建Connection
        Connection connection = connectionFactory.newConnection();
        //3 创建Channel
        Channel channel = connection.createChannel();  
        //4 声明
        String exchangeName = "test_fanout_exchange";
        //5 发送
        for(int i = 0; i < 10; i ++) {
            String msg = "hahahah";
            channel.basicPublish(exchangeName, "", null , msg.getBytes());             
        }
        channel.close();  
        connection.close();  
    }

// 消息者
    public static void main(String[] args) throws Exception {
        
        ConnectionFactory connectionFactory = new ConnectionFactory() ;  
        
        connectionFactory.setHost("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        connectionFactory.setAutomaticRecoveryEnabled(true);
        connectionFactory.setNetworkRecoveryInterval(3000);
        Connection connection = connectionFactory.newConnection();
        
        Channel channel = connection.createChannel();  
        //4 声明
        String exchangeName = "fanout_exchange";
        String exchangeType = "fanout";
        String queueName = "test_fanout_queue";
        String routingKey = "";    //不设置路由键，设置也可以，无所谓呀， 反正都行
        channel.exchangeDeclare(exchangeName, exchangeType, true, false, false, null);
        channel.queueDeclare(queueName, false, false, false, null);
        channel.queueBind(queueName, exchangeName, routingKey);
        
        //durable 是否持久化消息
        QueueingConsumer consumer = new QueueingConsumer(channel);
        //参数：队列名称、是否自动ACK、Consumer
        channel.basicConsume(queueName, true, consumer); 
        //循环获取消息  
        while(true){  
            Delivery delivery = consumer.nextDelivery();  
            String msg = new String(delivery.getBody());    
            System.out.println("收到消息：" + msg);  
        } 
    }

　　尼玛，只要绑定到此交换机上的队列，都会被路由。。。。

来源：oschina

链接：https://my.oschina.net/u/4408758/blog/3387818

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