rabbitmq(5)订阅模式

rabbitmq

1、模型

一个生产者绑定一个交换机，每个消费者绑定一个队列。生产者将消息通过交换器分发给所有在线的消费者。
交换机没有消息存储的能力，只能向当前在线的消费者发送消息。因此未接收到消息的消费者，即使重新连接rabbitmq也无法获取到已发送的消息

这里写图片描述

订阅模式与普通队列的区别：

  1. 普通队列中生产者发送的消息只能有一个消费者接受到；订阅模式中生产者发送的消息会被所有在线的消费者接收到；
  2. 普通队列中生产者消息会被储存，即使消费者没有成功接受到消息，重新上线后也可以重新收到该消息；订阅模式中生产者消息不会被储存；

    2、代码

    2.1、生产者

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    private final static String EXCHANGE_NAME = "test_exchange";

    @Test
    public void testSend() throws Exception {
    	ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("192.168.1.7");
        factory.setUsername("root");
        factory.setPassword("123456");
        
    	Connection connection = factory.newConnection();
    	Channel channel = connection.createChannel();
    	
    	/* 
    	 * 申明交换机, fanout:分发
    	 * 交换机没有消息存储的能力,只能向当前在线的消费者发送消息
    	 * 未接收到消息的消费者,即使重新连接rabbitmq也无法获取到已发送的消息
    	 */
    	channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
    	
    	String message = "Hello world";
    	channel.basicPublish(EXCHANGE_NAME, "", null, message.getBytes());
    	System.out.println(" [1] Sent '" + message + "'");
    	
    	channel.close();
    	connection.close();
    }

2.2、消费者1

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private final static String EXCHANGE_NAME = "test_exchange";

public static void main(String[] args) throws Exception {
	ConnectionFactory factory = new ConnectionFactory();
    factory.setHost("192.168.1.7");
    factory.setUsername("root");
    factory.setPassword("123456");
    
	Connection connection = factory.newConnection();
	final Channel channel = connection.createChannel();

	channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
	String queueName = channel.queueDeclare().getQueue();
	// 绑定队列到交换机转发器
	channel.queueBind(queueName, EXCHANGE_NAME, "");
	
	System.out.println(" [1] Waiting for messages. To exit press CTRL+C");
	Consumer consumer = new DefaultConsumer(channel) {
		@Override
		public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties,
				byte[] body) throws IOException {
			String message = new String(body, "UTF-8");
			System.out.println(" [1] Received '" + message + "'");

			channel.basicAck(envelope.getDeliveryTag(), false);
		}
	};
	boolean autoAck = false;
	channel.basicConsume(queueName, autoAck, consumer);
}

2.2、消费者2

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private final static String EXCHANGE_NAME = "test_exchange";

public static void main(String[] args) throws Exception {
	ConnectionFactory factory = new ConnectionFactory();
    factory.setHost("192.168.1.7");
    factory.setUsername("root");
    factory.setPassword("123456");
    
	Connection connection = factory.newConnection();
	final Channel channel = connection.createChannel();

	channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
	String queueName = channel.queueDeclare().getQueue();
	// 绑定队列到交换机转发器
	channel.queueBind(queueName, EXCHANGE_NAME, "");
	
	System.out.println(" [2] Waiting for messages. To exit press CTRL+C");
	Consumer consumer = new DefaultConsumer(channel) {
		@Override
		public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties,
				byte[] body) throws IOException {
			String message = new String(body, "UTF-8");
			System.out.println(" [2] Received '" + message + "'");

			channel.basicAck(envelope.getDeliveryTag(), false);
		}
	};
	boolean autoAck = false;
	channel.basicConsume(queueName, autoAck, consumer);
}
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