rabbitmq(4)消息队列(公平分发)

rabbitmq

1、目标

实现rabbitmq将消息优先发给闲置的消费者。

2、代码

2.1、生产者

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private final static String QUEUE_NAME = "hello";

@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();
	
	channel.queueDeclare(QUEUE_NAME, true, false, false, null);
	for(int i=0;i<20;i++) {
		String message = "Hello "+i;
		channel.basicPublish("", QUEUE_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 QUEUE_NAME = "hello";

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();

	// 消费者最多接受1条消息,直到应答后接受新消息。保证rabbitmq每次将消息发送给闲置的消费者
	int prefetchCount = 1;
	channel.basicQos(prefetchCount);

	channel.queueDeclare(QUEUE_NAME, true, false, false, null);
	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 + "'");
			try {
				Thread.sleep(200);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}

			// 手动应答
			channel.basicAck(envelope.getDeliveryTag(), false);
		}
	};
	/*
	 *  使用公平分发,必须关闭自动应答,使用手动应答
	 *  当消费者应答rabbitmq后,rabbitmq将删除该消息
	 *  保证即时消费者接受消息后(未应答)中断,rabbitmq也会将该消息发送给其他消费者而不会出现消息丢失的问题
	 */
	boolean autoAck = false;
	channel.basicConsume(QUEUE_NAME, autoAck, consumer);
}

2.2、消费者2

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private final static String QUEUE_NAME = "hello";

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();

	int prefetchCount = 1;
	channel.basicQos(prefetchCount);

	channel.queueDeclare(QUEUE_NAME, true, false, false, null);
	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 + "'");
			try {
				Thread.sleep(500);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			channel.basicAck(envelope.getDeliveryTag(), false);
		}
	};
	boolean autoAck = false;
	channel.basicConsume(QUEUE_NAME, autoAck, consumer);
}
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