rabbitmq(3)消息队列(轮询分发)

拼搏现实的明天。 2022-05-29 14:06 186阅读 0赞

### 1、模型 ###

一个生产者绑定一个队列，对应多个消费者：  
![这里写图片描述][20180325160323120]

### 2、代码 ###

#### 2.1、生产者 ####

#### 2.2、消费者1 ####

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();
        Channel channel = connection.createChannel();
    
        channel.queueDeclare(QUEUE_NAME, true, false, false, null);
        System.out.println(" [1] Waiting for messages.");
        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 + "'");
            }
        };
        /* * 自动确认,一旦rabbitmq将消息发送到消费者,则rabbitmq将删除该消息 * 若消费者未处理完消息前中断,会导致消息丢失的问题 */
        boolean autoAck = true;
        channel.basicConsume(QUEUE_NAME, autoAck, consumer);
    }

#### 2.3、消费者2 ####

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();
        Channel channel = connection.createChannel();
    
        channel.queueDeclare(QUEUE_NAME, true, false, false, null);
        System.out.println(" [2] Waiting for messages.");
        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 + "'");
                // 让消费者2处理速度远低于消费者1
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        };
        boolean autoAck = true;
        channel.basicConsume(QUEUE_NAME, autoAck, consumer);
    }

### 3、效果 ###

即使消费者2的处理速度远低于消费者1，两者接收到的任务数量几乎相同，即rabbitmq将消息均匀分发给所有消费者，即使其中有的消费者闲置有的消费者高负荷。

[20180325160323120]: /images/20220529/7f080d7594d34ba9ad9e2d54a67730d5.png