rabbitmq(4)消息队列(公平分发)

心已赠人 2022-05-29 14:07 216阅读 0赞

### 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 ####

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 ####

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 ####

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);
    }