RabbitMQ（高级特性）优先级队列

假设在电商系统中有一个订单催付的场景，即客户在一段时间内未付款会给用户推送一条短信提醒，但是系统中分为大型商家和小型商家。比如像苹果，小米这样大商家一年能给我们创造很大的利润，所以在订单量大时，他们的订单必须得到优先处理，此时就需要为不同的消息设置不同的优先级，此时我们要使用优先级队列。

创建队列和交换机

@Configuration
public class RabbitConfig3 {private final String EXCHANGE_NAME="priority_exchange";private final String QUEUE_NAME="priority_queue";// 1.创建交换机@Bean(EXCHANGE_NAME)public Exchange priorityExchange(){return ExchangeBuilder.topicExchange(EXCHANGE_NAME).durable(true).build();}// 2.创建队列@Bean(QUEUE_NAME)public Queue priorityQueue(){return QueueBuilder.durable(QUEUE_NAME)//设置队列的最大优先级，最大可以设置到255，官网推荐不要超过10，,如果设置太高比较浪费资源.maxPriority(10).build();}// 3.将队列绑定到交换机@Beanpublic Binding bindPriority(@Qualifier(EXCHANGE_NAME) Exchange exchange, @Qualifier(QUEUE_NAME) Queue queue){return BindingBuilder.bind(queue).to(exchange).with("my_routing").noargs();}
}

编写生产者

@Test
public void testPriority() {for (int i = 0; i < 10; i++) {if (i == 5) {// i为5时消息的优先级较高MessageProperties messageProperties = new MessageProperties();messageProperties.setPriority(9);Message message = new Message(("send message..." + i).getBytes(StandardCharsets.UTF_8), messageProperties);rabbitTemplate.convertAndSend("priority_exchange", "my_routing", message);} else {rabbitTemplate.convertAndSend("priority_exchange", "my_routing", "send message..." + i);}}
}

编写消费者

@Component
public class PriorityConsumer {@RabbitListener(queues = "priority_queue")public void listenMessage(Message message, Channel channel) throws Exception {//获取消息System.out.println(new String(message.getBody()));//手动签收channel.basicAck(message.getMessageProperties().getDeliveryTag(),true);}
}

优先级越高，越先被消费