关于rabbitmq消息延迟队列简单实现

简单来说就是消息先发送至一般队列中，不监听一般队列中的消息。等待设置的延迟时间过后，消息由一般队列发送至死信队列，监听死信队列接收消息，完成消息延迟。

1.声明绑定一般队列和交换机，死信队列和交换机（配置文件中做rabbit配置）

@Configuration
public class MqConfig {
    @Bean
    public Queue ttlQueue() {
        Map<String,Object> map = new HashMap<>(1);
        //延迟时间
        map.put("x-message-ttl", 1000*10);
        // 设置消息成为死信后，传发到的路由器
        map.put("x-dead-letter-exchange","dead.direct.exchange");
        map.put("x-dead-letter-routing-key", "dead");
        return new Queue("ttl.queue", true, false, false, map);
    }

    @Bean
    public DirectExchange ttlDirectExchange() {
        return new DirectExchange("ttl.direct.exchange", true, false);
    }

    @Bean
    public Binding ttlDirectBinding() {
        return BindingBuilder
                .bind(ttlQueue())
                .to(ttlDirectExchange())
                .with("ttl");
    }

// =======================以下为死信队列相关配置=========================

    @Bean
    public Queue deadQueue() {
        return new Queue("dead.queue", true);
    }

    @Bean
    public DirectExchange deadDirectExchange() {
        return new DirectExchange("dead.direct.exchange", true, false);
    }

    @Bean
    public Binding deadDirectBinding() {
        return BindingBuilder
                .bind(deadQueue())
                .to(deadDirectExchange())
                .with("dead");
    }
}

2.消息生产者发送消息

rabbitTemplate.convertAndSend("ttl.direct.exchange","ttl",order.getId());

3.消息消费者监听消息

@RabbitListener(queues = "dead.queue")
public void deadQueue(Long orderId) {
//以下为业务内容
    Order order = orderService.getById(orderId);
    if (order.getStatus() == 1) {
        log.info("超时未支付，取消订单");
        LambdaQueryWrapper<OrderDetail> qw = new LambdaQueryWrapper<>();
        qw.eq(OrderDetail::getOrderId, orderId);
        OrderDetail detail = orderDetailMapper.selectOne(qw);
        Integer num = detail.getNum();//商品购买数量
        order.setStatus(5);
        orderService.updateById(order);//修改订单状态
        itemClient.updateStock(orderId, num, false);//恢复商品库存
    }
}