Rabbitmq的优先级队列

Question

Rabbitmq的优先级队列机制已经过测试，只有在生产者开始在消费者使用之前开始生产者发布消息之前，它才会生效。如何解决这个问题？

**Code snippet**

消费者：

 Map<String,Object> args = new HashMap<String,Object>();
                    args.put("x-max-priority", 10);
 channel.queueDeclare(TEST_PRIORITY_QUEUE, true, false, false,args);
 //omit... ...
 DeliverCallback deliverCallback= (consumerTag, delivery) -> {
            try {
                String message = new String(delivery.getBody(), "UTF-8");
                System.out.println("message="+message);
                Thread.sleep(20*1000);
            }catch (Exception e) {
                e.printStackTrace();
            }finally {
                channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);
            }
 };
//... ...

制作人：

 for (int i = 0; i <20; i++) {
         String messagelow = "lowLevelMsg";
         channel.basicPublish(TEST_EXCHANGE_direct,
                              "prikey", 
                              new BasicProperties.Builder().priority(1).build(), 
                              messagelow.getBytes());
}
           String messagehigh = "HigherLevelMsg";
           channel.basicPublish(TEST_EXCHANGE_direct,
                                "prikey", 
                                new BasicProperties.Builder().priority(9).build(), 
                                messagehigh.getBytes());