Code practice when the queue reaches the maximum length

producer 001

/**
 *  When the queue reaches the maximum length 
 */
public class Producer001 {
    private  static  final  String NORMAL_EXCHANGE="normal_exchange";

    public static void main(String[] args) throws  Exception{
        Channel channel = untils.getChannel();
        channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
        // This message is used as the number limit of queues 
        for(int i=0;i<10;i++)
        {
            String message="info"+i;
            channel.basicPublish(NORMAL_EXCHANGE,"zhangsan",null,message.getBytes(StandardCharsets.UTF_8));
            System.out.println(" Producer sends message "+message);
        }
    }
}

consumer 001 

/**
 *  Average consumer with maximum queue length 
 */
public class Consumer001 {

        // General switch 
        private  static  final  String NORMAL_EXCHANGE="normal_exchange";
        // Dead letter switch 
        private  static  final  String DEAD_EXCHANGE="dead_exchange";

        public static void main(String[] args) throws  Exception{
            Channel channel = untils.getChannel();
            // Declare dead letter switch , The type is direct
            channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
            channel.exchangeDeclare(DEAD_EXCHANGE,BuiltinExchangeType.DIRECT);
            // Declare dead letter queue 
            String deadQueue="dead_queue";
            channel.queueDeclare(deadQueue,false,false,false,null);
            // Dead letter queue binding exchange and routingKey value 
            channel.queueBind(deadQueue,DEAD_EXCHANGE,"lisi");
            // The normal queue is bound to the dead letter queue 
            Map<String,Object> params=new HashMap<>();
            // Set the dead letter switch in the normal queue , Parameters key It's a fixed value 
            params.put("x-dead-letter-exchange",DEAD_EXCHANGE);
            // Set dead letter in normal queue routing-key, Parameters key It's a fixed value 
            params.put("x-dead-letter-routing-key", "lisi");
            // Maximum limit length of normal queue settings 
            params.put("x-max-length",6);
            System.out.println(" Waiting to receive message ....");
            String normalQueue="normal_queue";
            channel.queueDeclare(normalQueue,false,false,false,params);
            channel.queueBind(normalQueue,NORMAL_EXCHANGE,"zhangsan");
            DeliverCallback deliverCallback=(consumerTag, message) -> {
                String s = new String(message.getBody(), StandardCharsets.UTF_8);
                System.out.println("01 Message received "+s);
            };
            channel.basicConsume(normalQueue,true,deliverCallback,consumerTag -> {});
        }
}

  result ：