操作014：惰性队列

一、创建惰性队列

1、官网说明

队列可以创建为默认或惰性模式，模式指定方式是：

使用队列策略（建议）
设置queue.declare参数

如果策略和队列参数同时指定，那么队列参数有更高优先级。如果队列模式是在声明时通过可选参数指定的，那么只能通过删除队列再重新创建来修改。

2、基于策略方式设定

# 登录Docker容器
docker exec -it rabbitmq /bin/bash

# 运行rabbitmqctl命令
rabbitmqctl set_policy Lazy "^lazy-queue$" '{"queue-mode":"lazy"}' --apply-to queues

命令解读：

rabbitmqctl命令所在目录是：/opt/rabbitmq/sbin，该目录已配置到Path环境变量
set_policy是子命令，表示设置策略
Lazy是当前要设置的策略名称，是我们自己自定义的，不是系统定义的
"^lazy-queue$"是用正则表达式限定的队列名称，凡是名称符合这个正则表达式的队列都会应用这里的设置
'{"queue-mode":"lazy"}'是一个JSON格式的参数设置指定了队列的模式为"lazy"
–-apply-to参数指定该策略将应用于队列（queues）级别
命令执行后，所有名称符合正则表达式的队列都会应用指定策略，包括未来新创建的队列

如果需要修改队列模式可以执行如下命令（不必删除队列再重建）：

rabbitmqctl set_policy Lazy "^lazy-queue$" '{"queue-mode":"default"}' --apply-to queues

3、在声明队列时使用参数设定

参数名称：x-queue-mode
可用参数值：
- default
- lazy
不设置就是取值为default

Java代码原生API设置方式：

Map<String, Object> args = new HashMap<String, Object>();
args.put("x-queue-mode", "lazy");
channel.queueDeclare("myqueue", false, false, false, args);

Java代码注解设置方式：

@Queue(value = QUEUE_NAME, durable = "true", autoDelete = "false", arguments = {
    @Argument(name = "x-queue-mode", value = "lazy")
})

二、实操演练

1、生产者端代码

①配置POM

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.1.5</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-amqp</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>

②配置YAML

spring:
  rabbitmq:
    host: 192.168.200.100
    port: 5672
    username: guest
    password: 123456
    virtual-host: /

③主启动类

package com.atguigu.mq;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class RabbitMQLazyProducer {

    public static void main(String[] args) {
        SpringApplication.run(RabbitMQLazyProducer.class, args);
    }

}

④发送消息

package com.atguigu.mq.test;

import jakarta.annotation.Resource;
import org.junit.jupiter.api.Test;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
public class RabbitMQTest {

    public static final String EXCHANGE_LAZY_NAME = "exchange.atguigu.lazy";
    public static final String ROUTING_LAZY_KEY = "routing.key.atguigu.lazy";

    @Resource
    private RabbitTemplate rabbitTemplate;

    @Test
    public void testSendMessage() {
        rabbitTemplate.convertAndSend(EXCHANGE_LAZY_NAME, ROUTING_LAZY_KEY, "I am a message for test lazy queue.");
    }

}

2、消费者端代码

①配置POM

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.1.5</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-amqp</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>

②配置YAML

spring:
  rabbitmq:
    host: 192.168.200.100
    port: 5672
    username: guest
    password: 123456
    virtual-host: /

③主启动类

package com.atguigu.mq;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class RabbitMQLazyConsumerMainType {

    public static void main(String[] args) {
        SpringApplication.run(RabbitMQLazyConsumerMainType.class, args);
    }

}

④监听器

package com.atguigu.mq.listener;

import com.rabbitmq.client.Channel;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.annotation.*;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class MyLazyMessageProcessor {

    public static final String EXCHANGE_LAZY_NAME = "exchange.atguigu.lazy";
    public static final String ROUTING_LAZY_KEY = "routing.key.atguigu.lazy";
    public static final String QUEUE_LAZY_NAME = "queue.atguigu.lazy";

    @RabbitListener(bindings = @QueueBinding(
        value = @Queue(value = QUEUE_LAZY_NAME, durable = "true", autoDelete = "false", arguments = {
            @Argument(name = "x-queue-mode", value = "lazy")
        }),
        exchange = @Exchange(value = EXCHANGE_LAZY_NAME, durable = "true", autoDelete = "false"),
        key = {ROUTING_LAZY_KEY}
    ))
    public void processMessageLazy(String data, Message message, Channel channel) {
        log.info("消费端接收到消息：" + data);
    }

}