1.SleepUtil线程睡眠工具类

package com.hong.utils;

/**
 * @Description: 线程睡眠工具类
 * @Author: hong
 * @Date: 2023-12-16 23:10
 * @Version: 1.0
 **/
public class SleepUtil {
    public static void sleep(int second) {
        try {
            Thread.sleep(1000*second);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }
}

2.消息生产者

package com.hong.rabbitmq3;

import com.hong.utils.RabbitMQUtil;
import com.rabbitmq.client.Channel;

import java.util.Scanner;

/**
 * @Description: 消息手动应答时不丢失,放回队列重新消费
 * @Author: hong
 * @Date: 2023-12-16 22:33
 * @Version: 1.0
 **/
public class Task3 {

    public static final String TASK_QUEUE_NAME = "ack_queue";

    public static void main(String[] args) throws Exception{
        Channel channel = RabbitMQUtil.getChannel();
        channel.queueDeclare(TASK_QUEUE_NAME,false,false,false,null);
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入:");
        while (scanner.hasNext()){
            String message = scanner.next();
            channel.basicPublish("",TASK_QUEUE_NAME,null,message.getBytes("UTF-8"));
            System.out.println("消息发送完成------" + message);
        }
    }
}

3.两个消费者

模拟一个处理速度快(Worker3),另一个处理速度慢(Worker4)

3.1.处理时间短

package com.hong.rabbitmq3;

import com.hong.utils.RabbitMQUtil;
import com.hong.utils.SleepUtil;
import com.rabbitmq.client.CancelCallback;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;

/**
 * @Description: 消息手动应答时不丢失,放回队列重新消费
 * @Author: hong
 * @Date: 2023-12-16 23:05
 * @Version: 1.0
 **/
public class Worker3 {
    private static final String TASK_QUEUE_NAME = "ack_queue";

    public static void main(String[] args) throws Exception{
        Channel channel = RabbitMQUtil.getChannel();
        System.out.println("worker3等待接收消息,处理速度快");

        DeliverCallback deliverCallback = (comsumerTag, message) -> {
            SleepUtil.sleep(1);
            System.out.println("接收到的消息:"+  new String(message.getBody(),"UTF-8"));
            //手动应答
            /**
             * 第一个参数:消息标识
             * 第二个参数是否批量:true批量
             */
            channel.basicAck(message.getEnvelope().getDeliveryTag(),false);
        };

        CancelCallback cancelCallback = var -> System.out.println(var + "消息消费被中断!");
        //手动应答false
       channel.basicConsume(TASK_QUEUE_NAME,false,deliverCallback,cancelCallback);
    }
}

3.2.处理时间长

package com.hong.rabbitmq3;

import com.hong.utils.RabbitMQUtil;
import com.hong.utils.SleepUtil;
import com.rabbitmq.client.CancelCallback;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;

/**
 * @Description: 消息手动应答时不丢失, 放回队列重新消费
 * @Author: hong
 * @Date: 2023-12-16 23:05
 * @Version: 1.0
 **/
public class Worker4 {
    private static final String TASK_QUEUE_NAME = "ack_queue";

    public static void main(String[] args) throws Exception{
        Channel channel = RabbitMQUtil.getChannel();
        System.out.println("worker4等待接收消息,处理速度慢");

        DeliverCallback deliverCallback = (comsumerTag, message) -> {
            SleepUtil.sleep(20);
            System.out.println("接收到的消息:"+  new String(message.getBody(),"UTF-8"));
            //手动应答
            /**
             * 第一个参数:消息标识
             * 第二个参数是否批量:true批量
             */
            channel.basicAck(message.getEnvelope().getDeliveryTag(),false);
        };

        CancelCallback cancelCallback = var -> System.out.println(var + "消息消费被中断!");
        
        //手动应答false
       channel.basicConsume(TASK_QUEUE_NAME,false,deliverCallback,cancelCallback);
    }
}

4.结果

启动生产者后启动2个消费者，等消息bb接收到后，发送cc和dd


等Worker4接收到消息bb后将其关闭,发现原本该Worker4消费的消息dd并未丢失,重回队列被Worker3消费

5.持久化

5.1.队列持久化

package com.hong.rabbitmq4;

import com.hong.utils.RabbitMQUtil;
import com.rabbitmq.client.Channel;

import java.util.Scanner;

/**
 * @Description: 队列持久化
 * @Author: hong
 * @Date: 2023-12-17 22:52
 * @Version: 1.0
 **/
public class Task4 {
    public static final String TASK_QUEUE_NAME = "persist_queue";

    public static void main(String[] args) throws Exception{
        Channel channel = RabbitMQUtil.getChannel();
        //true持久化
        channel.queueDeclare(TASK_QUEUE_NAME,true,false,false,null);
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入:");
        while (scanner.hasNext()){
            String message = scanner.next();
            channel.basicPublish("",TASK_QUEUE_NAME,null,message.getBytes("UTF-8"));
            System.out.println("消息发送完成------" + message);
        }
    }
}

5.2.消息持久化

package com.hong.rabbitmq4;

import com.hong.utils.RabbitMQUtil;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.MessageProperties;

import java.util.Scanner;

/**
 * @Description: 队列持久化与消息持久化
 * @Author: hong
 * @Date: 2023-12-17 22:52
 * @Version: 1.0
 **/
public class Task4 {
    public static final String TASK_QUEUE_NAME = "persist_queue";

    public static void main(String[] args) throws Exception{
        Channel channel = RabbitMQUtil.getChannel();
        //队列持久化   true持久化
        channel.queueDeclare(TASK_QUEUE_NAME,true,false,false,null);
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入:");
        while (scanner.hasNext()){
            String message = scanner.next();
            //消息持久化  MessageProperties.PERSISTENT_TEXT_PLAIN
            channel.basicPublish("",TASK_QUEUE_NAME, MessageProperties.PERSISTENT_TEXT_PLAIN,message.getBytes("UTF-8"));
            System.out.println("消息发送完成------" + message);
        }
    }
}