07. RabbitMQ message success confirmation mechanism

07. RabbitMQ message success confirmation mechanism

• In actual scenarios, the messages sent by some producers must be guaranteed to be successfully sent to the message queue, so how to ensure successful delivery?

• • transaction mechanism
  • Release confirmation mechanism

1. Transaction mechanism

• A way to ensure the successful delivery of messages provided by the AMQP protocol, enabling transactional mode through the channel

• And use the three methods of the channel to send messages in a transactional manner. If the sending fails, the transaction is rolled back through exception handling to ensure the successful delivery of the message.

• • channel.txSelect(): open transaction
  • channel.txCommit() : Commit the transaction
• • channel.txRollback() : rollback the transaction

• Spring has encapsulated the above three methods, so we can only use the original code demonstration

2. Producer code

package trascation;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import util.ConnectionUtil;

/**
 * @author WeiHong
 * @date 2021 -  09 - 15 19:59
 */
public class Sender {
    
    
    public static void main(String[] args) throws Exception {
    
    
        //1.获取连接
        Connection connection = ConnectionUtil.getConnection();
        //2.在连接中创建信道
        Channel channel = connection.createChannel();
        //3.声明路由
        channel.exchangeDeclare("trascation_exchange_topic","topic");
        //4.发送消息
        channel.txSelect();  //开启事务
        try {
    
    
            channel.basicPublish("trascation_exchange_topic","user.weihong",null,"商品1-降价".getBytes());
            System.out.println(3/0);//模拟异常
            channel.basicPublish("trascation_exchange_topic","user.libai",null,"商品2-降价".getBytes());
            channel.basicPublish("trascation_exchange_topic","users123.wangwu",null,"商品3-降价".getBytes());
            System.out.println("生产者已发送！");
            channel.txCommit();//事务提交
        }catch(Exception e){
    
    
            System.out.println("由于系统异常，消息全部撤回！");
            channel.txRollback();//事务回滚
            e.printStackTrace();
        }finally {
    
    
            channel.close();
            connection.close();
        }

    }
}

3. Consumer Code

package trascation;

import com.rabbitmq.client.*;
import util.ConnectionUtil;

import java.io.IOException;

/**
 * @author WeiHong
 * @date 2021 -  09 - 15 20:10
 */
public class Recer1 {
    
    
    public static void main(String[] args) throws Exception {
    
    
        //1.创建连接
        Connection connection = ConnectionUtil.getConnection();
        //2.在连接中创建信道
        Channel channel = connection.createChannel();
        //3.声明队列
        channel.queueDeclare("trscation_queue_topic1",false,false,false,null);
        //4.绑定路由
        channel.queueBind("trscation_queue_topic1","trascation_exchange_topic","user.#");
        //5.定义内部类接收消息
        DefaultConsumer consumer = new DefaultConsumer(channel){
    
    
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
    
    
                String msg = new String(body);
                System.out.println("消费者1="+msg);
            }
        };
        channel.basicConsume("trscation_queue_topic1",true,consumer);


    }
}

4. Experimental results