07. RabbitMQ消息成功确认机制

在实际场景下，有的生产者发送的消息是必须保证成功发送到消息队列中，那么如何保证成功投递呢？

事务机制发布确认机制 1.事务机制

AMQP协议提供的一种保证消息成功投递的方式，通过信道开启 transactional 模式

并利用信道 的三个方法来实现以事务方式 发送消息，若发送失败，通过异常处理回滚事务，确保消息成功投递

channel.txSelect()： 开启事务channel.txCommit() ：提交事务

channel.txRollback() ：回滚事务

Spring已经对上面三个方法进行了封装，所以我们只能使用原始的代码演示

package trascation;

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


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();
        }

    }
}

package trascation;

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

import java.io.IOException;


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);


    }
}