详解RabbitMQ高级特性之事务

事务

RabbitMQ是基于AMQP协议实现的, 该协议实现了事务机制, 因此RabbitMQ也⽀持事务机制. Spring AMQP也提供了对事务相关的操作. RabbitMQ事务允许开发者确保消息的发送和接收是原⼦性的, 要么全部成功, 要么全部失败.

添加配置

spring:
  application:
    name: rabbit-extensions-demo
  rabbitmq:
    addresses: amqp://study:study@47.98.109.138:5672/extension

常量类

public class Constants {
    //事务
    public static final String TRANS_QUEUE = "trans.queue";
}

声明队列

import org.springframework.amqp.core.*;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import rabbitextensionsdemo.constant.Constants;
@Configuration
public class RabbitMQConfig {
    @Bean("transQueue")
    public Queue transQueue(){
        return QueueBuilder.durable(Constants.TRANS_QUEUE).build();
    }
}

设置RabbitTemplate

import org.springframework.amqp.core.ReturnedMessage;
import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.connection.CorrelationData;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class RabbitTemplateConfig {
    @Bean("transRabbitTemplate")
    public RabbitTemplate transRabbitTemplate(ConnectionFactory connectionFactory){
        RabbitTemplate rabbitTemplate = new RabbitTemplate(connectionFactory);
        rabbitTemplate.setChannelTransacted(true);  //开启事务
        return rabbitTemplate;
    }
}

编写生产消息代码1

    @Transactional
    @RequestMapping("/trans")
    public String trans(){
        transRabbitTemplate.convertAndSend("",Constants.TRANS_QUEUE, "trans test 1...");
        transRabbitTemplate.convertAndSend("",Constants.TRANS_QUEUE, "trans test 2...");
        return "消息发送成功";
    }

观察效果

此时我们可以看到，两条消息都进入了队列。

编写生产消息代码2

    @Transactional
    @RequestMapping("/trans")
    public String trans(){
        transRabbitTemplate.convertAndSend("",Constants.TRANS_QUEUE, "trans test 1...");
        int num = 5/0;
        transRabbitTemplate.convertAndSend("",Constants.TRANS_QUEUE, "trans test 2...");
        return "消息发送成功";
    }

观察效果

此时我们发现，抛异常了，但是队列中居然有1条消息，怎么回事？我们不是开启事务了吗？

原因是因为我们没有配置事务管理器

配置事务管理器

import org.springframework.amqp.core.ReturnedMessage;
import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.connection.CorrelationData;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.amqp.rabbit.transaction.RabbitTransactionManager;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class RabbitTemplateConfig {
    @Bean("transRabbitTemplate")
    public RabbitTemplate transRabbitTemplate(ConnectionFactory connectionFactory){
        RabbitTemplate rabbitTemplate = new RabbitTemplate(connectionFactory);
        rabbitTemplate.setChannelTransacted(true);  //开启事务
        return rabbitTemplate;
    }
    @Bean
    public RabbitTransactionManager rabbitTransactionManager(ConnectionFactory connectionFactory){
        return new RabbitTransactionManager(connectionFactory);
    }
}

观察效果

此时我们可以看到，生产消息时抛异常了，因为开启了事务，所以生产的消息没有入队列，且结果符合预期。