RabbitMQ消息模式

1、消息如何保证100%的投递？

2、幂等性概念

3、Confirm确认消息

4、Return返回消息

5、自定义消费者

消息100%的投递

消息如何保障100%的投递成功？

什么是生产端的可靠性投递？

u 保障消息的成功发出

u 保障MQ节点的成功接收

u 发送端收到MQ节点（Broker）确认应答

u 完善的消息进行补偿机制

 

BAT/TMD互联网大厂的解决方案：

u 消息落库，对消息状态进行打标

u 消息的延迟投递，做二次确认，回调检查

 

幂等性概念

幂等性是什么？

u 我们可以借鉴数据库的乐观锁机制

u 比如我们执行一条更新库存的SQL语句

u Update t_repository set count = count -1,version = version + 1 where version = 1

u Elasticsearch也是严格遵循幂等性概念，每次数据更新，version+1（博主博客前面有提到）

 

消费端-幂等性保障

在海量订单产生的业务高峰期，如何避免消息的重复消费问题？

消费实现幂等性，就意味着，我们的消息永远不会消费多次，即使我们收到了多条一样的消息

 

业界主流的幂等性操作

唯一ID+指纹码机制，利用数据库主键去重

利用Redis的原子性去实现

 

唯一ID+指纹码 机制

唯一ID+指纹码机制，利用数据库主键去重

Select count(1) from T_order where ID=唯一ID+指纹码

好处：实现简单

坏处：高并发下有数据库写入的性能瓶颈

解决方案：根据ID进行分库分表进行算法路由

 

利用Redis的原子性去实现

使用Redis进行幂等，需要考虑的问题

第一：我们是否要进行数据落库，如果落库的话，关键解决的问题是数据库和缓存如何做到原子性？

第二：如果不进行落库，那么都存储到缓存中，如何设置定时同步策略？

Confirm确认消息

理解Confirm消息确认机制

消息的确认，是指生产者投递消息后，如果Broker收到消息，则会给我们生产者 一个应答。

生产者进行接收应答，用来确定这条消息是否正常的发送到Broker，这种方式也是消息的可靠性投递的核心保障

如何实现Confirm确认消息？

第一步：在Channel上开启确认模式：channel.confirmSelect()

第二步：在channel上添加监听：addConfirmListener，监听成功和失败的返回结果，根据具体的结果对消息进行重新发送、或记录日志等后续处理！

消费端代码：

package com.psy.rabbitmqapi.confirm;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.QueueingConsumer;


public class Consumer {
    public static void main(String[] args) throws Exception {
        //1 创建ConnectionFactory
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.254.128");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        //2 获取C    onnection
        Connection connection = connectionFactory.newConnection();

        //3 通过Connection创建一个新的Channel
        Channel channel = connection.createChannel();

        String exchangeName = "test_confirm_exchange";
        String routingKey = "confirm.#";
        String queueName = "test_confirm_queue";

        //4 声明交换机和队列 然后进行绑定设置, 最后制定路由Key
        channel.exchangeDeclare(exchangeName, "topic", true);
        channel.queueDeclare(queueName, true, false, false, null);
        channel.queueBind(queueName, exchangeName, routingKey);

        //5 创建消费者
        QueueingConsumer queueingConsumer = new QueueingConsumer(channel);
        channel.basicConsume(queueName, true, queueingConsumer);

        while(true){
            QueueingConsumer.Delivery delivery = queueingConsumer.nextDelivery();
            String msg = new String(delivery.getBody());

            System.err.println("消费端: " + msg);
        }


    }
}

服务提供方代码：

package com.psy.rabbitmqapi.confirm;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.ConfirmListener;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

import java.io.IOException;


public class Producer {
    public static void main(String[] args) throws Exception {
        //1 创建ConnectionFactory
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.254.128");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        //2 获取C    onnection
        Connection connection = connectionFactory.newConnection();

        //3 通过Connection创建一个新的Channel
        Channel channel = connection.createChannel();


        //4 指定我们的消息投递模式: 消息的确认模式
        channel.confirmSelect();

        String exchangeName = "test_confirm_exchange";
        String routingKey = "confirm.save";

        //5 发送一条消息
        String msg = "Hello RabbitMQ Send confirm message!";
        channel.basicPublish(exchangeName, routingKey, null, msg.getBytes());

        //6 添加一个确认监听
        channel.addConfirmListener(new ConfirmListener() {
            @Override
            public void handleNack(long deliveryTag, boolean multiple) throws IOException {
                System.err.println("-------no ack!-----------");
            }

            @Override
            public void handleAck(long deliveryTag, boolean multiple) throws IOException {
                System.err.println("-------ack!-----------");
            }
        });
    }
}

Return返回消息

Return Listener用于处理一些不可路由的消息！

正常情况：我们的消息生产者，通过指定一个Exchange和RoutingKey，把消息送达到某一个队列中去，然后我们的消费者监听队列，进行消费处理操作！

异常情况：在某些情况下，如果我们在发送消息的时候，当前的Exchange不存在或者指定的路由key路由不到，这个时候如果我们需要监听这种不可达的消息，就需要使用Return Listener！

 

在基础API中有一个关键的配置项

Mandatory：如果为true，则监听器会接收到路由不可达的消息，然后进行后续处理，如果为false，那么Broker端自动删除该消息！

 

  　　

消费端代码：

package com.psy.rabbitmqapi.returnlistener;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.QueueingConsumer;


public class Consumer {
    public static void main(String[] args) throws Exception {
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.254.128");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();

        String exchangeName = "test_return_exchange";
        String routingKey = "return.#";
        String queueName = "test_return_queue";

        channel.exchangeDeclare(exchangeName, "topic", true, false, null);
        channel.queueDeclare(queueName, true, false, false, null);
        channel.queueBind(queueName, exchangeName, routingKey);

        QueueingConsumer queueingConsumer = new QueueingConsumer(channel);

        channel.basicConsume(queueName, true, queueingConsumer);

        while(true){
            QueueingConsumer.Delivery delivery = queueingConsumer.nextDelivery();
            String msg = new String(delivery.getBody());
            System.err.println("消费者: " + msg);
        }

    }
}

生产端代码：

package com.psy.rabbitmqapi.returnlistener;

import com.rabbitmq.client.*;

import java.io.IOException;


public class Producer {
    public static void main(String[] args) throws Exception {
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.254.128");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();

        String exchange = "test_return_exchange";
        String routingKey = "return.save";
        String routingKeyError = "abc.save";

        String msg = "Hello RabbitMQ Return Message";


        channel.addReturnListener(new ReturnListener() {
            @Override
            public void handleReturn(int replyCode, String replyText, String exchange,
                                     String routingKey, AMQP.BasicProperties properties, byte[] body) throws IOException {

                System.err.println("---------handle  return----------");
                System.err.println("replyCode: " + replyCode);
                System.err.println("replyText: " + replyText);
                System.err.println("exchange: " + exchange);
                System.err.println("routingKey: " + routingKey);
                System.err.println("properties: " + properties);
                System.err.println("body: " + new String(body));
            }
        });

        //消息投递成功，会被消费者所消费
//        channel.basicPublish(exchange, routingKey, true, null, msg.getBytes());
        //消息不可达，将触发ReturnListener
         channel.basicPublish(exchange, routingKeyError, true, null, msg.getBytes());
    }
}

自定义消费者

我们一般就是在代码中编写while循环，进行consumer.nextDelivery方法进行获取下一条消息，然后进行消费处理！

但是我们使用自定义的Consumer更加的方便，解耦性更加的强，也是实际工作中最常用的使用方式！

 

自定义消费端代码

package com.psy.rabbitmqapi.consumer;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;

import java.io.IOException;


public class MyConsumer extends DefaultConsumer {


    public MyConsumer(Channel channel) {
        super(channel);
    }

    @Override
    public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
        System.err.println("-----------consume message----------");
        System.err.println("consumerTag: " + consumerTag);
        System.err.println("envelope: " + envelope);
        System.err.println("properties: " + properties);
        System.err.println("body: " + new String(body));
    }
}

消费端调用：

package com.psy.rabbitmqapi.consumer;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;


public class Consumer {
    public static void main(String[] args) throws Exception {
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.254.128");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();


        String exchangeName = "test_consumer_exchange";
        String routingKey = "consumer.#";
        String queueName = "test_consumer_queue";

        channel.exchangeDeclare(exchangeName, "topic", true, false, null);
        channel.queueDeclare(queueName, true, false, false, null);
        channel.queueBind(queueName, exchangeName, routingKey);

        channel.basicConsume(queueName, true, new MyConsumer(channel));


    }
}

生产端调用：

package com.psy.rabbitmqapi.consumer;

import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;


public class Producer {
    public static void main(String[] args) throws Exception {
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("192.168.254.128");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();

        String exchange = "test_consumer_exchange";
        String routingKey = "consumer.save";

        String msg = "Hello RabbitMQ Consumer Message";

        for(int i =0; i<5; i ++){
            channel.basicPublish(exchange, routingKey, true, null, msg.getBytes());
        }

    }
}