RabbitMQ（三）发布确认 Publisher Confirms_could not configure the channel to receive publish

代码仓库：github:https://github.com/stopping5/RabbitMq-Operation-Record.git

本代码示例需要引入rabbitmq依赖

      <!-- rabbitmq依赖客户端-->
       <dependency>
           <groupId>com.rabbitmq</groupId>
           <artifactId>amqp-client</artifactId>
           <version>5.8.0</version>
       </dependency>
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一、什么是发布确认

Publisher confirms are a RabbitMQ extension to implement reliable publishing. When publisher confirms are enabled on a channel, messages the client publishes are confirmed asynchronously by the broker, meaning they have been taken care of on the server side.
发布订阅即使生产者发送消息到broker时，broker可以通过同步或者异步的方式通知消息生产者是否成功。

二、Channel启动消息确认

Channel channel = connection.createChannel();
channel.confirmSelect();
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三、消息发布确认

1. 单条同步确认[耗性能不推荐]

/**
 * 单独确认
 * 消息发送耗时：14492ms
 * */
public static void simpleConfirmMessage() throws IOException, InterruptedException {
    Connection connection = RabbitMqUtil.getConnection();
    Channel channel = connection.createChannel();
    channel.exchangeDeclare(RabbitMQConfig.ACK_EXCHANGE, BuiltinExchangeType.DIRECT);
    //声明队列关闭了自动确认
    channel.queueDeclare(RabbitMQConfig.ACK_QUEUE,false,false,false,null);
    channel.queueBind(RabbitMQConfig.ACK_QUEUE,RabbitMQConfig.ACK_EXCHANGE,"ACK");
    //开启消息确认
    channel.confirmSelect();
    long begin = System.currentTimeMillis();
    for (int i = 0; i < PUBLISH_COUNT; i++) {
        String message = i + "";
        channel.basicPublish(RabbitMQConfig.ACK_EXCHANGE,"ACK",null,message.getBytes(StandardCharsets.UTF_8));
        boolean flag = channel.waitForConfirms();
        if (!flag){
            System.out.println("消息发送失败");
        }
    }
    long end = System.currentTimeMillis();
    System.out.println("消息发送耗时："+(end-begin)+"ms");
}

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或者可以使用Channel#waitForConfirmsOrDie(long)消息如果在限定时间内没有答复则抛出异常

Channel#waitForConfirmsOrDie(long) method. The method returns as soon as the message has been confirmed. If the message is not confirmed within the timeout or if it is nack-ed (meaning the broker could not take care of it for some reason), the method will throw an exception.

2. 批量确认同步确认

使用方式和单条发布确认一样，只不是对消息发布确认频率修改成批量确认模式，若确认失败只能知道一批消息有消息发送失败，无法精确到某一条。

/**
 * 批量发布确认
 * 批量确认消息发送耗时：268ms
 * */
public static void batchConfirmMessage() throws IOException, InterruptedException {
    Connection connection = RabbitMqUtil.getConnection();
    Channel channel = connection.createChannel();
    channel.exchangeDeclare(RabbitMQConfig.ACK_EXCHANGE, BuiltinExchangeType.DIRECT);
    //声明队列关闭了自动确认
    channel.queueDeclare(RabbitMQConfig.ACK_QUEUE,false,false,false,null);
    channel.queueBind(RabbitMQConfig.ACK_QUEUE,RabbitMQConfig.ACK_EXCHANGE,"ACK");
    //开启消息确认
    channel.confirmSelect();
    long begin = System.currentTimeMillis();
    int batchSize = 100;
    for (int i = 0; i < PUBLISH_COUNT; i++) {
        String message = i + "";
        channel.basicPublish(RabbitMQConfig.ACK_EXCHANGE,"ACK",null,message.getBytes(StandardCharsets.UTF_8));
        if (i%batchSize == 0){
            boolean flag = channel.waitForConfirms();
            if (flag){
                System.out.println("消息发送成功");
            }
        }
    }
    long end = System.currentTimeMillis();
    System.out.println("批量确认消息发送耗时："+(end-begin)+"ms");
}
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3. 异步发布确认[推荐]

相对于同步确认而言，异步确认机制新增监听器体提供确认成功和确认失败的方法，复用方法即可异步的获取到消息发送到broker的结果。

/**
 * 批量发布确认
 * 异步确认消息发送耗时：36ms
 * */
public static void asynConfirmMessage() throws IOException, InterruptedException {
    Connection connection = RabbitMqUtil.getConnection();
    Channel channel = connection.createChannel();
    channel.exchangeDeclare(RabbitMQConfig.ACK_EXCHANGE, BuiltinExchangeType.DIRECT);
    //声明队列关闭了自动确认
    channel.queueDeclare(RabbitMQConfig.ACK_QUEUE,false,false,false,null);
    channel.queueBind(RabbitMQConfig.ACK_QUEUE,RabbitMQConfig.ACK_EXCHANGE,"ACK");
    //开启消息确认
    channel.confirmSelect();
    //设置异步监听回调方法
    ConfirmCallback ackCallback = (deliveryTag,multipl)->{
        System.out.println("消息发布确认成功:"+deliveryTag);
    };
    ConfirmCallback unAckCallback = (deliveryTag,multipl)->{
        System.out.println("消息发布失败:"+deliveryTag);
    };
    channel.addConfirmListener(ackCallback,unAckCallback);
    long begin = System.currentTimeMillis();
    for (int i = 0; i < PUBLISH_COUNT; i++) {
        String message = i + "";
        channel.basicPublish(RabbitMQConfig.ACK_EXCHANGE,"ACK",null,message.getBytes(StandardCharsets.UTF_8));
    }
    long end = System.currentTimeMillis();
    System.out.println("异步确认消息发送耗时："+(end-begin)+"ms");
}

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四、总结

1. 优缺点

• 单条同步发布确认：publishing messages individually, waiting for the confirmation synchronously: simple, but very limited throughput.
• 批量同步发布确认：publishing messages in batch, waiting for the confirmation synchronously for a batch: simple, reasonable throughput, but hard to reason about when something goes wrong.
• 异步发布确认：asynchronous handling: best performance and use of resources, good control in case of error, but can be involved to implement correctly.

2. 效率

测试结果可以看出异步确认效率是最高的，其次是批量确认，最后当然是一条一条的单条确认。

public static void main(String[] args) throws IOException, InterruptedException {
    //simpleConfirmMessage();//消息发送耗时：14492ms
    //batchConfirmMessage();//批量确认消息发送耗时：268ms
    //asynConfirmMessage();//异步确认消息发送耗时：36ms
}
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