第三章 （5）确认消息

理解消息的确认机制

• 消息的确认，值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
• 生产者接收应答，用来确定这条消息是否正常发送到Broker，这种方式也是消息可靠性投递的核心保障

确认机制流程图

Confirm 确认消息实现

• 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，根据具体的消息进行重新发送、或记录日志等后续处理！

代码编写

生产端代码

package club.yunqiang.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;
import java.util.concurrent.TimeoutException;

/**
 * @author zyq
 * @date 2019/12/7
 */
public class Producer {

    public static void main(String[] args) throws IOException, TimeoutException {
        // 1、创建ConnectionFactory
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("localhost");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

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

        // 3、通过 Connection 获取 Channel
        Channel channel = connection.createChannel();

        // 4、指定消息的确认模式
        channel.confirmSelect();

        // 5、投递消息
        String exchangeName = "test_confirm_exchange";
        String routingKey = "confirm.save";
        String msg = "Hello RabbitMQ send confirm message!";
        channel.basicPublish(exchangeName, routingKey, null, msg.getBytes());

        // 6、添加确认监听
        channel.addConfirmListener(new ConfirmListener() {
            @Override
            public void handleAck(long deliveryTag, boolean multiple) throws IOException {
                System.out.println("----- ack! -----");
            }

            @Override
            public void handleNack(long deliveryTag, boolean multiple) throws IOException {
                System.out.println("----- no ack! -----");
            }
        });
    }

}

消费端代码

package club.yunqiang.rabbitmqapi.confirm;

import com.rabbitmq.client.*;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.concurrent.TimeoutException;

/**
 * @author zyq
 * @date 2019/12/7
 */
public class Consumer {

    public static void main(String[] args) throws IOException, TimeoutException {
        // 1、创建ConnectionFactory
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost("localhost");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");

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

        // 3、通过 Connection 获取 Channel
        Channel channel = connection.createChannel();


        // 4、声明 exchange
        String exchangeName = "test_confirm_exchange";
        String routingKey = "confirm.#";
        channel.exchangeDeclare(exchangeName, "topic", true);

        // 5、声明 queue
        String queueName = "test_confirm_queue";
        channel.queueDeclare(queueName, true, false, false, null);

        // 6、绑定 exchange 和 queue
        channel.queueBind(queueName, exchangeName, routingKey);

        // 7、创建消费者
        DefaultConsumer defaultConsumer = new DefaultConsumer(channel){
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                String msg = new String(body, StandardCharsets.UTF_8);
                System.out.println(String.format("消费端%s", msg));
            }
        };

        channel.basicConsume(queueName, true, defaultConsumer);
    }

}

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