RabbitMQ高级特性-消费端ACK与重回队列

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消费端ACK与重回队列

消费端ACK

• 消费端的手工ACK和NACK, ACK是确认成功消费, NACK表示消息处理失败, 会重发消息
• 消费端进行消费的时候, 如果由于业务异常我们可以进行日志的记录, 然后进行补偿
• 如果由于服务器宕机等严重问题, 就需要手工进行ACK保障消费端消费成功

重回队列

• 消费端重回队列是为了对没有处理成功的消息, 把消息重新回递给Broker
• 一般在实际应用中, 都会关闭重回队列, 也就是设置为False

代码演示

自定义消费者

package com.qiyexue.api.ack;

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

import java.io.IOException;
import java.util.concurrent.TimeUnit;

/**
 * 自定义消费者
 * 设置手动ack和重回队列
 * @author 七夜雪
 * @date 2018-12-16 8:20
 */
public class MyConsumer extends DefaultConsumer {
    private Channel channel;

    public MyConsumer(Channel channel) {
        super(channel);
        this.channel = channel;
    }

    @Override
    public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
        System.out.println("-------------自定义消费者------------");
        System.out.println("consumerTag : " + consumerTag);
        System.out.println("envelope : " + envelope);
        System.out.println("properties : " + properties);
        System.out.println("body : " + new String(body));
        try {
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        if ((Integer)properties.getHeaders().get("num") == 0) {
            // 三个参数 : DeliveryTag, 是否批量拒绝, 是否可以重回队列
            channel.basicNack(envelope.getDeliveryTag(), false, true);
        } else {
            channel.basicAck(envelope.getDeliveryTag(), false);
        }

    }
}

Producer

package com.qiyexue.api.ack;

import com.rabbitmq.client.*;

import java.util.HashMap;
import java.util.Map;

/**
 * 生产者
 *
 * @author 七夜雪
 * @date 2018-12-15 19:56
 */
public class Producer {

    public static void main(String[] args) throws Exception {
        // 1. 创建ConnectionFactory, 并设置属性
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("192.168.72.138");
        factory.setPort(5672);
        factory.setVirtualHost("/");

        // 2. 创建连接
        Connection connection = factory.newConnection();

        // 3. 创建channel
        Channel channel = connection.createChannel();


        String exchangeName = "test_ack_exchange";
        String routingKey = "ack.qiye";

        for (int i = 0; i < 5; i++) {
            // 发送消息
            String msg = "Hello, 七夜雪 " + i;
            Map<String, Object> hearder = new HashMap<String, Object>();
            hearder.put("num", i);
            AMQP.BasicProperties properties = new AMQP.BasicProperties().builder()
                    .contentEncoding("UTF-8")
                    .headers(hearder).build();
            channel.basicPublish(exchangeName, routingKey, true, properties, msg.getBytes());
        }


        // 关闭连接
        channel.close();
        connection.close();

    }

}

Consumer

package com.qiyexue.api.ack;

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

/**
 * 消费者，关闭自动ack
 *
 * @author 七夜雪
 * @date 2018-12-15 20:07
 */
public class Consumer {

    public static void main(String[] args) throws Exception {
        // 1. 创建连接工厂并设置属性
        ConnectionFactory factory = new ConnectionFactory();;
        factory.setHost("192.168.72.138");
        factory.setPort(5672);
        factory.setVirtualHost("/");

        // 2. 创建连接
        Connection connection = factory.newConnection();

        // 3. 创建channel
        Channel channel = connection.createChannel();

        // 4. 声明Exchange
        String exchangeName = "test_ack_exchange";
        String exchangeType = "topic";
        String routingKey = "ack.*";
        channel.exchangeDeclare(exchangeName, exchangeType, true, false, null);

        // 5. 声明消息队列
        String queueName = "test_ack_queue";
        channel.queueDeclare(queueName, true, false, false, null);

        // 6. 绑定队列和Exchange
        channel.queueBind(queueName, exchangeName, routingKey);

        // 7. 设置消费者为自定义的消费者, 将autoAck设置为false
        channel.basicConsume(queueName, false, new MyConsumer(channel));

    }

}