RabbitMQ的消费限流

高并发场景下生产者产生大量的消息，对于巨量的消息瞬间推送消费端无法处理

rabbitmq提供了服务质量保障功能，即在非自动确认消息的前提下，如果一定数目的消息未被确认，不进行消费新的消息。

使用 basicqos方法。在消费端进行使用。 0 1 false
prefetSize：0
prefetCount：这个值一般在设置为非自动ack的情况下生效，一般大小为1
global： true是channel级别， false是消费者级别
注意：我们要使用非自动ack

消费者：

package com.flying.rabbitmq.api.limit;

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("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();
        
        
        String exchangeName = "test_qos_exchange";
        String queueName = "test_qos_queue";
        String routingKey = "qos.#";
        
        channel.exchangeDeclare(exchangeName, "topic", true, false, null);
        channel.queueDeclare(queueName, true, false, false, null);
        channel.queueBind(queueName, exchangeName, routingKey);
        
        //1 限流方式  第一件事就是 autoAck设置为 false
        
        channel.basicQos(0, 1, false);
        
        channel.basicConsume(queueName, false, new MyConsumer(channel));
        
        
    }
}

自定义消费监听

package com.flying.rabbitmq.api.limit;

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 {


    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.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));


        // TODO 第二个参数设置为false，因为消费者设置的为prefetCount1
        //2手工签收
        channel.basicAck(envelope.getDeliveryTag(), false);
        
    }


}

生产者：

package com.flying.rabbitmq.api.limit;

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("127.0.0.1");
        connectionFactory.setPort(5672);
        connectionFactory.setVirtualHost("/");
        
        Connection connection = connectionFactory.newConnection();
        Channel channel = connection.createChannel();
        
        String exchange = "test_qos_exchange";
        String routingKey = "qos.save";
        
        String msg = "Hello RabbitMQ QOS Message";
        
        for(int i =0; i<5; i ++){
            channel.basicPublish(exchange, routingKey, true, null, msg.getBytes());
        }
        
    }
}