RabbitMQ API（七） 消费端限流

限流步骤

• autoAck 设置为 false；
• void basicQos(int prefetchSize, int prefetchCount, boolean global) 具体设置限流参数；
• 手动 ACK；

消费者

package com.bfxy.rabbitmq.api.limit;

import com.bfxy.rabbitmq.Application;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.QueueingConsumer;
import com.rabbitmq.client.QueueingConsumer.Delivery;

public class Consumer {
    
    public static void main(String[] args) throws Exception {
        
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost(Application.HOST);
        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);

        /**
         * prefetchSize: 消息大小限制；
         * prefetchCount: 消息数量限制；
         * global: false - Consumer级别；
         */
        channel.basicQos(0, 1, false);
        channel.basicConsume(queueName, false, new MyConsumer(channel));
        
    }

}

• 如果 channel.basicAck(envelope.getDeliveryTag(), false); 注释掉的话，消费者只能消费一条消息；

package com.bfxy.rabbitmq.api.limit;

import java.io.IOException;

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

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));
        
        channel.basicAck(envelope.getDeliveryTag(), false);
    }

}

生产者

package com.bfxy.rabbitmq.api.limit;

import com.bfxy.rabbitmq.Application;
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(Application.HOST);
        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());
        }
        
    }

}