消息中間件--RabbitMQ ---進階特性之消費端ACK與重回隊列

什麼是消費端的ACK和重回隊列？

消費端的手工ACK和NACK

1. 消費端進行消費的時候,如果由于業務異常我們可以進行日志的記錄,然後進行補償
2. 如果由于伺服器當機等嚴重問題,那我們就需要手工進行ACK保障費端消費成功!

消費端重回隊列

1. 消費端重回隊列是為了對沒有處理成功的消息,把消息重新會遞給Broker
2. 一般我們在實際應用中,都會關閉重回隊列,也就是設定為 False

生産端代碼

package com.bfxy.rabbitmq.api.ack;

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

import com.rabbitmq.client.AMQP;
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("localhost");
//		connectionFactory.setHost("192.168.43.223");
		connectionFactory.setPort(5672);
		connectionFactory.setVirtualHost("/");
		connectionFactory.setUsername("guest");
		connectionFactory.setPassword("guest");
		
		Connection connection = connectionFactory.newConnection();
		Channel channel = connection.createChannel();
		
		String exchange = "test_ack_exchange";
		String routingKey = "ack.save";
		
		for(int i =0; i<5; i ++){
			
			Map<String, Object> headers = new HashMap<String, Object>();
			headers.put("num", i);
			
			AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder()
					.deliveryMode(2)
					.contentEncoding("UTF-8")
					.headers(headers)
					.build();
			String msg = "Hello RabbitMQ ACK Message " + i;
			channel.basicPublish(exchange, routingKey, true, properties, msg.getBytes());
		}
		
	}
}

           

消費者

package com.bfxy.rabbitmq.api.ack;

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("localhost");
//		connectionFactory.setHost("192.168.43.223");
		connectionFactory.setPort(5672);
		connectionFactory.setVirtualHost("/");
		connectionFactory.setUsername("guest");
		connectionFactory.setPassword("guest");
		
		Connection connection = connectionFactory.newConnection();
		Channel channel = connection.createChannel();
		
		
		String exchangeName = "test_ack_exchange";
		String queueName = "test_ack_queue";
		String routingKey = "ack.#";
		
		channel.exchangeDeclare(exchangeName, "topic", true, false, null);
		channel.queueDeclare(queueName, true, false, false, null);
		channel.queueBind(queueName, exchangeName, routingKey);
		
		// 手工簽收 必須要關閉 autoAck = false
		channel.basicConsume(queueName, false, new MyConsumer(channel));
		
		
	}
}

           

package com.bfxy.rabbitmq.api.ack;

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("body: " + new String(body));
		try {
			Thread.sleep(2000);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		if((Integer)properties.getHeaders().get("num") == 0) {
			channel.basicNack(envelope.getDeliveryTag(), false, true);
		} else {
			channel.basicAck(envelope.getDeliveryTag(), false);
		}
		
	}
}

           

運作結果：

重回隊列，回到隊列末尾

有一條消息沒有被消費