RabbitMQ_03_消息模式2-阿南达文事网

RabbitMQ_03_消息模式2

文章目录

- 消费端限流
- 消息的ACK与重回队列
- TTL消息
- 死信队列

消费端限流

什么是消费端的限流？
假设一个场景，首先，我们RabbitMQ服务器有上万条未处理的消息，我们随便打开一个消费者客户端，会出现下面情况：
巨量的消息瞬间全部推送过来，但是我们单个客户端无法同时处理这么多数据！

消费端限流RabbitMQ提供的解决方案
RabbitMQ提供了一种qos（服务质量保证）功能，即在非自动确认消息的前提下，如果一定数目的消息（通过基于Consumer或者Channel设置Qos的值）未被确认前，不进行消费新的消息
Void BasicQos(uint prefetchSize, ushort prefetchCount, bool global);
prefetchSize：0 不限制消息大小
prefetchSize：会告诉RabbitMQ不要同时给一个消费者推送多于N个消息，即一旦有N个消息还没有ack，则该Consumer将block（阻塞）掉，直到有消息ack
Global：true\false是否将上面设置应用于Channel；简单来说，就是上面限制是Channel级别的还是Consumer级别

注意：
prefetchSize和global这两项，RabbitMQ没有实现，暂且不研究；
prefetch_count在no_ask=false的情况下生效，即在自动应答的情况下，这两个值是不生效的；

自定义消费端代码

package com.caoluo.rabbitmqapi.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;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 10:46*/
public class MyConsumer extends DefaultConsumer {private Channel channel ;public MyConsumer(Channel channel) {super(channel);this.channel = channel;}@Overridepublic 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);}}

消费端代码

package com.caoluo.rabbitmqapi.limit;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 10:46*/
public class Consumer {public static void main(String[] args) throws Exception {ConnectionFactory connectionFactory = new ConnectionFactory();connectionFactory.setHost("192.168.147.146");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 falsechannel.basicQos(0, 1, false);channel.basicConsume(queueName, false, new MyConsumer(channel));}
}

提供方代码

package com.caoluo.rabbitmqapi.limit;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 10:47*/
public class Producer {public static void main(String[] args) throws Exception {ConnectionFactory connectionFactory = new ConnectionFactory();connectionFactory.setHost("192.168.147.146");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());}}
}

消息的ACK与重回队列

消费端手工ACK与NACK
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，那么我们就需要手工进行ACK，保障消费端消费成功！

消费端的重回队列
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！
一般我们在实际应用中，都会关闭重回队列，也就是设置为False；因为重回队列消息有很大概率依然会处理失败！

自定义消费者代码

package com.caoluo.rabbitmqapi.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;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 11:03*/
public class MyConsumer extends DefaultConsumer {private Channel channel ;public MyConsumer(Channel channel) {super(channel);this.channel = channel;}@Overridepublic 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) {
//            手动签收，重回队列channel.basicNack(envelope.getDeliveryTag(), false, true);} else {channel.basicAck(envelope.getDeliveryTag(), false);}}}

消费者代码

package com.caoluo.rabbitmqapi.ack;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 11:04*/
public class Consumer {public static void main(String[] args) throws Exception {ConnectionFactory connectionFactory = new ConnectionFactory();connectionFactory.setHost("192.168.147.146");connectionFactory.setPort(5672);connectionFactory.setVirtualHost("/");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);// 手工签收 必须要关闭 autoAck = falsechannel.basicConsume(queueName, false, new MyConsumer(channel));}
}

生产者代码

package com.caoluo.rabbitmqapi.ack;import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;import java.util.HashMap;
import java.util.Map;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 11:04*/
public class Producer {public static void main(String[] args) throws Exception {ConnectionFactory connectionFactory = new ConnectionFactory();connectionFactory.setHost("192.168.147.146");connectionFactory.setPort(5672);connectionFactory.setVirtualHost("/");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());}}
}

TTL消息

TTL
TTL是Time To Live的缩写，也就是生存时间
RabbitMQ支持消息的过期时间，在消息发送时可以进行指定
RabbitMQ支持队列的过期时间，从消息入队列开始计算，只要超过了队列的超时时间配置，那么消息自动的清除

纯控制台操作（演示TTL队列消息特点）
针对队列，只要是这个队列的消息，就只有这么长的存活时间

注意：主要针对消息设置，跟交换机、队列、消费者设置毫无关系

消费端代码

package com.caoluo.rabbitmqapi.ttl;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.QueueingConsumer;import java.util.Map;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 11:15*/
public class Consumer {public static void main(String[] args) throws Exception {//1 创建一个ConnectionFactory, 并进行配置ConnectionFactory connectionFactory = new ConnectionFactory();connectionFactory.setHost("192.168.147.146");connectionFactory.setPort(5672);connectionFactory.setVirtualHost("/");//2 通过连接工厂创建连接Connection connection = connectionFactory.newConnection();//3 通过connection创建一个ChannelChannel channel = connection.createChannel();//4 声明（创建）一个队列String queueName = "test001";channel.queueDeclare(queueName, true, false, false, null);//5 创建消费者QueueingConsumer queueingConsumer = new QueueingConsumer(channel);//6 设置Channelchannel.basicConsume(queueName, true, queueingConsumer);while(true){//7 获取消息QueueingConsumer.Delivery delivery = queueingConsumer.nextDelivery();String msg = new String(delivery.getBody());System.err.println("消费端: " + msg);Map<String, Object> headers = delivery.getProperties().getHeaders();System.err.println("headers get my1 value: " + headers.get("my1"));//Envelope envelope = delivery.getEnvelope();}}
}

生产端代码

package com.caoluo.rabbitmqapi.ttl;import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;import java.util.HashMap;
import java.util.Map;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 11:16*/
public class Procuder {public static void main(String[] args) throws Exception {//1 创建一个ConnectionFactory, 并进行配置ConnectionFactory connectionFactory = new ConnectionFactory();connectionFactory.setHost("192.168.147.146");connectionFactory.setPort(5672);connectionFactory.setVirtualHost("/");//2 通过连接工厂创建连接Connection connection = connectionFactory.newConnection();//3 通过connection创建一个ChannelChannel channel = connection.createChannel();Map<String, Object> headers = new HashMap<>();headers.put("my1", "111");headers.put("my2", "222");AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder().deliveryMode(2).contentEncoding("UTF-8").expiration("10000").headers(headers).build();//4 通过Channel发送数据for(int i=0; i < 5; i++){String msg = "Hello RabbitMQ!";//1 exchange   2 routingKeychannel.basicPublish("", "test001", properties, msg.getBytes());}//5 记得要关闭相关的连接channel.close();connection.close();}
}

死信队列

死信队列：DLX，Dead-Letter-Exchange
利用DLX，当消息在一个队列中变成死信（dead message）之后，它能被重新publish到另一个Exchange，这个Exchange就是DLX

消息变成死信有以下几种情况
消息被拒绝（basic.reject/basic.nack）并且requeue=false
消息TTL过期
队列达到最大长度

死信队列的特点
DLX也是一个正常的Exchange，和一般的Exchange没有区别，它能在任何的队列上被指定，实际上就是设置某个队列的属性；
当这个队列中有死信时，RabbitMQ就会自动的将这个消息重新发布到设置的Exchange上去，进而被路由到另一个队列；
可以监听这个队列中消息做相应的处理，这个特性可以弥补RabbitMQ3.0以前支持的immediate参数的功能；

死信队列设置
首先需要设置死信队列的Exchange和Queue，然后进行绑定：
Exchange：dlx.exchange
Queue：dlx.queue
RoutingKey：#
然后我们进行正常声明交换机、队列、绑定，只不过我们需要在队列加上一个参数即可：
Arguments.put(“x-dead-letter-exchange”,”dlx.exchange”)；
这样消息在过期、requeue、队列在达到最大长度时，消息就可以直接路由到死信队列！

自定义消费端

package com.caoluo.rabbitmqapi.dlx;import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;import java.io.IOException;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 11:37*/
public class MyConsumer extends DefaultConsumer {public MyConsumer(Channel channel) {super(channel);}@Overridepublic 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));}}

消费端代码

package com.caoluo.rabbitmqapi.dlx;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;import java.util.HashMap;
import java.util.Map;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 11:38*/
public class Consumer {public static void main(String[] args) throws Exception {ConnectionFactory connectionFactory = new ConnectionFactory();connectionFactory.setHost("192.168.147.146");connectionFactory.setPort(5672);connectionFactory.setVirtualHost("/");Connection connection = connectionFactory.newConnection();Channel channel = connection.createChannel();// 这就是一个普通的交换机 和 队列 以及路由String exchangeName = "test_dlx_exchange";String routingKey = "dlx.#";String queueName = "test_dlx_queue";channel.exchangeDeclare(exchangeName, "topic", true, false, null);Map<String, Object> agruments = new HashMap<String, Object>();agruments.put("x-dead-letter-exchange", "dlx.exchange");//这个agruments属性，要设置到声明队列上channel.queueDeclare(queueName, true, false, false, agruments);channel.queueBind(queueName, exchangeName, routingKey);//要进行死信队列的声明:channel.exchangeDeclare("dlx.exchange", "topic", true, false, null);channel.queueDeclare("dlx.queue", true, false, false, null);channel.queueBind("dlx.queue", "dlx.exchange", "#");channel.basicConsume(queueName, true, new MyConsumer(channel));}
}

生产端代码

package com.caoluo.rabbitmqapi.dlx;import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;/*** @author caoluo* @site www.caoluo.com* @company* @create  2019-12-07 11:38*/
public class Producer {public static void main(String[] args) throws Exception {ConnectionFactory connectionFactory = new ConnectionFactory();connectionFactory.setHost("192.168.147.146");connectionFactory.setPort(5672);connectionFactory.setVirtualHost("/");Connection connection = connectionFactory.newConnection();Channel channel = connection.createChannel();String exchange = "test_dlx_exchange";String routingKey = "dlx.save";String msg = "Hello RabbitMQ DLX Message";for(int i =0; i<1; i ++){AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder().deliveryMode(2).contentEncoding("UTF-8").expiration("10000").build();channel.basicPublish(exchange, routingKey, true, properties, msg.getBytes());}}
}

RabbitMQ_03_消息模式2