矿业公司网站源码新媒体运营培训课程
目录
死信的概念
死信的来源
死信实战
死信之TTl
死信之最大长度
死信之消息被拒
死信的概念
死信，顾名思义就是无法被消费的消息，一般来说，producer 将消息投递到 broker 或直接到queue 里了，consumer 从 queue 取出消息进行消费，但某些时候由于特定的原因导致 queue 中的某些消息无法被消费，这样的消息如果没有后续的处理，就变成了死信，有死信自然就有了死信队列。
应用场景：为了保证订单业务的消息数据不丢失，需要使用到 RabbitMQ 的死信队列机制，当消息消费发生异常时，将消息投入死信队列中；还有用户在商城下单成功并点击去支付后在指定时间未支付时自动失效。
死信的来源
-
消息 TTL 过期
TTL是Time To Live的缩写, 也就是生存时间
-
队列达到最大长度
队列满了，无法再添加数据到 mq 中
-
消息被拒绝
(basic.reject 或 basic.nack) 并且 requeue=false
死信实战
死信之TTl
消费者 C1：
package com.qcby.sixin;import com.qcby.util.RabbitMqUtils;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;import java.util.HashMap;
import java.util.Map;/*** 死信队列 - 消费者1**/
public class Consumer01 {//普通交换机名称private static final String NORMAL_EXCHANGE = "normal_exchange";//死信交换机名称private static final String DEAD_EXCHANGE = "dead_exchange";public static void main(String[] args) throws Exception {Channel channel = RabbitMqUtils.getChannel();//声明死信和普通交换机 类型为 directchannel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);//声明死信队列String deadQueue = "dead-queue";channel.queueDeclare(deadQueue, false, false, false, null);//死信队列绑定：队列、交换机、路由键（routingKey）channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");//正常队列绑定死信队列信息Map<String, Object> params = new HashMap<>();//正常队列设置死信交换机，参数 key 是固定值params.put("x-dead-letter-exchange", DEAD_EXCHANGE);//正常队列设置死信 routing-key，参数 key 是固定值params.put("x-dead-letter-routing-key", "lisi");//正常队列String normalQueue = "normal-queue";channel.queueDeclare(normalQueue, false, false, false, params);channel.queueBind(normalQueue, NORMAL_EXCHANGE, "zhangsan");System.out.println("等待接收消息........... ");DeliverCallback deliverCallback = (consumerTag, delivery) -> {String message = new String(delivery.getBody(), "UTF-8");System.out.println("Consumer01 接收到消息" + message);};channel.basicConsume(normalQueue, true, deliverCallback, consumerTag -> {});}}
生产者：
package com.qcby.sixin;import com.qcby.util.RabbitMqUtils;
import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;public class Producer {private static final String NORMAL_EXCHANGE = "normal_exchange";public static void main(String[] argv) throws Exception {Channel channel = RabbitMqUtils.getChannel();channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);//设置消息的 TTL 时间 10sAMQP.BasicProperties properties = new AMQP.BasicProperties().builder().expiration("10000").build();//该信息是用作演示队列个数限制for (int i = 1; i < 11; i++) {String message = "info" + i;channel.basicPublish(NORMAL_EXCHANGE, "zhangsan", properties, message.getBytes());System.out.println("生产者发送消息:" + message);}}
}
消费者 C2：
package com.qcby.sixin;import com.qcby.util.RabbitMqUtils;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;public class Consumer02 {//死信交换机名称private static final String DEAD_EXCHANGE = "dead_exchange";public static void main(String[] args) throws Exception {Channel channel = RabbitMqUtils.getChannel();//声明交换机channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);//声明队列String deadQueue = "dead-queue";channel.queueDeclare(deadQueue, false, false, false, null);channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");System.out.println("等待接收死信消息........... ");DeliverCallback deliverCallback = (consumerTag, delivery) -> {String message = new String(delivery.getBody(), "UTF-8");System.out.println("Consumer02 接收到消息" + message);};channel.basicConsume(deadQueue, true, deliverCallback, consumerTag -> {});}
}
启动 C1 ，之后关闭消费者，模拟其接收不到消息，再启动 Producer：
启动 C2 消费者，它消费死信队列里面的消息：
死信之最大长度
消费者 C1：
package com.qcby.sixin.two;import com.qcby.util.RabbitMqUtils;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;import java.util.HashMap;
import java.util.Map;/*** 死信队列 - 消费者1**/
public class Consumer01 {//普通交换机名称private static final String NORMAL_EXCHANGE = "normal_exchange";//死信交换机名称private static final String DEAD_EXCHANGE = "dead_exchange";public static void main(String[] args) throws Exception {Channel channel = RabbitMqUtils.getChannel();//声明死信和普通交换机 类型为 directchannel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);//声明死信队列String deadQueue = "dead-queue";channel.queueDeclare(deadQueue, false, false, false, null);//死信队列绑定：队列、交换机、路由键（routingKey）channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");//正常队列绑定死信队列信息Map<String, Object> params = new HashMap<>();//正常队列设置死信交换机，参数 key 是固定值params.put("x-dead-letter-exchange", DEAD_EXCHANGE);//正常队列设置死信 routing-key，参数 key 是固定值params.put("x-dead-letter-routing-key", "lisi");//设置正常队列的长度限制params.put("x-max-length",6);//正常队列String normalQueue = "normal-queue";channel.queueDeclare(normalQueue, false, false, false, params);channel.queueBind(normalQueue, NORMAL_EXCHANGE, "zhangsan");System.out.println("等待接收消息........... ");DeliverCallback deliverCallback = (consumerTag, delivery) -> {String message = new String(delivery.getBody(), "UTF-8");System.out.println("Consumer01 接收到消息" + message);};channel.basicConsume(normalQueue, true, deliverCallback, consumerTag -> {});}}
生产者：
package com.qcby.sixin.two;import com.qcby.util.RabbitMqUtils;
import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;public class Producer {private static final String NORMAL_EXCHANGE = "normal_exchange";public static void main(String[] argv) throws Exception {Channel channel = RabbitMqUtils.getChannel();//该信息是用作演示队列个数限制for (int i = 1; i < 11; i++) {String message = "info" + i;channel.basicPublish(NORMAL_EXCHANGE, "zhangsan", null, message.getBytes());System.out.println("生产者发送消息:" + message);}}
}
消费者 C2：
package com.qcby.sixin.two;import com.qcby.util.RabbitMqUtils;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;public class Consumer02 {//死信交换机名称private static final String DEAD_EXCHANGE = "dead_exchange";public static void main(String[] args) throws Exception {Channel channel = RabbitMqUtils.getChannel();//声明交换机channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);//声明队列String deadQueue = "dead-queue";channel.queueDeclare(deadQueue, false, false, false, null);channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");System.out.println("等待接收死信消息........... ");DeliverCallback deliverCallback = (consumerTag, delivery) -> {String message = new String(delivery.getBody(), "UTF-8");System.out.println("Consumer02 接收到消息" + message);};channel.basicConsume(deadQueue, true, deliverCallback, consumerTag -> {});}
}
死信之消息被拒
拒收消息 "info5"
消费者 C1：
package com.qcby.sixin.three;import com.qcby.util.RabbitMqUtils;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;import java.util.HashMap;
import java.util.Map;/*** 死信队列 - 消费者1**/
public class Consumer01 {//普通交换机名称private static final String NORMAL_EXCHANGE = "normal_exchange";//死信交换机名称private static final String DEAD_EXCHANGE = "dead_exchange";public static void main(String[] args) throws Exception {Channel channel = RabbitMqUtils.getChannel();//声明死信和普通交换机 类型为 directchannel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);//声明死信队列String deadQueue = "dead-queue";channel.queueDeclare(deadQueue, false, false, false, null);//死信队列绑定：队列、交换机、路由键（routingKey）channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");//正常队列绑定死信队列信息Map<String, Object> params = new HashMap<>();//正常队列设置死信交换机，参数 key 是固定值params.put("x-dead-letter-exchange", DEAD_EXCHANGE);//正常队列设置死信 routing-key，参数 key 是固定值params.put("x-dead-letter-routing-key", "lisi");//正常队列String normalQueue = "normal-queue";channel.queueDeclare(normalQueue, false, false, false, params);channel.queueBind(normalQueue, NORMAL_EXCHANGE, "zhangsan");System.out.println("等待接收消息........... ");DeliverCallback deliverCallback = (consumerTag, delivery) -> {String message = new String(delivery.getBody(), "UTF-8");if (message.equals("info5")) {System.out.println("Consumer01 接收到消息" + message + "并拒绝签收该消息");//requeue 设置为 false 代表拒绝重新入队 该队列如果配置了死信交换机将发送到死信队列中channel.basicReject(delivery.getEnvelope().getDeliveryTag(), false);} else {System.out.println("Consumer01 接收到消息" + message);channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);}};//开启手动应答channel.basicConsume(normalQueue, false, deliverCallback, consumerTag -> {});}}
生产者：
package com.qcby.sixin.three;import com.qcby.util.RabbitMqUtils;
import com.rabbitmq.client.Channel;public class Producer {private static final String NORMAL_EXCHANGE = "normal_exchange";public static void main(String[] argv) throws Exception {Channel channel = RabbitMqUtils.getChannel();//该信息是用作演示队列个数限制for (int i = 1; i < 11; i++) {String message = "info" + i;channel.basicPublish(NORMAL_EXCHANGE, "zhangsan", null, message.getBytes());System.out.println("生产者发送消息:" + message);}}
}
消费者 C2：
package com.qcby.sixin.three;import com.qcby.util.RabbitMqUtils;
import com.rabbitmq.client.BuiltinExchangeType;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.DeliverCallback;public class Consumer02 {//死信交换机名称private static final String DEAD_EXCHANGE = "dead_exchange";public static void main(String[] args) throws Exception {Channel channel = RabbitMqUtils.getChannel();//声明交换机channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT);//声明队列String deadQueue = "dead-queue";channel.queueDeclare(deadQueue, false, false, false, null);channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi");System.out.println("等待接收死信消息........... ");DeliverCallback deliverCallback = (consumerTag, delivery) -> {String message = new String(delivery.getBody(), "UTF-8");System.out.println("Consumer02 接收到消息" + message);};channel.basicConsume(deadQueue, true, deliverCallback, consumerTag -> {});}
}
