6. 死信队列
6.1. 死信的概念
先从概念解释上搞清楚这个定义，死信，顾名思义就是无法被消费的消息，字面意思可以这样理解，一般来说，producer 将消息投递到 broker 或者直接到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.还有比如说: 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
6.2. 死信的来源
消息 TTL 过期 消息存活时间过期
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. 拒绝应答 不放在队列中 也会在死信中
6.3. 死信实战
6.3.1. 代码架构图
6.3.2. 消息 TTL 过期
生产者代码
public class Producer { private static final String NORMAL_EXCHANGE = "normal_exchange"; public static void main(String[] argv) throws Exception { try (Channel channel = RabbitMqUtils.getChannel()) { channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT); //设置消息的 TTL 时间 newAMQP.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); } } } }
package com.atguigu.rabbitmq.eight; import com.atguigu.rabbitmq.utils.RabbitMqutils; import com.rabbitmq.client.AMQP; import com.rabbitmq.client.Channel; import java.io.IOException; import java.util.concurrent.TimeoutException; /** * 死信队列 生产者 */ public class Producer { //普通交换机 名称 public static final String NORMAL_EXCHANGE="normal_exchange"; public static void main(String[] args) throws IOException, TimeoutException { Channel channel = RabbitMqutils.getChannel(); //死信消息 设置TTl 单位是ms 100000ms=10s AMQP.BasicProperties basicProperties = new AMQP.BasicProperties() .builder().expiration("1000").build(); for (int i = 0; i < 11; i++) { String message="info"+i; channel.basicPublish(NORMAL_EXCHANGE,"zhangsan",basicProperties,message.getBytes()); } } }
消费者 C1 代码(启动之后关闭该消费者 模拟其接收不到消息)
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[] argv) throws Exception { Channel channel = RabbitUtils.getChannel(); //声明死信和普通交换机 类型为 direct channel.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); //死信队列绑定死信交换机与 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"); 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 -> { }); } }
package com.atguigu.rabbitmq.eight; import com.atguigu.rabbitmq.utils.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 * 大小写切换 ctrl+shirft+u */ public class Consumer01 { //普通交换机的名称 public static final String NORMAL_EXCHANGE = "normal_exchange"; //死信交换机的名称 public static final String DEAD_EXCHANGE = "dead_exchange"; //普通队列的名称 public static final String NORMAL_QUEUE = "normal_queue"; //死信队列的名称 public static final String DEAD_QUEUE = "dead_queue"; public static void main(String[] args) throws Exception { Channel channel = RabbitMqutils.getChannel(); //声明死信交换机 类型为direct 1.交换机的名字 2.交换机的类型 channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT); //声明普通交换机 类型为direct channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT); /** * * 生成一个队列 * * 1.队列名称 * * 2.队列中的消息是否持久化 默认消息存储在内存中 否不持久化 （持久化放在磁盘中） * *3.该队列是否只供一个消费者进行消费 是否共享 true 可以多个消费者消费 默认false,只能一个消费者消费 * 4.是否自动删除 最后一个消费者端开连接以后 该队列是否自动删除 true自动删除 false不删除 * 5.其他参数 * */ //声明死信队列 channel.queueDeclare(DEAD_QUEUE, false, false, false, null); //声明普通队列 Map<String, Object> arguments = new HashMap<>(); //过期时间 10s=100000ms // arguments.put("x-message-ttl",100000); //正常队列设置死信交换机 1.值 2.死信交换机名字 arguments.put("x-dead-letter-exchange", DEAD_EXCHANGE); //设置死信RoutingKey arguments.put("x-dead-letter-routing-key", "lisi"); //声明普通队列 channel.queueDeclare(NORMAL_QUEUE, false, false, false, arguments); //绑定普通的交换机与偶有普通的队列 channel.queueBind(NORMAL_QUEUE,NORMAL_EXCHANGE,"zhangsan"); //绑定死信的交换机与偶有死信的队列 channel.queueBind(DEAD_QUEUE,DEAD_EXCHANGE,"lisi"); System.out.println("等待接收消息......."); DeliverCallback deliverCallback = (var1, var2) -> { System.out.println("Consumer01" + new String(var2.getBody(), "utf-8")); }; channel.basicConsume(NORMAL_QUEUE, true, deliverCallback, var1 -> { }); } }
消费者 C2 代码(以上步骤完成后 启动 C2 消费者 它消费死信队列里面的消息)
public class Consumer02 { private static final String DEAD_EXCHANGE = "dead_exchange"; public static void main(String[] argv) throws Exception { Channel channel = RabbitUtils.getChannel(); channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT); String deadQueue = "dead-queue"; channel.queueDeclare(deadQueue, false, false, false, null); channel.queueBind(deadQueue, DEAD_EXCHANGE, "lisi"); System.out.println("等待接收死信队列消息 ........... "); DeliverCallback deliverCallback = (consumerTag, delivery) -> { String message = new String(delivery.getBody(), "UTF-8"); System.out.println("Consumer02 接收死信队列的消息" + message); }; channel.basicConsume(deadQueue, true, deliverCallback, consumerTag -> { }); } }
package com.atguigu.rabbitmq.eight; import com.atguigu.rabbitmq.utils.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 * 大小写切换 ctrl+shirft+u */ public class Consumer02 { //死信队列的名称 public static final String DEAD_QUEUE = "dead_queue"; public static void main(String[] args) throws Exception { Channel channel = RabbitMqutils.getChannel(); System.out.println("等待接收消息......."); DeliverCallback deliverCallback = (var1, var2) -> { System.out.println("Consumer02" + new String(var2.getBody(), "utf-8")); }; channel.basicConsume(DEAD_QUEUE, true, deliverCallback, var1 -> { }); } }
6.3.3. 队列达到最大长度
1. 消息生产者代码去掉 TTL 属性
public class Producer { private static final String NORMAL_EXCHANGE = "normal_exchange"; public static void main(String[] argv) throws Exception { try (Channel channel = RabbitMqUtils.getChannel()) { channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT); //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); } } } }
2. C1 消费者修改以下代码(启动之后关闭该消费者 模拟其接收不到消息
注意此时需要把原先队列删除 因为参数改变了
- C2 消费者代码不变(启动 C2 消费者)
6.3.4. 消息被拒
- 消息生产者代码同上生产者一致
- C1 消费者代码(启动之后关闭该消费者 模拟其接收不到消息)
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[] argv) throws Exception { Channel channel = RabbitUtils.getChannel(); //声明死信和普通交换机 类型为 direct channel.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); //死信队列绑定死信交换机与 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"); 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); } }; boolean autoAck = false; channel.basicConsume(normalQueue, autoAck, deliverCallback, consumerTag -> { }); } }
- C2 消费者代码不变
启动消费者 1 然后再启动消费者 2
上面3个部分内容代码整理 如下 ：
C1
package com.atguigu.rabbitmq.eight; import com.atguigu.rabbitmq.utils.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 * 大小写切换 ctrl+shirft+u */ public class Consumer01 { //普通交换机的名称 public static final String NORMAL_EXCHANGE = "normal_exchange"; //死信交换机的名称 public static final String DEAD_EXCHANGE = "dead_exchange"; //普通队列的名称 public static final String NORMAL_QUEUE = "normal_queue"; //死信队列的名称 public static final String DEAD_QUEUE = "dead_queue"; public static void main(String[] args) throws Exception { Channel channel = RabbitMqutils.getChannel(); //声明死信交换机 类型为direct 1.交换机的名字 2.交换机的类型 channel.exchangeDeclare(DEAD_EXCHANGE, BuiltinExchangeType.DIRECT); //声明普通交换机 类型为direct channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT); /** * * 生成一个队列 * * 1.队列名称 * * 2.队列中的消息是否持久化 默认消息存储在内存中 否不持久化 （持久化放在磁盘中） * *3.该队列是否只供一个消费者进行消费 是否共享 true 可以多个消费者消费 默认false,只能一个消费者消费 * 4.是否自动删除 最后一个消费者端开连接以后 该队列是否自动删除 true自动删除 false不删除 * 5.其他参数 * */ //声明普通队列 Map<String, Object> arguments = new HashMap<>(); //过期时间 10s=100000ms // arguments.put("x-message-ttl",100000); //正常队列设置死信交换机 1.值 2.死信交换 机名字 arguments.put("x-dead-letter-exchange", DEAD_EXCHANGE); //设置死信RoutingKey arguments.put("x-dead-letter-routing-key", "lisi"); //设置正常队列长度的限制 //arguments.put("x-max-length",6); //声明普通队列 channel.queueDeclare(NORMAL_QUEUE, false, false, false,arguments); //声明死信队列 channel.queueDeclare(DEAD_QUEUE, false, false, false, null); //绑定普通的交换机与偶有普通的队列 channel.queueBind(NORMAL_QUEUE,NORMAL_EXCHANGE,"zhangsan"); //绑定死信的交换机与偶有死信的队列 channel.queueBind(DEAD_QUEUE,DEAD_EXCHANGE,"lisi"); System.out.println("等待接收消息......."); DeliverCallback deliverCallback = (var1, var2) -> { String msg= new String(var2.getBody(), "utf-8"); if (msg.equals("info5")){ System.out.println("Consumer01接受的消息是"+msg+"消息是被拒绝的"); // 1.获取到值 2.不放回普通队列 channel.basicReject(var2.getEnvelope().getDeliveryTag(),false ); }else { System.out.println("Consumer01接受的消息是" +msg); channel.basicReject(var2.getEnvelope().getDeliveryTag(),false ); } }; // channel.basicConsume(NORMAL_QUEUE, true, deliverCallback, var1 -> {}); channel.basicConsume(NORMAL_QUEUE, false, deliverCallback, var1 -> {}); } }
C2
package com.atguigu.rabbitmq.eight; import com.atguigu.rabbitmq.utils.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 * 大小写切换 ctrl+shirft+u */ public class Consumer02 { //死信队列的名称 public static final String DEAD_QUEUE = "dead_queue"; public static void main(String[] args) throws Exception { Channel channel = RabbitMqutils.getChannel(); System.out.println("等待接收消息......."); DeliverCallback deliverCallback = (var1, var2) -> { System.out.println("Consumer02" + new String(var2.getBody(), "utf-8")); }; channel.basicConsume(DEAD_QUEUE, true, deliverCallback, var1 -> { }); } }
生产者
package com.atguigu.rabbitmq.eight; import com.atguigu.rabbitmq.utils.RabbitMqutils; import com.rabbitmq.client.AMQP; import com.rabbitmq.client.Channel; import java.io.IOException; import java.util.concurrent.TimeoutException; /** * 死信队列 生产者 */ public class Producer { //普通交换机 名称 public static final String NORMAL_EXCHANGE="normal_exchange"; public static void main(String[] args) throws IOException, TimeoutException { Channel channel = RabbitMqutils.getChannel(); //死信消息 设置TTl 单位是ms 100000ms=10s 过期时间 // AMQP.BasicProperties basicProperties = // new AMQP.BasicProperties() // .builder().expiration("1000").build(); for (int i = 1; i < 11; i++) { String message="info"+i; channel.basicPublish(NORMAL_EXCHANGE,"zhangsan",null,message.getBytes()); // channel.basicPublish(NORMAL_EXCHANGE,"zhangsan",basicProperties,message.getBytes()); System.out.println("生产者发送消息"+message); } } }
