jsp做的当当网站的文档,电商课程,vi设计案例ppt,wordpress 字体大小文章目录 一、死信的概念二、死信的来源三、实战1、消息 TTL 过期2、队列达到最大长度3、消息被拒 总结 一、死信的概念
先从概念解释上搞清楚这个定义#xff0c;死信#xff0c;顾名思义就是无法被消费的消息#xff0c;字面意思可以这样理解#xff0c;一般来说#x… 文章目录 一、死信的概念二、死信的来源三、实战1、消息 TTL 过期2、队列达到最大长度3、消息被拒 总结 一、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。
二、死信的来源 消息 TTL 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 requeuefalse.
三、实战 1、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AMQP.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 messageinfoi;channel.basicPublish(NORMAL_EXCHANGE, zhangsan, properties, message.getBytes());System.out.println(生产者发送消息:message);}}}
}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 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);//死信队列绑定死信交换机与 routingkeychannel.queueBind(deadQueue, DEAD_EXCHANGE, lisi);//正常队列绑定死信队列信息MapString, 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 - {});}
}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 - {});}
}2、队列达到最大长度
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 messageinfoi;channel.basicPublish(NORMAL_EXCHANGE,zhangsan,null, message.getBytes());System.out.println(生产者发送消息:message);}}}
}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)
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 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);//死信队列绑定死信交换机与 routingkeychannel.queueBind(deadQueue, DEAD_EXCHANGE, lisi);//正常队列绑定死信队列信息MapString, 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);//设置正常队列长度限制params.put(x-max-length,6);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 - {});}
}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
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 - {});}
}3、消息被拒
消息生产者代码
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);//该信息是用作演示队列个数限制for (int i 1; i 11 ; i) {String messageinfoi;channel.basicPublish(NORMAL_EXCHANGE,zhangsan,null, message.getBytes());System.out.println(生产者发送消息:message);}}}
}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 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);//死信队列绑定死信交换机与 routingkeychannel.queueBind(deadQueue, DEAD_EXCHANGE, lisi);//正常队列绑定死信队列信息MapString, 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
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 - {});}
}启动消费者 1 然后再启动消费者 2 总结
以上就是RabbitMQ之死信队列的相关知识点希望对你有所帮助。
