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
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
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 -> {
});
}
}
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);
}
}
}
}
注意此时需要把原先队列删除 因为参数改变了
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 -> { });
}
}
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);
}
}
}