死信队列
死信：顾名思义就是无法被消费的消息，一般情况下，product将消息投递到broker或者直接到queue里，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，就变成死信，有死信自然就有死信队列。
一般应用场景：为了保证订单业务中的消息数据不丢失，需要使用rabbitMQ的死信队列机制，当消息消费发生异常的时候，将消息投入死信队列中，还有比如说：用户在商场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
- 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
消息TTL过期
/*
死信队列
之生产者代码
*/
public class Product {
//普通交换机的名称
public static final String NORMAL_EXCHANGE = "normal_exchange";
public static void main(String[] args) throws IOException, TimeoutException {
Channel channel = GetConnection.getChannel();
//死信消息，设置TTL时间
AMQP.BasicProperties properties =
new AMQP.BasicProperties()
.builder().expiration("10000").build();
for (int i = 0; i < 11; i++) {
String message = "info "+ i;
channel.basicPublish(NORMAL_EXCHANGE,"zhangsan",properties,message.getBytes());
}
}
}
/*
死信
消费者
*/
public class Consumer01 {
//普通交换机的名称
private static final String NORMAL_EXCHANGE = "normal_exchange";
//死信交换机的名称
private static final String DEAD_EXCHANGE = "dead_exchange";
//普通队列名称
private static final String NORMAL_QUEUE = "normal_queue";
//死信队列名称
private static final String DEAD_QUEUE = "dead_queue";
public static void main(String[] args) throws IOException, TimeoutException {
Channel channel = GetConnection.getChannel();
//声明死信和普通交换机类型 direct
channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
channel.exchangeDeclare(DEAD_EXCHANGE,BuiltinExchangeType.DIRECT);
// 普通队列
Map<String,Object> argument = new HashMap<>();
//过期时间10秒过期 可以不设置，可以交给队列自动去
// argument.put("x-message-ttl",100000);
//正常队列设置死信交换机
argument.put("x-dead-lettle-exchange",DEAD_EXCHANGE);
//设置死信RoutingKey
argument.put("x-dead-lettle-routing-key","lisi");
channel.queueDeclare(NORMAL_QUEUE,false,false,false,argument);
///
//声名死信队列
channel.queueDeclare(DEAD_QUEUE,false,false,false,null);
//绑定普通交换机和普通队列
channel.queueBind(NORMAL_QUEUE,NORMAL_EXCHANGE,"zhangsan");
//绑定死信的交换机与死信队列
channel.queueBind(DEAD_QUEUE,DEAD_EXCHANGE,"lisi");
System.out.println("等待接受......");
//绑定死信的交换机和死信的对列
DeliverCallback deliverCallback = (consumer,message)->{
System.out.println("Consumer 01接受到消息是：" + new String(message.getBody(),"UTF-8"));
};
channel.basicConsume(NORMAL_QUEUE,true,deliverCallback,consumer->{});
}
}
public class Consumer02 {
//死信队列名称
private static final String DEAD_QUEUE = "dead_queue";
public static void main(String[] args) throws IOException, TimeoutException {
Channel channel = GetConnection.getChannel();
System.out.println("等待接受......");
//绑定死信的交换机和死信的对列
DeliverCallback deliverCallback = (consumer,message)->{
System.out.println("Consumer 02接受到消息是：" + new String(message.getBody(),"UTF-8"));
};
channel.basicConsume(DEAD_QUEUE,true,deliverCallback,consumer->{});
}
}
解决进不去死信队列的原因了，就是我没给他把过期时间值传进去，导致出现问题。
队列达到最大长度
消息生成者代码去掉TTL属性。
public class Consumer01 {
//普通交换机的名称
private static final String NORMAL_EXCHANGE = "normal_exchange";
//死信交换机的名称
private static final String DEAD_EXCHANGE = "dead_exchange";
//普通队列名称
private static final String NORMAL_QUEUE = "normal_queue";
//死信队列名称
private static final String DEAD_QUEUE = "dead_queue";
public static void main(String[] args) throws IOException, TimeoutException {
Channel channel = GetConnection.getChannel();
//声明死信和普通交换机类型 direct
channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
channel.exchangeDeclare(DEAD_EXCHANGE,BuiltinExchangeType.DIRECT);
// 普通队列
Map<String,Object> argument = new HashMap<>();
//过期时间10秒过期 可以不设置，可以交给队列自动去
// argument.put("x-message-ttl",10000);
//正常队列设置死信交换机
argument.put("x-dead-letter-exchange",DEAD_EXCHANGE);
//设置死信RoutingKey
argument.put("x-dead-letter-routing-key","lisi");
//设置正常队列的长度的限制
argument.put("x-max-length",6);
channel.queueDeclare(NORMAL_QUEUE,false,false,false,argument);
///
//声名死信队列
channel.queueDeclare(DEAD_QUEUE,false,false,false,null);
//绑定普通交换机和普通队列
channel.queueBind(NORMAL_QUEUE,NORMAL_EXCHANGE,"zhangsan");
//绑定死信的交换机与死信队列
channel.queueBind(DEAD_QUEUE,DEAD_EXCHANGE,"lisi");
System.out.println("等待接受......");
//绑定死信的交换机和死信的对列
DeliverCallback deliverCallback = (consumer,message)->{
System.out.println("Consumer 01接受到消息是：" + new String(message.getBody(),"UTF-8"));
};
channel.basicConsume(NORMAL_QUEUE,true,deliverCallback,consumer->{});
}
}
public class Product {
//普通交换机的名称
public static final String NORMAL_EXCHANGE = "normal_exchange";
public static void main(String[] args) throws IOException, TimeoutException {
Channel channel = GetConnection.getChannel();
//死信消息，设置TTL时间 单位是ms
// AMQP.BasicProperties properties =
// new AMQP.BasicProperties()
//.builder().expiration("10000").build();
for (int i = 0; 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);
}
}
}
消息被拒绝
一旦消费者拒绝接受，就会成为死信队列。
public class Product {
//普通交换机的名称
public static final String NORMAL_EXCHANGE = "normal_exchange";
public static void main(String[] args) throws IOException, TimeoutException {
Channel channel = GetConnection.getChannel();
//死信消息，设置TTL时间 单位是ms
//演示长度 AMQP.BasicProperties properties =
// new AMQP.BasicProperties()
// .builder().expiration("10000").build();
for (int i = 0; i < 11; i++) {
String message = "info "+ i; //properties
channel.basicPublish(NORMAL_EXCHANGE,"zhangsan",null,message.getBytes());
System.out.println("生产者发送消息:"+message);
}
}
}
public class Consumer01 {
//普通交换机的名称
private static final String NORMAL_EXCHANGE = "normal_exchange";
//死信交换机的名称
private static final String DEAD_EXCHANGE = "dead_exchange";
//普通队列名称
private static final String NORMAL_QUEUE = "normal_queue";
//死信队列名称
private static final String DEAD_QUEUE = "dead_queue";
public static void main(String[] args) throws IOException, TimeoutException {
Channel channel = GetConnection.getChannel();
//声明死信和普通交换机类型 direct
channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
channel.exchangeDeclare(DEAD_EXCHANGE,BuiltinExchangeType.DIRECT);
// 普通队列
Map<String,Object> argument = new HashMap<>();
//过期时间10秒过期 可以不设置，可以交给队列自动去
// argument.put("x-message-ttl",10000);
//正常队列设置死信交换机
argument.put("x-dead-letter-exchange",DEAD_EXCHANGE);
//设置死信RoutingKey
argument.put("x-dead-letter-routing-key","lisi");
//设置正常队列的长度的限制
//演示拒绝 argument.put("x-max-length",6);
channel.queueDeclare(NORMAL_QUEUE,false,false,false,argument);
///
//声名死信队列
channel.queueDeclare(DEAD_QUEUE,false,false,false,null);
//绑定普通交换机和普通队列
channel.queueBind(NORMAL_QUEUE,NORMAL_EXCHANGE,"zhangsan");
//绑定死信的交换机与死信队列
channel.queueBind(DEAD_QUEUE,DEAD_EXCHANGE,"lisi");
System.out.println("等待接受......");
//绑定死信的交换机和死信的对列
DeliverCallback deliverCallback = (consumer,message)->{
//拒绝消息在这里写
String message1 = new String(message.getBody(),"UTF-8");
//指定你要拒绝的消息
if(message1.equals("info 5")){
System.out.println("此消息是被拒绝的"+ message1);
//拒接接收，且不放回队列，避免队列重新发送
channel.basicReject(message.getEnvelope().getDeliveryTag(),false);
}else {
System.out.println("Consumer 01接受到消息是：" + new String(message.getBody(),"UTF-8"));
// 接收且不放回
channel.basicAck(message.getEnvelope().getDeliveryTag(),false);
}
};
//开启手动应答, //true是自动应答。
channel.basicConsume(NORMAL_QUEUE,false,deliverCallback,consumer->{});
}
}
public class Consumer02 {
private static final String DEAD_EXCHANGE = "dead_exchange";
//死信队列名称
private static final String DEAD_QUEUE = "dead_queue";
public static void main(String[] args) throws IOException, TimeoutException {
Channel channel = GetConnection.getChannel();
channel.queueBind(DEAD_QUEUE,DEAD_EXCHANGE,"lisi");
System.out.println("等待接受......");
//绑定死信的交换机和死信的对列
DeliverCallback deliverCallback = (consumer,message)->{
System.out.println("Consumer 02接受到消息是：" + new String(message.getBody(),"UTF-8"));
};
channel.basicConsume(DEAD_QUEUE,true,deliverCallback,consumer->{});
}
}
