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。
//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();
//声明死信和普通交换机 类型为direct
channel.exchangeDeclare(NORMAL_EXCHANGE, BuiltinExchangeType.DIRECT);
channel.exchangeDeclare(DEAD_EXCHANGE,BuiltinExchangeType.DIRECT);
//声明普通队列
Map<String,Object> arguments = new HashMap<>();
//过期时间
//arguments.put("X-message-ttl",100000);
//正常队列设置死信交换机
arguments.put("x-dead-letter-exchange",DEAD_EXCHANGE);
//设置死信RountingKey
arguments.put("x-dead-letter-routing-key","lisi");
channel.queueDeclare(NORMAL_QUEUE,false,false,false, arguments);
/
//声明死信队列
channel.queueDeclare(DEAD_QUEUE,false,false,false,null);
//绑定普通的交换机和队列
channel.queueBind(NORMAL_QUEUE,NORMAL_EXCHANGE,"zhangsan");
//绑定死信的交换机和死信的队列
channel.queueBind(DEAD_QUEUE,DEAD_EXCHANGE,"lisi");
System.out.println("等待接受消息......");
//接受消息
DeliverCallback deliverCallback = (consumerTag, message)->{
System.out.println("Consumer01接收到的消息:" +
new String(message.getBody(), StandardCharsets.UTF_8));
};
//消费者取消消息时回调接口
channel.basicConsume(NORMAL_QUEUE,true,deliverCallback,consumerTag -> {});
}
}
public class Producer {
//普通交换机的名称
public static final String NORMAL_EXCHANGE = "normal_exchange";
public static void main(String[] args) throws Exception {
Channel channel = RabbitMqUtils.getChannel();
//死信消息 设置TTL时间 time to live
AMQP.BasicProperties properties =
new AMQP.BasicProperties()
.builder().expiration("10000")
.build();
for (int i = 0; i < 10; i++) {
String message = "info" + i;
channel.basicPublish(NORMAL_EXCHANGE,"zhangsan",properties,message.getBytes(StandardCharsets.UTF_8));
}
}
}
//以上步骤完成后开启
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("等待接受消息......");
//接受消息
DeliverCallback deliverCallback = (consumerTag, message)->{
System.out.println("Consumer02接收到的消息:" +
new String(message.getBody(), StandardCharsets.UTF_8));
};
//消费者取消消息时回调接口
channel.basicConsume(DEAD_QUEUE,true,deliverCallback,consumerTag -> {});
}
}
1、消息生产者代码去掉 TTL 属性
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)
//设置正常队列的长度的限制
arguments.put("x-max-length",6);
注意此时需要把原先队列删除,因为参数改变了。
1、消息生产者代码同上生产者一致
2、C1 消费者修改以下代码(此次不需要关闭)
//接受消息
DeliverCallback deliverCallback = (consumerTag, message)->{
String msg = new String(message.getBody(),StandardCharsets.UTF_8);
if (msg.equals("info5")){
System.out.println(msg + "此消息是被C1拒绝的");
channel.basicReject(message.getEnvelope().getDeliveryTag(),false);
}else {
System.out.println("Consumer01接收到的消息:" + msg);
channel.basicAck(message.getEnvelope().getDeliveryTag(),false);
}
};
//消费者取消消息时回调接口
//开启手动应答
channel.basicConsume(NORMAL_QUEUE,false,deliverCallback,consumerTag -> {});
延时队列,队列内部是有序的,最重要的特性就体现在它的延时属性上,延时队列中的元素是希望在指定时间到了以后或之前取出和处理,简单来说,延时队列就是用来存放需要在指定时间被处理的元素的队列。
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-amqpartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-webartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-testartifactId>
<scope>testscope>
dependency>
<dependency>
<groupId>com.alibabagroupId>
<artifactId>fastjsonartifactId>
<version>1.2.47version>
dependency>
<dependency>
<groupId>org.projectlombokgroupId>
<artifactId>lombokartifactId>
dependency>
<dependency>
<groupId>io.springfoxgroupId>
<artifactId>springfox-swagger2artifactId>
<version>2.9.2version>
dependency>
<dependency>
<groupId>io.springfoxgroupId>
<artifactId>springfox-swagger-uiartifactId>
<version>2.9.2version>
dependency>
<dependency>
<groupId>org.springframework.amqpgroupId>
<artifactId>spring-rabbit-testartifactId>
<scope>testscope>
dependency>
spring.rabbitmq.host=192.168.196.132
spring.rabbitmq.port=5672
spring.rabbitmq.username=admin
spring.rabbitmq.password=123
@Configuration
@EnableSwagger2
public class SwaggerConfig {
@Bean
public Docket webApiConfig() {
return new Docket(DocumentationType.SWAGGER_2)
.groupName("webApi")
.apiInfo(webApiInfo())
.select()
.build();
}
private ApiInfo webApiInfo() {
return new ApiInfoBuilder()
.title("rabbitmq 接口文档")
.description("本文档描述了 rabbitmq 微服务接口定义")
.version("1.0")
.contact(new Contact("enjoy6288", "http://atguigu.com",
"1551388580@qq.com")).build();
}
}
创建两个队列 QA 和 QB,两者队列 TTL 分别设置为 10S 和 40S,然后在创建一个交换机 X 和死信交换机 Y,它们的类型都是 direct,创建一个死信队列 QD,它们的绑定关系如下:
@Configuration
public class TtlQueueConfig {
//普通交换机的名称
public static final String X_EXCHANGE = "X";
//死信交换机的名称
public static final String Y_DEAD_LETTER_EXCHANGE = "Y";
//普通队列的名称
public static final String QUEUE_A = "QA";
public static final String QUEUE_B = "QB";
//死信队列的名称
public static final String DEAD_LETTER_QUEUE = "QD";
//声明x交换机
@Bean("xExchange")
public DirectExchange xExchange(){
return new DirectExchange(X_EXCHANGE);
}
//声明y交换机
@Bean("yExchange")
public DirectExchange yExchange(){
return new DirectExchange(Y_DEAD_LETTER_EXCHANGE);
}
//声明普通队列 TTL 10s
@Bean("queueA")
public Queue queueA(){
Map<String,Object> arguments = new HashMap<>();
//设置死信交换机
arguments.put("x-dead-letter-exchange",Y_DEAD_LETTER_EXCHANGE);
//设置死信RountingKey
arguments.put("x-dead-letter-routing-key","YD");
//设置TTL
arguments.put("x-message-ttl",10000);
return QueueBuilder.durable(QUEUE_A).withArguments(arguments).build();
}
//声明普通队列 TTL 40s
@Bean("queueB")
public Queue queueB(){
Map<String,Object> arguments = new HashMap<>();
//设置死信交换机
arguments.put("x-dead-letter-exchange",Y_DEAD_LETTER_EXCHANGE);
//设置死信RountingKey
arguments.put("x-dead-letter-routing-key","YD");
//设置TTL
arguments.put("x-message-ttl",40000);
return QueueBuilder.durable(QUEUE_B).withArguments(arguments).build();
}
//死信队列
@Bean("queueD")
public Queue queueD(){
return QueueBuilder.durable(DEAD_LETTER_QUEUE).build();
}
//绑定
@Bean
public Binding queueABindingX(@Qualifier("queueA") Queue queueA,
@Qualifier("xExchange") DirectExchange xExchange){
return BindingBuilder.bind(queueA).to(xExchange).with("XA");
}
@Bean
public Binding queueBBindingX(@Qualifier("queueB") Queue queueB,
@Qualifier("xExchange") DirectExchange xExchange){
return BindingBuilder.bind(queueB).to(xExchange).with("XB");
}
@Bean
public Binding queueBBindingy(@Qualifier("queueD") Queue queueD,
@Qualifier("yExchange") DirectExchange yExchange){
return BindingBuilder.bind(queueD).to(yExchange).with("YD");
}
}
@Slf4j
@RestController
@RequestMapping("/ttl")
public class SendMsgController {
@Autowired
private RabbitTemplate rabbitTemplate;
//开始发消息
@GetMapping("/sendMsg/{message}")
public void sendMsg(@PathVariable String message){
log.info("当前时间:{},发送一条信息给两个TTL队列:{}",new Date().toString(),message);
rabbitTemplate.convertAndSend("X","XA","消息来自TTL为10s的队列:" + message);
rabbitTemplate.convertAndSend("X","XB","消息来自TTL为40s的队列:" + message);
}
}
@Slf4j
@Component
public class DeadLetterQueueConsumer {
//接受消息
@RabbitListener(queues = "QD")
public void receiveD(Message message, Channel channel){
String msg = new String(message.getBody());
log.info("当前时间:{},收到死信队列的消息:{}",new Date().toString(),msg);
}
}
当前时间:Thu Apr 28 17:04:34 CST 2022,发送一条信息给两个TTL队列:嘻嘻嘻
当前时间:Thu Apr 28 17:04:43 CST 2022,收到死信队列的消息:消息来自TTL为10s的队列:嘻嘻嘻
当前时间:Thu Apr 28 17:05:11 CST 2022,收到死信队列的消息:消息来自TTL为40s的队列:嘻嘻嘻
第一条消息在 10S 后变成了死信消息,然后被消费者消费掉,第二条消息在 40S 之后变成了死信消息,然后被消费掉,这样一个延时队列就打造完成了。
不过,如果这样使用的话,岂不是每增加一个新的时间需求,就要新增一个队列,这里只有 10S 和 40S 两个时间选项,如果需要一个小时后处理,那么就需要增加 TTL 为一个小时的队列,如果是预定会议室然后提前通知这样的场景,岂不是要增加无数个队列才能满足需求?
只需要在上面的配置类中新增一个普通队列QC:
//普通队列名称
public static final String QUEUE_C = "QC";
//声明QC
@Bean("queueC")
public Queue queueC(){
Map<String,Object> arguments = new HashMap<>();
//设置死信交换机
arguments.put("x-dead-letter-exchange",Y_DEAD_LETTER_EXCHANGE);
//设置死信RountingKey
arguments.put("x-dead-letter-routing-key","YD");
return QueueBuilder.durable().withArguments(arguments).build();
}
@Bean
public Binding queueCBindingX(@Qualifier("queueC") Queue queueC,
@Qualifier("xExchange") DirectExchange xExchange){
return BindingBuilder.bind(queueC).to(xExchange).with("XC");
}
生产者中设置ttl:
//开始发消息 消息+TTL
@GetMapping("/sendExpirationMsg/{message}/{ttlTime}")
public void sendMsg(@PathVariable String message,
@PathVariable String ttlTime){
log.info("当前时间:{},发送一条时长 {} 毫秒TTL信息给队列QC:{}",
new Date().toString(),ttlTime,message);
rabbitTemplate.convertAndSend("X","XC",message,(msg -> {
//发送消息的时候设置延迟时长
msg.getMessageProperties().setExpiration(ttlTime);
return msg;
}));
}
发送请求:
http://localhost:8080/ttl/sendExpirationMsg/你好 1/20000
http://localhost:8080/ttl/sendExpirationMsg/你好 2/2000
当前时间:Thu Apr 28 20:26:36 CST 2022,发送一条时长 20000 毫秒TTL信息给队列QC:你好 1
当前时间:Thu Apr 28 20:26:47 CST 2022,发送一条时长 2000 毫秒TTL信息给队列QC:你好 2
当前时间:Thu Apr 28 20:26:54 CST 2022,收到死信队列的消息:你好 1
当前时间:Thu Apr 28 20:26:54 CST 2022,收到死信队列的消息:你好 2
看起来似乎没什么问题,但是在最开始的时候,就介绍过如果使用在消息属性上设置 TTL 的方式,消息可能并不会按时“死亡“,因为 RabbitMQ 只会检查第一个消息是否过期,如果过期则丢到死信队列,如果第一个消息的延时时长很长,而第二个消息的延时时长很短,第二个消息并不会优先得到执行。
在官网上下载 https://www.rabbitmq.com/community-plugins.html,下载rabbitmq_delayed_message_exchange 插件,然后解压放置到 RabbitMQ 的插件目录。
cp rabbitmq_delayed_message_exchange-3.9.0.ez /usr/lib/rabbitmq/lib/rabbitmq_server-3.9.15/plugins/
rabbitmq-plugins enable rabbitmq_delayed_message_exchange
systemctl restart rabbitmq-server
@Configuration
public class DelayedQueueConfig {
//交换机
public static final String DELAYED_QUEUE_NAME = "delayed.queue";
//队列
public static final String DELAYED_EXCHANGE_NAME = "delayed.exchange";
//routingKey
public static final String DELAYED_ROUTING_KEY = "delayed.routingkey";
//声明交换机
@Bean
public CustomExchange delayedExchange() {
Map<String, Object> args = new HashMap<>();
//自定义交换机的类型
args.put("x-delayed-type", "direct");
return new CustomExchange(DELAYED_EXCHANGE_NAME,
"x-delayed-message", true, false, args);
}
//声明队列
@Bean
public Queue delayedQueue() {
return new Queue(DELAYED_QUEUE_NAME);
}
//绑定
@Bean
public Binding bindingDelayedQueue(@Qualifier("delayedQueue") Queue queue,
@Qualifier("delayedExchange") CustomExchange
delayedExchange) {
return BindingBuilder.bind(queue).to(delayedExchange).with(DELAYED_ROUTING_KEY).noargs();
}
}
//基于插件开始发消息 消息+TTL
@GetMapping("/sendDelayMsg/{message}/{delayTime}")
public void sendMsg(@PathVariable String message,
@PathVariable Integer delayTime){
log.info("当前时间:{},发送一条时长 {} 毫秒信息给延迟队列delayed.queue:{}",
new Date().toString(),delayTime,message);
rabbitTemplate.convertAndSend(DelayedQueueConfig.DELAYED_EXCHANGE_NAME,DelayedQueueConfig.DELAYED_ROUTING_KEY,message,(msg -> {
//发送消息的时候设置延迟时长
msg.getMessageProperties().setDelay(delayTime);
return msg;
}));
}
@Slf4j
@Component
public class DelayQueueConsumer {
//监听消息
@RabbitListener(queues = DelayedQueueConfig.DELAYED_QUEUE_NAME)
public void receiveDelayQueue(Message message){
String msg = new String(message.getBody());
log.info("当前时间:{},收到延迟队列的消息:{}",new Date().toString(),msg);
}
}
发送请求:
http://localhost:8080/ttl/sendDelayMsg/come on baby1/20000
http://localhost:8080/ttl/sendDelayMsg/come on baby2/2000
当前时间:Thu Apr 28 21:02:47 CST 2022,发送一条时长 20000 毫秒信息给延迟队列delayed.queue:come on baby1
当前时间:Thu Apr 28 21:02:54 CST 2022,发送一条时长 2000 毫秒信息给延迟队列delayed.queue:come on baby2
当前时间:Thu Apr 28 21:02:56 CST 2022,收到延迟队列的消息:come on baby2
当前时间:Thu Apr 28 21:03:05 CST 2022,收到延迟队列的消息:come on baby1
第二个消息被先消费掉了,符合预期。