RabbitMQ(五):主题(Topics)

前言

先决条件
✔️ 正确安装 RabbitMQ 并将其运行在 localhost:5672 上
✔️ 已经了解了 RabbitMQ 中的一些基础概念

上一个教程中,我们改进了我们的日志系统。我们使用 direct exchange 替代了 fanout exchange,从只能盲目的广播消息改进为有可能选择性的接收日志。

尽管 direct exchange 能够改善我们的系统,但是它也有它的限制——没办法基于多个标准执行路由操作。

在我们的日志系统中,我们不只希望订阅基于严重程度的日志,同时还希望订阅基于发送来源的日志。Unix 工具 syslog 就是同时基于严重程度 -severity (info/warn/crit…) 和 设备 -facility (auth/cron/kern…) 来路由日志的。

如果这样的话,将会给予我们非常大的灵活性,我们既可以监听来源于”cron”的严重程度为”critical errors”的日志,也可以监听来源于”kern”的所有日志。

为了实现这个目的,接下来我们学习如何使用另一种更复杂的交换器——topic exchange。

Topic exchange

topic exchange 与 direct exchange 类似,也是将消息路由到 binding key 与 routing key 相匹配的 Queue 中,但这里的匹配规则有些不同,它约定:

  • routing key 为一个句点号.分隔的字符串(我们将被句点号.分隔开的每一段独立的字符串称为一个单词),如 “stock.usd.nyse”、”nyse.vmw”、”quick.orange.rabbit”
  • binding key 与 routing key 一样也是句点号.分隔的字符串
  • binding key 中可以存在两种特殊字符*#,用于做模糊匹配,其中*用于匹配一个单词,#用于匹配多个单词(可以是零个)

这个例子里,我们发送的所有消息都是用来描述小动物的。发送的消息所携带的路由键是由三个单词所组成的,这三个单词被两个.分割开。路由键里的第一个单词描述的是动物的速度,第二个单词是动物的颜色,第三个是动物的种类。所以它看起来是这样的:”速度.颜色.种类”。

我们创建了三个绑定:Q1 的 binding key 为”.orange.“,Q2 的 binding key 为”..rabbit”和”lazy.#”。

这三个 binding key 被可以总结为:

  • Q1 对所有的桔黄色动物都感兴趣。
  • Q2 则是对所有的兔子和所有懒惰的动物感兴趣。

以上图中的配置为例:
routingKey=”quick.orange.rabbit” 的消息会同时路由到 Q1 与 Q2
routingKey=”lazy.orange.fox” 的消息会路由到 Q1 与 Q2
routingKey=”lazy.brown.fox” 的消息会路由到 Q2
routingKey=”lazy.pink.rabbit” 的消息会路由到 Q2(只会投递给 Q2 一次,虽然这个 routingKey 与 Q2 的两个 bindingKey 都匹配)
routingKey=”quick.brown.fox”、routingKey=”orange”、routingKey=”quick.orange.male.rabbit” 的消息将会被丢弃,因为它们没有匹配任何 bindingKey

如果我们违反约定,发送了一个 routing key 为一个单词或者四个单词(”orange” or “quick.orange.male.rabbit”)的消息时,该消息不会投递给任何一个队列,而且会丢失掉。

但是,即使”lazy.orange.male.rabbit”有四个单词,他还是会匹配最后一个绑定,并且被投递到第二个队列中。

topic exchange
topic exchange 是强大的,它可以表现出跟其他 exchange 类似的行为。
当一个队列的 binding key 为 “#”(井号) 的时候,它会接收所有消息,而不考虑 routing key,就像 fanout exchange。
当 * (星号) 和 # (井号) 这两个特殊字符都未在绑定键中出现的时候,此时 topic exchange 会表现得像 direct exchange 一样。

代码整合

生产者

public class Tut5Sender {

    @Autowired
    private AmqpTemplate template;

    @Autowired
    private TopicExchange topic;

    private int index;

    private int count;

    private final String[] keys = {"quick.orange.rabbit",
            "lazy.orange.elephant", "quick.orange.fox",
            "lazy.brown.fox", "lazy.pink.rabbit", "quick.brown.fox"};


    @Scheduled(fixedDelay = 1000, initialDelay = 500)
    public void send() {
        StringBuilder builder = new StringBuilder("Hello to ");
        if (++this.index == keys.length) {
            this.index = 0;
        }
        String key = keys[this.index];
        builder.append(key).append(' ');
        builder.append(Integer.toString(++this.count));
        String message = builder.toString();
        template.convertAndSend(topic.getName(), key, message);
        System.out.println(" [x] Sent '" + message + "'");
    }

}

消费者

public class Tut5Receiver {

    @RabbitListener(queues = "#{autoDeleteQueue1}")
    public void receiver1(String in) throws InterruptedException {
        receive(in, 1);
    }

    @RabbitListener(queues = "#{autoDeleteQueue2}")
    public void receiver2(String in) throws InterruptedException {
        receive(in, 2);
    }

    private void receive(String in, int instance) throws InterruptedException {
        StopWatch watch = new StopWatch();
        watch.start();
        System.out.println("instance " + instance + " [x] Received '" + in + "'");
        doWork(in);
        watch.stop();
        System.out.println("instance " + instance + " [x] Done in "
                + watch.getTotalTimeSeconds() + "s");
    }

    private void doWork(String in) throws InterruptedException {
        for (char c : in.toCharArray()) {
            if (c == '.') {
                Thread.sleep(1000);
            }
        }
    }

}

配置类

@Profile({"tut5", "topics"})
@Configuration
public class Tut5Config {

    @Bean
    public TopicExchange topic() {
        return new TopicExchange("tut.topic");
    }

    @Profile("receiver")
    private static class ReceiverConfig {

        @Bean
        public Queue autoDeleteQueue1() {
            return new AnonymousQueue();
        }

        @Bean
        public Queue autoDeleteQueue2() {
            return new AnonymousQueue();
        }

        @Bean
        public Binding binding1a(TopicExchange topic, Queue autoDeleteQueue1) {
            return BindingBuilder.bind(autoDeleteQueue1)
                    .to(topic)
                    .with("*.orange.*");
        }

        @Bean
        public Binding binding2a(TopicExchange topic, Queue autoDeleteQueue2) {
            return BindingBuilder.bind(autoDeleteQueue2)
                    .to(topic)
                    .with("*.*.rabbit");
        }

        @Bean
        public Binding binding2b(TopicExchange topic, Queue autoDeleteQueue2) {
            return BindingBuilder.bind(autoDeleteQueue2)
                    .to(topic)
                    .with("lazy.#");
        }

        @Bean
        public Tut5Receiver receiver() {
            return new Tut5Receiver();
        }

    }

    @Profile("sender")
    @Bean
    public Tut5Sender sender() {
        return new Tut5Sender();
    }

}

运行

maven 编译

mvn clean package -Dmaven.test.skip=true

运行

java -jar target/rabbitmq-tutorial-0.0.1-SNAPSHOT.jar --spring.profiles.active=tut5,receiver  --tutorial.client.duration=60000
java -jar target/rabbitmq-tutorial-0.0.1-SNAPSHOT.jar --spring.profiles.active=tut5,sender  --tutorial.client.duration=60000

输出

// Sender
Ready ... running for 60000ms
 [x] Sent 'Hello to lazy.orange.elephant 1'
 [x] Sent 'Hello to quick.orange.fox 2'
 [x] Sent 'Hello to lazy.brown.fox 3'
 [x] Sent 'Hello to lazy.pink.rabbit 4'
 [x] Sent 'Hello to quick.brown.fox 5'
 [x] Sent 'Hello to quick.orange.rabbit 6'
 [x] Sent 'Hello to lazy.orange.elephant 7'
 [x] Sent 'Hello to quick.orange.fox 8'
 [x] Sent 'Hello to lazy.brown.fox 9'
 [x] Sent 'Hello to lazy.pink.rabbit 10'

// Receiver
Ready ... running for 60000ms
instance 1 [x] Received 'Hello to lazy.orange.elephant 1'
instance 2 [x] Received 'Hello to lazy.orange.elephant 1'
instance 2 [x] Done in 2.004s
instance 1 [x] Done in 2.004s
instance 2 [x] Received 'Hello to lazy.brown.fox 3'
instance 1 [x] Received 'Hello to quick.orange.fox 2'
instance 1 [x] Done in 2.006s
instance 2 [x] Done in 2.006s
instance 2 [x] Received 'Hello to lazy.pink.rabbit 4'
instance 1 [x] Received 'Hello to quick.orange.rabbit 6'
instance 2 [x] Done in 2.006s
instance 2 [x] Received 'Hello to quick.orange.rabbit 6'
instance 1 [x] Done in 2.007s
instance 1 [x] Received 'Hello to lazy.orange.elephant 7'
instance 2 [x] Done in 2.006s
instance 2 [x] Received 'Hello to lazy.orange.elephant 7'
instance 1 [x] Done in 2.003s
instance 1 [x] Received 'Hello to quick.orange.fox 8'
instance 2 [x] Done in 2.005s
instance 2 [x] Received 'Hello to lazy.brown.fox 9'
instance 1 [x] Done in 2.005s
instance 2 [x] Done in 2.004s
instance 2 [x] Received 'Hello to lazy.pink.rabbit 10'

代码地址:https://github.com/zhaoyibo/rabbitmq-tutorial
相关文章:

  1. RabbitMQ(零):基础概念
  2. RabbitMQ(一):Hello World
  3. RabbitMQ(二):工作队列(Work queues)
  4. RabbitMQ(三):发布订阅(Publish/Subscribe)
  5. RabbitMQ(四):路由(Routing)
  6. RabbitMQ(五):主题(Topics)
  7. RabbitMQ(六):远程过程调用(RPC)

参考

RabbitMQ Tutorial Five