多個 Broker (或叢集) 支援

在 2.3 版本中，為單一應用程式與多個 Broker 或 Broker 叢集之間進行通訊新增了更多便利性。在消費者端，主要的好處是基礎架構可以自動將自動宣告的佇列與適當的 Broker 建立關聯。

以下範例最能說明這一點

@SpringBootApplication(exclude = RabbitAutoConfiguration.class)
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Bean
    CachingConnectionFactory cf1() {
        return new CachingConnectionFactory("localhost");
    }

    @Bean
    CachingConnectionFactory cf2() {
        return new CachingConnectionFactory("otherHost");
    }

    @Bean
    CachingConnectionFactory cf3() {
        return new CachingConnectionFactory("thirdHost");
    }

    @Bean
    SimpleRoutingConnectionFactory rcf(CachingConnectionFactory cf1,
            CachingConnectionFactory cf2, CachingConnectionFactory cf3) {

        SimpleRoutingConnectionFactory rcf = new SimpleRoutingConnectionFactory();
        rcf.setDefaultTargetConnectionFactory(cf1);
        rcf.setTargetConnectionFactories(Map.of("one", cf1, "two", cf2, "three", cf3));
        return rcf;
    }

    @Bean("factory1-admin")
    RabbitAdmin admin1(CachingConnectionFactory cf1) {
        return new RabbitAdmin(cf1);
    }

    @Bean("factory2-admin")
    RabbitAdmin admin2(CachingConnectionFactory cf2) {
        return new RabbitAdmin(cf2);
    }

    @Bean("factory3-admin")
    RabbitAdmin admin3(CachingConnectionFactory cf3) {
        return new RabbitAdmin(cf3);
    }

    @Bean
    public RabbitListenerEndpointRegistry rabbitListenerEndpointRegistry() {
        return new RabbitListenerEndpointRegistry();
    }

    @Bean
    public RabbitListenerAnnotationBeanPostProcessor postProcessor(RabbitListenerEndpointRegistry registry) {
        MultiRabbitListenerAnnotationBeanPostProcessor postProcessor
                = new MultiRabbitListenerAnnotationBeanPostProcessor();
        postProcessor.setEndpointRegistry(registry);
        postProcessor.setContainerFactoryBeanName("defaultContainerFactory");
        return postProcessor;
    }

    @Bean
    public SimpleRabbitListenerContainerFactory factory1(CachingConnectionFactory cf1) {
        SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
        factory.setConnectionFactory(cf1);
        return factory;
    }

    @Bean
    public SimpleRabbitListenerContainerFactory factory2(CachingConnectionFactory cf2) {
        SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
        factory.setConnectionFactory(cf2);
        return factory;
    }

    @Bean
    public SimpleRabbitListenerContainerFactory factory3(CachingConnectionFactory cf3) {
        SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
        factory.setConnectionFactory(cf3);
        return factory;
    }

    @Bean
    RabbitTemplate template(SimpleRoutingConnectionFactory rcf) {
        return new RabbitTemplate(rcf);
    }

    @Bean
    ConnectionFactoryContextWrapper wrapper(SimpleRoutingConnectionFactory rcf) {
        return new ConnectionFactoryContextWrapper(rcf);
    }

}

@Component
class Listeners {

    @RabbitListener(queuesToDeclare = @Queue("q1"), containerFactory = "factory1")
    public void listen1(String in) {

    }

    @RabbitListener(queuesToDeclare = @Queue("q2"), containerFactory = "factory2")
    public void listen2(String in) {

    }

    @RabbitListener(queuesToDeclare = @Queue("q3"), containerFactory = "factory3")
    public void listen3(String in) {

    }

}

如您所見，我們宣告了 3 組基礎架構 (連線工廠、管理員、容器工廠)。如先前討論的，@RabbitListener 可以定義要使用的容器工廠；在此範例中，它們也使用 queuesToDeclare，這會導致佇列在 Broker 上宣告 (如果不存在)。透過使用 <container-factory-name>-admin 慣例命名 RabbitAdmin Bean，基礎架構能夠判斷哪個管理員應該宣告佇列。這也適用於 bindings = @QueueBinding(…)，屆時交換器和繫結也會被宣告。這不適用於 queues，因為它預期佇列已存在。

在生產者端，提供了一個方便的 ConnectionFactoryContextWrapper 類別，使使用 RoutingConnectionFactory (請參閱路由連線工廠) 更加簡單。

如您在上方看到的，已新增一個 SimpleRoutingConnectionFactory Bean，其路由金鑰為 one、two 和 three。還有一個使用該工廠的 RabbitTemplate。以下是使用該範本與包裝器路由到其中一個 Broker 叢集的範例。

@Bean
public ApplicationRunner runner(RabbitTemplate template, ConnectionFactoryContextWrapper wrapper) {
    return args -> {
        wrapper.run("one", () -> template.convertAndSend("q1", "toCluster1"));
        wrapper.run("two", () -> template.convertAndSend("q2", "toCluster2"));
        wrapper.run("three", () -> template.convertAndSend("q3", "toCluster3"));
    };
}