Annotation Type EnableRabbit


  • @Target(TYPE)
    @Retention(RUNTIME)
    @Documented
    @Import(RabbitListenerConfigurationSelector.class)
    public @interface EnableRabbit
    Enable Rabbit listener annotated endpoints that are created under the cover by a RabbitListenerContainerFactory. To be used on Configuration classes as follows:
     @Configuration
     @EnableRabbit
     public class AppConfig {
         @Bean
         public SimpleRabbitListenerContainerFactory myRabbitListenerContainerFactory() {
           SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
           factory.setConnectionFactory(connectionFactory());
           factory.setMaxConcurrentConsumers(5);
           return factory;
         }
         // other @Bean definitions
     }
    The RabbitListenerContainerFactory is responsible to create the listener container responsible for a particular endpoint. Typical implementations, as the SimpleRabbitListenerContainerFactory used in the sample above, provides the necessary configuration options that are supported by the underlying MessageListenerContainer.

    @EnableRabbit enables detection of RabbitListener annotations on any Spring-managed bean in the container. For example, given a class MyService:

     package com.acme.foo;
    
     public class MyService {
         @RabbitListener(containerFactory="myRabbitListenerContainerFactory", queues="myQueue")
         public void process(String msg) {
             // process incoming message
         }
     }
    The container factory to use is identified by the containerFactory attribute defining the name of the RabbitListenerContainerFactory bean to use. When none is set a RabbitListenerContainerFactory bean with name rabbitListenerContainerFactory is assumed to be present.

    the following configuration would ensure that every time a Message is received on the Queue named "myQueue", MyService.process() is called with the content of the message:

     @Configuration
     @EnableRabbit
     public class AppConfig {
         @Bean
         public MyService myService() {
             return new MyService();
         }
    
         // Rabbit infrastructure setup
     }
    Alternatively, if MyService were annotated with @Component, the following configuration would ensure that its @RabbitListener annotated method is invoked with a matching incoming message:
     @Configuration
     @EnableRabbit
     @ComponentScan(basePackages="com.acme.foo")
     public class AppConfig {
     }
    Note that the created containers are not registered against the application context but can be easily located for management purposes using the RabbitListenerEndpointRegistry.

    Annotated methods can use flexible signature; in particular, it is possible to use the Message abstraction and related annotations, see RabbitListener Javadoc for more details. For instance, the following would inject the content of the message and a a custom "myCounter" AMQP header:

     @RabbitListener(containerFactory = "myRabbitListenerContainerFactory", queues = "myQueue")
     public void process(String msg, @Header("myCounter") int counter) {
         // process incoming message
     }
    These features are abstracted by the MessageHandlerMethodFactory that is responsible to build the necessary invoker to process the annotated method. By default, DefaultMessageHandlerMethodFactory is used.

    When more control is desired, a @Configuration class may implement RabbitListenerConfigurer. This allows access to the underlying RabbitListenerEndpointRegistrar instance. The following example demonstrates how to specify an explicit default RabbitListenerContainerFactory

     @Configuration
     @EnableRabbit
     public class AppConfig implements RabbitListenerConfigurer {
         @Override
         public void configureRabbitListeners(RabbitListenerEndpointRegistrar registrar) {
             registrar.setContainerFactory(myRabbitListenerContainerFactory());
         }
    
         @Bean
         public RabbitListenerContainerFactory<?> myRabbitListenerContainerFactory() {
             // factory settings
         }
    
         @Bean
         public MyService myService() {
             return new MyService();
         }
     }
     
    For reference, the example above can be compared to the following Spring XML configuration:
     <beans>
         <rabbit:annotation-driven container-factory="myRabbitListenerContainerFactory"/>
    
         <bean id="myRabbitListenerContainerFactory"
               class="org.springframework.amqp.rabbit.config.SimpleRabbitListenerContainerFactory">
               // factory settings
         </bean>
    
         <bean id="myService" class="com.acme.foo.MyService"/>
     </beans>
     
    It is also possible to specify a custom RabbitListenerEndpointRegistry in case you need more control on the way the containers are created and managed. The example below also demonstrates how to customize the RabbitHandlerMethodFactory to use with a custom Validator so that payloads annotated with Validated are first validated against a custom Validator.
     @Configuration
     @EnableRabbit
     public class AppConfig implements RabbitListenerConfigurer {
         @Override
         public void configureRabbitListeners(RabbitListenerEndpointRegistrar registrar) {
             registrar.setEndpointRegistry(myRabbitListenerEndpointRegistry());
             registrar.setMessageHandlerMethodFactory(myMessageHandlerMethodFactory());
         }
    
         @Bean
         public RabbitListenerEndpointRegistry<?> myRabbitListenerEndpointRegistry() {
             // registry configuration
         }
    
         @Bean
         public RabbitHandlerMethodFactory myMessageHandlerMethodFactory() {
            DefaultRabbitHandlerMethodFactory factory = new DefaultRabbitHandlerMethodFactory();
            factory.setValidator(new MyValidator());
            return factory;
         }
    
         @Bean
         public MyService myService() {
             return new MyService();
         }
     }
     
    For reference, the example above can be compared to the following Spring XML configuration:
     <beans>
         <rabbit:annotation-driven registry="myRabbitListenerEndpointRegistry"
             handler-method-factory="myRabbitHandlerMethodFactory"/>
    
         <bean id="myRabbitListenerEndpointRegistry"
               class="org.springframework.amqp.rabbit.config.RabbitListenerEndpointRegistry">
               // registry configuration
         </bean>
    
         <bean id="myRabbitHandlerMethodFactory"
               class="org.springframework.amqp.rabbit.config.DefaultRabbitHandlerMethodFactory">
             <property name="validator" ref="myValidator"/>
         </bean>
    
         <bean id="myService" class="com.acme.foo.MyService"/>
     </beans>
     
    Implementing RabbitListenerConfigurer also allows for fine-grained control over endpoints registration via the RabbitListenerEndpointRegistrar. For example, the following configures an extra endpoint:
     @Configuration
     @EnableRabbit
     public class AppConfig implements RabbitListenerConfigurer {
         @Override
         public void configureRabbitListeners(RabbitListenerEndpointRegistrar registrar) {
             SimpleRabbitListenerEndpoint myEndpoint = new SimpleRabbitListenerEndpoint();
             // ... configure the endpoint
             registrar.registerEndpoint(endpoint, anotherRabbitListenerContainerFactory());
         }
    
         @Bean
         public MyService myService() {
             return new MyService();
         }
    
         @Bean
         public RabbitListenerContainerFactory<?> anotherRabbitListenerContainerFactory() {
             // ...
         }
    
         // Rabbit infrastructure setup
     }
     
    Note that all beans implementing RabbitListenerConfigurer will be detected and invoked in a similar fashion. The example above can be translated in a regular bean definition registered in the context in case you use the XML configuration.
    Since:
    1.4
    Author:
    Stephane Nicoll, Artem Bilan
    See Also:
    RabbitListener, RabbitListenerAnnotationBeanPostProcessor, RabbitListenerEndpointRegistrar, RabbitListenerEndpointRegistry