org.springframework.jms.annotation

## Annotation Type EnableJms

    @Target(value=TYPE)
     @Retention(value=RUNTIME)
     @Documented
     @Import(value=JmsBootstrapConfiguration.class)
    public @interface EnableJms

Enable JMS listener annotated endpoints that are created under the cover by a `JmsListenerContainerFactory`. To be used on `Configuration` classes as follows:

     @Configuration
     @EnableJms
     public class AppConfig {

         @Bean
         public DefaultJmsListenerContainerFactory myJmsListenerContainerFactory() {
           DefaultJmsListenerContainerFactory factory = new DefaultJmsListenerContainerFactory();
           factory.setConnectionFactory(connectionFactory());
           factory.setDestinationResolver(destinationResolver());
           factory.setSessionTransacted(true);
           factory.setConcurrency("5");
           return factory;
         }

         // other @Bean definitions
     }

The `JmsListenerContainerFactory` is responsible to create the listener container responsible for a particular endpoint. Typical implementations, as the `DefaultJmsListenerContainerFactory` used in the sample above, provides the necessary configuration options that are supported by the underlying `MessageListenerContainer`.

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

     package com.acme.foo;

     public class MyService {

         @JmsListener(containerFactory = "myJmsListenerContainerFactory", destination="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 `JmsListenerContainerFactory` bean to use. When none is set a `JmsListenerContainerFactory` bean with name `jmsListenerContainerFactory` is assumed to be present.

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

     @Configuration
     @EnableJms
     public class AppConfig {

         @Bean
         public MyService myService() {
             return new MyService();
         }

         // JMS infrastructure setup
     }

Alternatively, if `MyService` were annotated with `@Component`, the following configuration would ensure that its `@JmsListener` annotated method is invoked with a matching incoming message:

     @Configuration
     @EnableJms
     @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 `JmsListenerEndpointRegistry`.

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

     @JmsListener(containerFactory = "myJmsListenerContainerFactory", destination="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 `JmsListenerConfigurer`. This allows access to the underlying `JmsListenerEndpointRegistrar` instance. The following example demonstrates how to specify an explicit default `JmsListenerContainerFactory`

     @Configuration
     @EnableJms
     public class AppConfig implements JmsListenerConfigurer {

         @Override
         public void configureJmsListeners(JmsListenerEndpointRegistrar registrar) {
             registrar.setContainerFactory(myJmsListenerContainerFactory());
         }

         @Bean
         public JmsListenerContainerFactory<?> myJmsListenerContainerFactory() {
             // factory settings
         }

         @Bean
         public MyService myService() {
             return new MyService();
         }
     }

For reference, the example above can be compared to the following Spring XML configuration:

     <beans>

         <jms:annotation-driven container-factory="myJmsListenerContainerFactory"/>

         <bean id="myJmsListenerContainerFactory" class="org.springframework.jms.config.DefaultJmsListenerContainerFactory">
               // factory settings
         </bean>

         <bean id="myService" class="com.acme.foo.MyService"/>

     </beans>
     }

It is also possible to specify a custom `JmsListenerEndpointRegistry` in case you need more control on the way the containers are created and managed. The example below also demonstrates how to customize the `JmsHandlerMethodFactory` to use with a custom `Validator` so that payloads annotated with `Validated` are first validated against a custom `Validator`.

     @Configuration
     @EnableJms
     public class AppConfig implements JmsListenerConfigurer {

         @Override
         public void configureJmsListeners(JmsListenerEndpointRegistrar registrar) {
             registrar.setEndpointRegistry(myJmsListenerEndpointRegistry());
             registrar.setMessageHandlerMethodFactory(myJmsHandlerMethodFactory);
         }

         @Bean
         public JmsListenerEndpointRegistry<?> myJmsListenerEndpointRegistry() {
             // registry configuration
         }

         @Bean
         public JmsHandlerMethodFactory myJmsHandlerMethodFactory() {
            DefaultJmsHandlerMethodFactory factory = new DefaultJmsHandlerMethodFactory();
            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>

         <jms:annotation-driven registry="myJmsListenerEndpointRegistry"
             handler-method-factory="myJmsHandlerMethodFactory"/>

         <bean id="myJmsListenerEndpointRegistry"
               class="org.springframework.jms.config.JmsListenerEndpointRegistry">
               // registry configuration
         </bean>

         <bean id="myJmsHandlerMethodFactory"
               class="org.springframework.messaging.handler.support.DefaultJmsHandlerMethodFactory">
             <property name="validator" ref="myValidator"/>
         </bean>

         <bean id="myService" class="com.acme.foo.MyService"/>

     </beans>

Implementing `JmsListenerConfigurer` also allows for fine-grained control over endpoints registration via the `JmsListenerEndpointRegistrar`. For example, the following configures an extra endpoint:

     @Configuration
     @EnableJms
     public class AppConfig implements JmsListenerConfigurer {

         @Override
         public void configureJmsListeners(JmsListenerEndpointRegistrar registrar) {
             SimpleJmsListenerEndpoint myEndpoint = new SimpleJmsListenerEndpoint();
             // ... configure the endpoint
             registrar.registerEndpoint(endpoint, anotherJmsListenerContainerFactory());
         }

         @Bean
         public MyService myService() {
             return new MyService();
         }

         @Bean
         public JmsListenerContainerFactory<?> anotherJmsListenerContainerFactory() {
             // ...
         }

         // JMS infrastructure setup
     }

Note that all beans implementing `JmsListenerConfigurer` 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:
  4.1
Author:
  Stephane Nicoll
See Also:
  `JmsListener`, `JmsListenerAnnotationBeanPostProcessor`, `JmsListenerEndpointRegistrar`, `JmsListenerEndpointRegistry`