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/*
 * Copyright 2002-2023 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jms.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.context.annotation.Import;

/**
 * Enable JMS listener annotated endpoints that are created under the cover
 * by a {@link org.springframework.jms.config.JmsListenerContainerFactory
 * JmsListenerContainerFactory}. To be used on
 * {@link org.springframework.context.annotation.Configuration @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 {@code JmsListenerContainerFactory} is responsible for creating the listener * container responsible for a particular endpoint. Typical implementations, as the * {@link org.springframework.jms.config.DefaultJmsListenerContainerFactory DefaultJmsListenerContainerFactory} * used in the sample above, provide the necessary configuration options that are supported by * the underlying {@link org.springframework.jms.listener.MessageListenerContainer MessageListenerContainer}. * *

{@code @EnableJms} enables detection of {@link JmsListener @JmsListener} annotations * on any Spring-managed bean in the container. For example, given a class {@code 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 {@link JmsListener#containerFactory() containerFactory} * attribute defining the name of the {@code JmsListenerContainerFactory} bean to use. When none * is set a {@code JmsListenerContainerFactory} bean with name {@code jmsListenerContainerFactory} is * assumed to be present. * *

The following configuration would ensure that every time a {@link jakarta.jms.Message} * is received on the {@link jakarta.jms.Destination} named "myQueue", {@code MyService.process()} * is invoked with the content of the message: * *

 * @Configuration
 * @EnableJms
 * public class AppConfig {
 *
 *     @Bean
 *     public MyService myService() {
 *         return new MyService();
 *     }
 *
 *     // JMS infrastructure setup
 * }
* *

Alternatively, if {@code MyService} were annotated with {@code @Component}, the * following configuration would ensure that its {@code @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 * {@link org.springframework.jms.config.JmsListenerEndpointRegistry JmsListenerEndpointRegistry}. * *

Annotated methods can use flexible signature; in particular, it is possible to use * the {@link org.springframework.messaging.Message Message} abstraction and related annotations, * see {@link 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 {@link org.springframework.messaging.handler.annotation.support.MessageHandlerMethodFactory} * that is responsible for building the necessary invoker to process the annotated method. By default, * {@link org.springframework.messaging.handler.annotation.support.DefaultMessageHandlerMethodFactory} is used. * *

When more control is desired, a {@code @Configuration} class may implement * {@link JmsListenerConfigurer}. This allows access to the underlying * {@link org.springframework.jms.config.JmsListenerEndpointRegistrar JmsListenerEndpointRegistrar} * instance. The following example demonstrates how to specify an explicit default * {@code 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 {@link org.springframework.jms.config.JmsListenerEndpointRegistry * JmsListenerEndpointRegistry} in case you need more control over the way the containers * are created and managed. The example below also demonstrates how to customize the * {@code JmsHandlerMethodFactory} to use with a custom {@link org.springframework.validation.Validator * Validator} so that payloads annotated with {@link org.springframework.validation.annotation.Validated * Validated} are first validated against a custom {@code 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 {@code JmsListenerConfigurer} also allows for fine-grained * control over endpoint registration via the {@code 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 {@code JmsListenerConfigurer} will be detected and * invoked in a similar fashion. The example above can be translated into a regular bean * definition registered in the context in case you use the XML configuration. * * @author Stephane Nicoll * @since 4.1 * @see JmsListener * @see JmsListenerAnnotationBeanPostProcessor * @see org.springframework.jms.config.JmsListenerEndpointRegistrar * @see org.springframework.jms.config.JmsListenerEndpointRegistry */ @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Import(JmsBootstrapConfiguration.class) public @interface EnableJms { }





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