The JmsTemplate class is the central class in the JMS core package. It simplifies the use of JMS, since it handles the creation and release of resources when sending or synchronously receiving messages.spring-doc.cn

Code that uses the JmsTemplate needs only to implement callback interfaces that give them a clearly defined high-level contract. The MessageCreator callback interface creates a message when given a Session provided by the calling code in JmsTemplate. To allow for more complex usage of the JMS API, SessionCallback provides the JMS session, and ProducerCallback exposes a Session and MessageProducer pair.spring-doc.cn

The JMS API exposes two types of send methods, one that takes delivery mode, priority, and time-to-live as Quality of Service (QOS) parameters and one that takes no QOS parameters and uses default values. Since JmsTemplate has many send methods, setting the QOS parameters have been exposed as bean properties to avoid duplication in the number of send methods. Similarly, the timeout value for synchronous receive calls is set by using the setReceiveTimeout property.spring-doc.cn

Some JMS providers allow the setting of default QOS values administratively through the configuration of the ConnectionFactory. This has the effect that a call to a MessageProducer instance’s send method (send(Destination destination, Message message)) uses different QOS default values than those specified in the JMS specification. In order to provide consistent management of QOS values, the JmsTemplate must, therefore, be specifically enabled to use its own QOS values by setting the boolean property isExplicitQosEnabled to true.spring-doc.cn

For convenience, JmsTemplate also exposes a basic request-reply operation that allows for sending a message and waiting for a reply on a temporary queue that is created as part of the operation.spring-doc.cn

As of Spring Framework 4.1, JmsMessagingTemplate is built on top of JmsTemplate and provides an integration with the messaging abstraction — that is, org.springframework.messaging.Message. This lets you create the message to send in a generic manner.spring-doc.cn

The JmsTemplate requires a reference to a ConnectionFactory. The ConnectionFactory is part of the JMS specification and serves as the entry point for working with JMS. It is used by the client application as a factory to create connections with the JMS provider and encapsulates various configuration parameters, many of which are vendor-specific, such as SSL configuration options.spring-doc.cn

When using JMS inside an EJB, the vendor provides implementations of the JMS interfaces so that they can participate in declarative transaction management and perform pooling of connections and sessions. In order to use this implementation, Jakarta EE containers typically require that you declare a JMS connection factory as a resource-ref inside the EJB or servlet deployment descriptors. To ensure the use of these features with the JmsTemplate inside an EJB, the client application should ensure that it references the managed implementation of the ConnectionFactory.spring-doc.cn

Destinations, as ConnectionFactory instances, are JMS administered objects that you can store and retrieve in JNDI. When configuring a Spring application context, you can use the JNDI JndiObjectFactoryBean factory class or <jee:jndi-lookup> to perform dependency injection on your object’s references to JMS destinations. However, this strategy is often cumbersome if there are a large number of destinations in the application or if there are advanced destination management features unique to the JMS provider. Examples of such advanced destination management include the creation of dynamic destinations or support for a hierarchical namespace of destinations. The JmsTemplate delegates the resolution of a destination name to a JMS destination object that implements the DestinationResolver interface. DynamicDestinationResolver is the default implementation used by JmsTemplate and accommodates resolving dynamic destinations. A JndiDestinationResolver is also provided to act as a service locator for destinations contained in JNDI and optionally falls back to the behavior contained in DynamicDestinationResolver.spring-doc.cn

Quite often, the destinations used in a JMS application are only known at runtime and, therefore, cannot be administratively created when the application is deployed. This is often because there is shared application logic between interacting system components that create destinations at runtime according to a well-known naming convention. Even though the creation of dynamic destinations is not part of the JMS specification, most vendors have provided this functionality. Dynamic destinations are created with a user-defined name, which differentiates them from temporary destinations, and are often not registered in JNDI. The API used to create dynamic destinations varies from provider to provider since the properties associated with the destination are vendor-specific. However, a simple implementation choice that is sometimes made by vendors is to disregard the warnings in the JMS specification and to use the method TopicSession createTopic(String topicName) or the QueueSession createQueue(String queueName) method to create a new destination with default destination properties. Depending on the vendor implementation, DynamicDestinationResolver can then also create a physical destination instead of only resolving one.spring-doc.cn

The boolean property pubSubDomain is used to configure the JmsTemplate with knowledge of what JMS domain is being used. By default, the value of this property is false, indicating that the point-to-point domain, Queues, is to be used. This property (used by JmsTemplate) determines the behavior of dynamic destination resolution through implementations of the DestinationResolver interface.spring-doc.cn

You can also configure the JmsTemplate with a default destination through the property defaultDestination. The default destination is with send and receive operations that do not refer to a specific destination.spring-doc.cn

One of the most common uses of JMS messages in the EJB world is to drive message-driven beans (MDBs). Spring offers a solution to create message-driven POJOs (MDPs) in a way that does not tie a user to an EJB container. (See Asynchronous reception: Message-Driven POJOs for detailed coverage of Spring’s MDP support.) Since Spring Framework 4.1, endpoint methods can be annotated with @JmsListener — see Annotation-driven Listener Endpoints for more details.spring-doc.cn

A message listener container is used to receive messages from a JMS message queue and drive the MessageListener that is injected into it. The listener container is responsible for all threading of message reception and dispatches into the listener for processing. A message listener container is the intermediary between an MDP and a messaging provider and takes care of registering to receive messages, participating in transactions, resource acquisition and release, exception conversion, and so on. This lets you write the (possibly complex) business logic associated with receiving a message (and possibly respond to it), and delegates boilerplate JMS infrastructure concerns to the framework.spring-doc.cn

There are two standard JMS message listener containers packaged with Spring, each with its specialized feature set.spring-doc.cn

Spring provides a JmsTransactionManager that manages transactions for a single JMS ConnectionFactory. This lets JMS applications leverage the managed-transaction features of Spring, as described in Transaction Management section of the Data Access chapter. The JmsTransactionManager performs local resource transactions, binding a JMS Connection/Session pair from the specified ConnectionFactory to the thread. JmsTemplate automatically detects such transactional resources and operates on them accordingly.spring-doc.cn

In a Jakarta EE environment, the ConnectionFactory pools Connection and Session instances, so those resources are efficiently reused across transactions. In a standalone environment, using Spring’s SingleConnectionFactory result in a shared JMS Connection, with each transaction having its own independent Session. Alternatively, consider the use of a provider-specific pooling adapter, such as ActiveMQ’s PooledConnectionFactory class.spring-doc.cn

You can also use JmsTemplate with the JtaTransactionManager and an XA-capable JMS ConnectionFactory to perform distributed transactions. Note that this requires the use of a JTA transaction manager as well as a properly XA-configured ConnectionFactory. (Check your Jakarta EE server’s or JMS provider’s documentation.)spring-doc.cn

Reusing code across a managed and unmanaged transactional environment can be confusing when using the JMS API to create a Session from a Connection. This is because the JMS API has only one factory method to create a Session, and it requires values for the transaction and acknowledgment modes. In a managed environment, setting these values is the responsibility of the environment’s transactional infrastructure, so these values are ignored by the vendor’s wrapper to the JMS Connection. When you use the JmsTemplate in an unmanaged environment, you can specify these values through the use of the properties sessionTransacted and sessionAcknowledgeMode. When you use a PlatformTransactionManager with JmsTemplate, the template is always given a transactional JMS Session.spring-doc.cn