org.springframework.jms.listener.adapter

Class MessageListenerAdapter

java.lang.Object

org.springframework.jms.listener.adapter.MessageListenerAdapter

All Implemented Interfaces:

MessageListener, SessionAwareMessageListener<Message>, SubscriptionNameProvider

public class MessageListenerAdapter
extends Object
implements MessageListener, SessionAwareMessageListener<Message>, SubscriptionNameProvider

Message listener adapter that delegates the handling of messages to target listener methods via reflection, with flexible message type conversion. Allows listener methods to operate on message content types, completely independent from the JMS API.

By default, the content of incoming JMS messages gets extracted before being passed into the target listener method, to let the target method operate on message content types such as String or byte array instead of the raw Message. Message type conversion is delegated to a Spring JMS MessageConverter. By default, a SimpleMessageConverter will be used. (If you do not want such automatic message conversion taking place, then be sure to set the MessageConverter to null.)

If a target listener method returns a non-null object (typically of a message content type such as String or byte array), it will get wrapped in a JMS Message and sent to the response destination (either the JMS "reply-to" destination or a specified default destination).

Note: The sending of response messages is only available when using the SessionAwareMessageListener entry point (typically through a Spring message listener container). Usage as standard JMS MessageListener does not support the generation of response messages.

Find below some examples of method signatures compliant with this adapter class. This first example handles all Message types and gets passed the contents of each Message type as an argument. No Message will be sent back as all of these methods return void.

public interface MessageContentsDelegate {
    void handleMessage(String text);
    void handleMessage(Map map);
    void handleMessage(byte[] bytes);
    void handleMessage(Serializable obj);
 }

This next example handles all Message types and gets passed the actual (raw) Message as an argument. Again, no Message will be sent back as all of these methods return void.

public interface RawMessageDelegate {
    void handleMessage(TextMessage message);
    void handleMessage(MapMessage message);
    void handleMessage(BytesMessage message);
    void handleMessage(ObjectMessage message);
 }

This next example illustrates a Message delegate that just consumes the String contents of TextMessages. Notice also how the name of the Message handling method is different from the original (this will have to be configured in the attandant bean definition). Again, no Message will be sent back as the method returns void.

public interface TextMessageContentDelegate {
    void onMessage(String text);
 }

This final example illustrates a Message delegate that just consumes the String contents of TextMessages. Notice how the return type of this method is String: This will result in the configured MessageListenerAdapter sending a TextMessage in response.

public interface ResponsiveTextMessageContentDelegate {
    String handleMessage(String text);
 }

For further examples and discussion please do refer to the Spring reference documentation which describes this class (and it's attendant XML configuration) in detail.

Since:

2.0

Author:

Juergen Hoeller

See Also:

setDelegate(java.lang.Object), setDefaultListenerMethod(java.lang.String), setDefaultResponseDestination(javax.jms.Destination), setMessageConverter(org.springframework.jms.support.converter.MessageConverter), SimpleMessageConverter, SessionAwareMessageListener, AbstractMessageListenerContainer.setMessageListener(java.lang.Object)

Field Summary

Fields

Modifier and Type	Field and Description
protected Log	logger Logger available to subclasses
static String	ORIGINAL_DEFAULT_LISTENER_METHOD Out-of-the-box value for the default listener method: "handleMessage".

Constructor Summary

Constructors

Constructor and Description
MessageListenerAdapter() Create a new MessageListenerAdapter with default settings.
MessageListenerAdapter(Object delegate) Create a new MessageListenerAdapter for the given delegate.

Method Summary

Modifier and Type	Method and Description
protected Object[]	buildListenerArguments(Object extractedMessage) Build an array of arguments to be passed into the target listener method.
protected Message	buildMessage(Session session, Object result) Build a JMS message to be sent as response based on the given result object.
protected Object	extractMessage(Message message) Extract the message body from the given JMS message.
protected String	getDefaultListenerMethod() Return the name of the default listener method to delegate to.
protected Object	getDelegate() Return the target object to delegate message listening to.
protected DestinationResolver	getDestinationResolver() Return the DestinationResolver for this adapter.
protected String	getListenerMethodName(Message originalMessage, Object extractedMessage) Determine the name of the listener method that is supposed to handle the given message.
protected MessageConverter	getMessageConverter() Return the converter that will convert incoming JMS messages to listener method arguments, and objects returned from listener methods back to JMS messages.
protected Destination	getResponseDestination(Message request, Message response, Session session) Determine a response destination for the given message.
String	getSubscriptionName() Determine the subscription name for this message listener object.
protected void	handleListenerException(Throwable ex) Handle the given exception that arose during listener execution.
protected void	handleResult(Object result, Message request, Session session) Handle the given result object returned from the listener method, sending a response message back.
protected void	initDefaultStrategies() Initialize the default implementations for the adapter's strategies.
protected Object	invokeListenerMethod(String methodName, Object[] arguments) Invoke the specified listener method.
void	onMessage(Message message) Standard JMS MessageListener entry point.
void	onMessage(Message message, Session session) Spring SessionAwareMessageListener entry point.
protected void	postProcessProducer(MessageProducer producer, Message response) Post-process the given message producer before using it to send the response.
protected void	postProcessResponse(Message request, Message response) Post-process the given response message before it will be sent.
protected Destination	resolveDefaultResponseDestination(Session session) Resolve the default response destination into a JMS Destination, using this accessor's DestinationResolver in case of a destination name.
protected void	sendResponse(Session session, Destination destination, Message response) Send the given response message to the given destination.
void	setDefaultListenerMethod(String defaultListenerMethod) Specify the name of the default listener method to delegate to, for the case where no specific listener method has been determined.
void	setDefaultResponseDestination(Destination destination) Set the default destination to send response messages to.
void	setDefaultResponseQueueName(String destinationName) Set the name of the default response queue to send response messages to.
void	setDefaultResponseTopicName(String destinationName) Set the name of the default response topic to send response messages to.
void	setDelegate(Object delegate) Set a target object to delegate message listening to.
void	setDestinationResolver(DestinationResolver destinationResolver) Set the DestinationResolver that should be used to resolve response destination names for this adapter.
void	setMessageConverter(MessageConverter messageConverter) Set the converter that will convert incoming JMS messages to listener method arguments, and objects returned from listener methods back to JMS messages.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ORIGINAL_DEFAULT_LISTENER_METHOD

public static final String ORIGINAL_DEFAULT_LISTENER_METHOD

Out-of-the-box value for the default listener method: "handleMessage".

See Also:

Constant Field Values

logger

protected final Log logger

Logger available to subclasses

Constructor Detail

MessageListenerAdapter

public MessageListenerAdapter()

Create a new MessageListenerAdapter with default settings.

MessageListenerAdapter

public MessageListenerAdapter(Object delegate)

Create a new MessageListenerAdapter for the given delegate.

Parameters:

delegate - the delegate object

Method Detail

setDelegate

public void setDelegate(Object delegate)

Set a target object to delegate message listening to. Specified listener methods have to be present on this target object.

If no explicit delegate object has been specified, listener methods are expected to present on this adapter instance, that is, on a custom subclass of this adapter, defining listener methods.

getDelegate

protected Object getDelegate()

Return the target object to delegate message listening to.

setDefaultListenerMethod

public void setDefaultListenerMethod(String defaultListenerMethod)

Specify the name of the default listener method to delegate to, for the case where no specific listener method has been determined. Out-of-the-box value is "handleMessage".

See Also:

getListenerMethodName(javax.jms.Message, java.lang.Object)

getDefaultListenerMethod

protected String getDefaultListenerMethod()

Return the name of the default listener method to delegate to.

setDefaultResponseDestination

public void setDefaultResponseDestination(Destination destination)

Set the default destination to send response messages to. This will be applied in case of a request message that does not carry a "JMSReplyTo" field.

Response destinations are only relevant for listener methods that return result objects, which will be wrapped in a response message and sent to a response destination.

Alternatively, specify a "defaultResponseQueueName" or "defaultResponseTopicName", to be dynamically resolved via the DestinationResolver.

See Also:

setDefaultResponseQueueName(String), setDefaultResponseTopicName(String), getResponseDestination(javax.jms.Message, javax.jms.Message, javax.jms.Session)

setDefaultResponseQueueName

public void setDefaultResponseQueueName(String destinationName)

Set the name of the default response queue to send response messages to. This will be applied in case of a request message that does not carry a "JMSReplyTo" field.

Alternatively, specify a JMS Destination object as "defaultResponseDestination".

See Also:

setDestinationResolver(org.springframework.jms.support.destination.DestinationResolver), setDefaultResponseDestination(javax.jms.Destination)

setDefaultResponseTopicName

public void setDefaultResponseTopicName(String destinationName)

Set the name of the default response topic to send response messages to. This will be applied in case of a request message that does not carry a "JMSReplyTo" field.

Alternatively, specify a JMS Destination object as "defaultResponseDestination".

See Also:

setDestinationResolver(org.springframework.jms.support.destination.DestinationResolver), setDefaultResponseDestination(javax.jms.Destination)

setDestinationResolver

public void setDestinationResolver(DestinationResolver destinationResolver)

Set the DestinationResolver that should be used to resolve response destination names for this adapter.

The default resolver is a DynamicDestinationResolver. Specify a JndiDestinationResolver for resolving destination names as JNDI locations.

See Also:

DynamicDestinationResolver, JndiDestinationResolver

getDestinationResolver

protected DestinationResolver getDestinationResolver()

Return the DestinationResolver for this adapter.

setMessageConverter

public void setMessageConverter(MessageConverter messageConverter)

Set the converter that will convert incoming JMS messages to listener method arguments, and objects returned from listener methods back to JMS messages.

The default converter is a SimpleMessageConverter, which is able to handle BytesMessages, TextMessages and ObjectMessages.

getMessageConverter

protected MessageConverter getMessageConverter()

Return the converter that will convert incoming JMS messages to listener method arguments, and objects returned from listener methods back to JMS messages.

onMessage

public void onMessage(Message message)

Standard JMS MessageListener entry point.

Delegates the message to the target listener method, with appropriate conversion of the message argument. In case of an exception, the handleListenerException(Throwable) method will be invoked.

Note: Does not support sending response messages based on result objects returned from listener methods. Use the SessionAwareMessageListener entry point (typically through a Spring message listener container) for handling result objects as well.

Specified by:

onMessage in interface MessageListener

Parameters:

message - the incoming JMS message

See Also:

handleListenerException(java.lang.Throwable), onMessage(javax.jms.Message, javax.jms.Session)

onMessage

public void onMessage(Message message,
                      Session session)
               throws JMSException

Spring SessionAwareMessageListener entry point.

Delegates the message to the target listener method, with appropriate conversion of the message argument. If the target method returns a non-null object, wrap in a JMS message and send it back.

Specified by:

onMessage in interface SessionAwareMessageListener<Message>

Parameters:

message - the incoming JMS message

session - the JMS session to operate on

Throws:

JMSException - if thrown by JMS API methods

getSubscriptionName

public String getSubscriptionName()

Description copied from interface: SubscriptionNameProvider

Determine the subscription name for this message listener object.

Specified by:

getSubscriptionName in interface SubscriptionNameProvider

initDefaultStrategies

protected void initDefaultStrategies()

Initialize the default implementations for the adapter's strategies.

See Also:

setMessageConverter(org.springframework.jms.support.converter.MessageConverter), SimpleMessageConverter

handleListenerException

protected void handleListenerException(Throwable ex)

Handle the given exception that arose during listener execution. The default implementation logs the exception at error level.

This method only applies when used as standard JMS MessageListener. In case of the Spring SessionAwareMessageListener mechanism, exceptions get handled by the caller instead.

Parameters:

ex - the exception to handle

See Also:

onMessage(javax.jms.Message)

extractMessage

protected Object extractMessage(Message message)
                         throws JMSException

Extract the message body from the given JMS message.

Parameters:

message - the JMS Message

Returns:

the content of the message, to be passed into the listener method as argument

Throws:

JMSException - if thrown by JMS API methods

getListenerMethodName

protected String getListenerMethodName(Message originalMessage,
                                       Object extractedMessage)
                                throws JMSException

Determine the name of the listener method that is supposed to handle the given message.

The default implementation simply returns the configured default listener method, if any.

Parameters:

originalMessage - the JMS request message

extractedMessage - the converted JMS request message, to be passed into the listener method as argument

Returns:

the name of the listener method (never null)

Throws:

JMSException - if thrown by JMS API methods

See Also:

setDefaultListenerMethod(java.lang.String)

buildListenerArguments

protected Object[] buildListenerArguments(Object extractedMessage)

Build an array of arguments to be passed into the target listener method. Allows for multiple method arguments to be built from a single message object.

The default implementation builds an array with the given message object as sole element. This means that the extracted message will always be passed into a single method argument, even if it is an array, with the target method having a corresponding single argument of the array's type declared.

This can be overridden to treat special message content such as arrays differently, for example passing in each element of the message array as distinct method argument.

Parameters:

extractedMessage - the content of the message

Returns:

the array of arguments to be passed into the listener method (each element of the array corresponding to a distinct method argument)

invokeListenerMethod

protected Object invokeListenerMethod(String methodName,
                                      Object[] arguments)
                               throws JMSException

Invoke the specified listener method.

Parameters:

methodName - the name of the listener method

arguments - the message arguments to be passed in

Returns:

the result returned from the listener method

Throws:

JMSException - if thrown by JMS API methods

See Also:

getListenerMethodName(javax.jms.Message, java.lang.Object), buildListenerArguments(java.lang.Object)

handleResult

protected void handleResult(Object result,
                            Message request,
                            Session session)
                     throws JMSException

Handle the given result object returned from the listener method, sending a response message back.

Parameters:

result - the result object to handle (never null)

request - the original request message

session - the JMS Session to operate on (may be null)

Throws:

JMSException - if thrown by JMS API methods

See Also:

buildMessage(javax.jms.Session, java.lang.Object), postProcessResponse(javax.jms.Message, javax.jms.Message), getResponseDestination(javax.jms.Message, javax.jms.Message, javax.jms.Session), sendResponse(javax.jms.Session, javax.jms.Destination, javax.jms.Message)

buildMessage

protected Message buildMessage(Session session,
                               Object result)
                        throws JMSException

Build a JMS message to be sent as response based on the given result object.

Parameters:

session - the JMS Session to operate on

result - the content of the message, as returned from the listener method

Returns:

the JMS Message (never null)

Throws:

JMSException - if thrown by JMS API methods

See Also:

setMessageConverter(org.springframework.jms.support.converter.MessageConverter)

postProcessResponse

protected void postProcessResponse(Message request,
                                   Message response)
                            throws JMSException

Post-process the given response message before it will be sent.

The default implementation sets the response's correlation id to the request message's correlation id, if any; otherwise to the request message id.

Parameters:

request - the original incoming JMS message

response - the outgoing JMS message about to be sent

Throws:

JMSException - if thrown by JMS API methods

See Also:

Message.setJMSCorrelationID(java.lang.String)

getResponseDestination

protected Destination getResponseDestination(Message request,
                                             Message response,
                                             Session session)
                                      throws JMSException

Determine a response destination for the given message.

The default implementation first checks the JMS Reply-To Destination of the supplied request; if that is not null it is returned; if it is null, then the configured default response destination is returned; if this too is null, then an InvalidDestinationException is thrown.

Parameters:

request - the original incoming JMS message

response - the outgoing JMS message about to be sent

session - the JMS Session to operate on

Returns:

the response destination (never null)

Throws:

JMSException - if thrown by JMS API methods

InvalidDestinationException - if no Destination can be determined

See Also:

setDefaultResponseDestination(javax.jms.Destination), Message.getJMSReplyTo()

resolveDefaultResponseDestination

protected Destination resolveDefaultResponseDestination(Session session)
                                                 throws JMSException

Resolve the default response destination into a JMS Destination, using this accessor's DestinationResolver in case of a destination name.

Returns:

the located Destination

Throws:

JMSException - if resolution failed

See Also:

setDefaultResponseDestination(javax.jms.Destination), setDefaultResponseQueueName(java.lang.String), setDefaultResponseTopicName(java.lang.String), setDestinationResolver(org.springframework.jms.support.destination.DestinationResolver)

sendResponse

protected void sendResponse(Session session,
                            Destination destination,
                            Message response)
                     throws JMSException

Send the given response message to the given destination.

Parameters:

response - the JMS message to send

destination - the JMS destination to send to

session - the JMS session to operate on

Throws:

JMSException - if thrown by JMS API methods

See Also:

postProcessProducer(javax.jms.MessageProducer, javax.jms.Message), Session.createProducer(javax.jms.Destination), MessageProducer.send(javax.jms.Message)

postProcessProducer

protected void postProcessProducer(MessageProducer producer,
                                   Message response)
                            throws JMSException

Post-process the given message producer before using it to send the response.

The default implementation is empty.

Parameters:

producer - the JMS message producer that will be used to send the message

response - the outgoing JMS message about to be sent

Throws:

JMSException - if thrown by JMS API methods