public interface MessageConsumer extends AutoCloseable
MessageConsumer
object to receive messages
from a destination. A MessageConsumer
object is created by
passing a Destination
object to a message-consumer creation
method supplied by a session.
MessageConsumer
is the parent interface for all message
consumers.
A MessageConsumer
can be created with a message selector. A message
selector allows
the client to restrict the messages delivered to the message consumer to
those that match the selector.
A client may either synchronously receive a MessageConsumer
's
messages or have the MessageConsumer
asynchronously deliver them
as they arrive.
For synchronous receipt, a client can request the next message from a
MessageConsumer
using one of its receive
methods. There are several
variations of receive
that allow a client to poll or wait for the next message.
For asynchronous delivery, a client can register a MessageListener
object
with a MessageConsumer
.
As messages arrive at the MessageConsumer
, it delivers them by calling
the MessageListener
's onMessage
method.
It is a client programming error for a MessageListener
to throw an exception.
QueueReceiver
,
TopicSubscriber
,
Session
Modifier and Type | Method and Description |
---|---|
void |
close()
Closes the message consumer.
|
MessageListener |
getMessageListener()
Gets the
MessageConsumer 's MessageListener . |
String |
getMessageSelector()
Gets this message consumer's message selector expression.
|
Message |
receive()
Receives the next message produced for this message consumer.
|
Message |
receive(long timeout)
Receives the next message that arrives within the specified
timeout interval.
|
Message |
receiveNoWait()
Receives the next message if one is immediately available.
|
void |
setMessageListener(MessageListener listener)
Sets the
MessageConsumer 's MessageListener . |
String getMessageSelector() throws JMSException
JMSException
- if the JMS provider fails to get the message
selector due to some internal error.MessageListener getMessageListener() throws JMSException
MessageConsumer
's MessageListener
.
This method must not be used in a Java EE web or EJB application.
Doing so may cause a JMSException
to be thrown though this is not guaranteed.
MessageConsumer
's MessageListener
, or null if one was not setJMSException
- if the JMS provider fails to get the MessageListener
for one of the following reasons:
setMessageListener(javax.jms.MessageListener)
void setMessageListener(MessageListener listener) throws JMSException
MessageConsumer
's MessageListener
.
Setting the the MessageListener
to null is the equivalent of
unsetting the MessageListener
for the MessageConsumer
.
The effect of calling this method
while messages are being consumed by an existing listener
or the MessageConsumer
is being used to consume messages synchronously
is undefined.
This method must not be used in a Java EE web or EJB application.
Doing so may cause a JMSException
to be thrown though this is not guaranteed.
listener
- the listener to which the messages are to be
deliveredJMSException
- if the JMS provider fails to set the MessageConsumer
's MessageListener
for one of the following reasons:
getMessageListener()
Message receive() throws JMSException
This call blocks indefinitely until a message is produced or until this message consumer is closed.
If this receive
is done within a transaction, the
consumer retains the message until the transaction commits.
JMSException
- if the JMS provider fails to receive the next
message due to some internal error.Message receive(long timeout) throws JMSException
This call blocks until a message arrives, the
timeout expires, or this message consumer is closed.
A timeout
of zero never expires, and the call blocks
indefinitely.
timeout
- the timeout value (in milliseconds)JMSException
- if the JMS provider fails to receive the next
message due to some internal error.Message receiveNoWait() throws JMSException
JMSException
- if the JMS provider fails to receive the next
message due to some internal error.void close() throws JMSException
Since a provider may allocate some resources on behalf of a
MessageConsumer
outside the Java virtual machine, clients should
close them when they are not needed. Relying on garbage collection to
eventually reclaim these resources may not be timely enough.
This call will block until a receive
call in progress on this
consumer has completed. A blocked receive
call returns null when
this message consumer is closed.
If this method is called whilst a message listener is in progress in another thread then it will block until the message listener has completed.
This method may be called from a message listener's onMessage
method on its own consumer. After this method returns the
onMessage
method will be allowed to complete normally.
This method is the only MessageConsumer
method that can be called
concurrently.
close
in interface AutoCloseable
JMSException
- if the JMS provider fails to close the consumer due to
some internal error.Copyright © 1996-2013, Oracle and/or its affiliates. All Rights Reserved. Use is subject to license terms.