JMS API 2.0.1 · javax.jms.MessageConsumer

A client uses a 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.

Method Summary

Modifier and Type	Method and Description
public void	close() Redeclares java.lang.AutoCloseable.close. Closes the message consumer.
public MessageListener	Returns: the `MessageConsumer`'s `MessageListener`, or null if one was not set getMessageListener() Gets the `MessageConsumer`'s `MessageListener`.
public String	Returns: this message consumer's message selector, or null if no message selector exists for the message consumer (that is, if the message selector was not set or was set to null or the empty string) getMessageSelector() Gets this message consumer's message selector expression.
public Message	Returns: the next message produced for this message consumer, or null if this message consumer is concurrently closed receive() Receives the next message produced for this message consumer.
public Message	Returns: the next message produced for this message consumer, or null if the timeout expires or this message consumer is concurrently closed receive(long the timeout value (in milliseconds) timeout) Receives the next message that arrives within the specified timeout interval.
public Message	Returns: the next message produced for this message consumer, or null if one is not available receiveNoWait() Receives the next message if one is immediately available.
public void	setMessageListener(MessageListener the listener to which the messages are to be delivered listener) Sets the `MessageConsumer`'s `MessageListener`.

Method Detail

close back to summary

close	back to summary
public void close() throws JMSException Redeclares java.lang.AutoCloseable.close. Closes the message consumer. 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. Exceptions JMSException: if the JMS provider fails to close the consumer due to some internal error.

public void close() throws JMSException

Redeclares java.lang.AutoCloseable.close.

Closes the message consumer.

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.

Exceptions

JMSException:: if the JMS provider fails to close the consumer due to some internal error.

getMessageListener back to summary

getMessageListener	back to summary
public MessageListener getMessageListener() throws JMSException Gets the `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. Returns:MessageListener the `MessageConsumer`'s `MessageListener`, or null if one was not set Exceptions JMSException: if the JMS provider fails to get the `MessageListener` for one of the following reasons: an internal error has occurred or this method has been called in a Java EE web or EJB application (though it is not guaranteed that an exception is thrown in this case) See Also `javax.jms.MessageConsumer#setMessageListener(javax.jms.MessageListener)`

public MessageListener getMessageListener() throws JMSException

Gets the 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.

Returns:MessageListener

the MessageConsumer's MessageListener, or null if one was not set

Exceptions

JMSException:

if the JMS provider fails to get the MessageListener for one of the following reasons:

an internal error has occurred or
this method has been called in a Java EE web or EJB application (though it is not guaranteed that an exception is thrown in this case)

getMessageSelector	back to summary
public String getMessageSelector() throws JMSException Gets this message consumer's message selector expression. Returns:String this message consumer's message selector, or null if no message selector exists for the message consumer (that is, if the message selector was not set or was set to null or the empty string) Exceptions JMSException: if the JMS provider fails to get the message selector due to some internal error.

getMessageSelector

back to summary

public String getMessageSelector() throws JMSException

Gets this message consumer's message selector expression.

Returns:String

this message consumer's message selector, or null if no message selector exists for the message consumer (that is, if the message selector was not set or was set to null or the empty string)

Exceptions

JMSException:: if the JMS provider fails to get the message selector due to some internal error.

receive back to summary

receive	back to summary
public Message receive() throws JMSException Receives the next message produced for this message consumer. 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. Returns:Message the next message produced for this message consumer, or null if this message consumer is concurrently closed Exceptions JMSException: if the JMS provider fails to receive the next message due to some internal error.

public Message receive() throws JMSException

Receives the next message produced for this message consumer.

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.

Returns:Message

the next message produced for this message consumer, or null if this message consumer is concurrently closed

Exceptions

JMSException:: if the JMS provider fails to receive the next message due to some internal error.

receive back to summary

receive	back to summary
public Message receive(long timeout) throws JMSException Receives the next message that arrives within the specified timeout interval. 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. Parameters timeout:long the timeout value (in milliseconds) Returns:Message the next message produced for this message consumer, or null if the timeout expires or this message consumer is concurrently closed Exceptions JMSException: if the JMS provider fails to receive the next message due to some internal error.

public Message receive(long timeout) throws JMSException

Receives the next message that arrives within the specified timeout interval.

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.

Parameters

timeout:long: the timeout value (in milliseconds)

Returns:Message

the next message produced for this message consumer, or null if the timeout expires or this message consumer is concurrently closed

Exceptions

JMSException:: if the JMS provider fails to receive the next message due to some internal error.

receiveNoWait	back to summary
public Message receiveNoWait() throws JMSException Receives the next message if one is immediately available. Returns:Message the next message produced for this message consumer, or null if one is not available Exceptions JMSException: if the JMS provider fails to receive the next message due to some internal error.

receiveNoWait

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public Message receiveNoWait() throws JMSException

Receives the next message if one is immediately available.

Returns:Message

the next message produced for this message consumer, or null if one is not available

Exceptions

JMSException:: if the JMS provider fails to receive the next message due to some internal error.

setMessageListener back to summary

setMessageListener	back to summary
public void setMessageListener(MessageListener listener) throws JMSException Sets the `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. Parameters listener:MessageListener the listener to which the messages are to be delivered Exceptions JMSException: if the JMS provider fails to set the `MessageConsumer`'s `MessageListener` for one of the following reasons: an internal error has occurred or this method has been called in a Java EE web or EJB application (though it is not guaranteed that an exception is thrown in this case) See Also `javax.jms.MessageConsumer#getMessageListener()`

public void setMessageListener(MessageListener listener) throws JMSException

Sets the 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.

Parameters

listener:MessageListener: the listener to which the messages are to be delivered

Exceptions

JMSException:

if the JMS provider fails to set the MessageConsumer's MessageListener for one of the following reasons:

an internal error has occurred or
this method has been called in a Java EE web or EJB application (though it is not guaranteed that an exception is thrown in this case)

public Interface MessageConsumer

Method Summary

Method Detail