Package org.springframework.batch.integration.support

Class MessageChannelItemReader<T>

java.lang.Object

org.springframework.batch.integration.support.MessageChannelItemReader<T>

Type Parameters:

T - the type of items to be read

All Implemented Interfaces:

ItemReader<T>

public class MessageChannelItemReader<T>
extends Object
implements ItemReader<T>

An ItemReader implementation that receives items as messages from a message channel using a MessagingTemplate. This item reader enables SEDA (Staged Event-Driven Architecture) patterns in Spring Batch jobs by decoupling item production from item consumption through messaging.

Since:

6.0.0

Author:

Mahmoud Ben Hassine

Constructor Summary

Constructors

Constructor	Description
MessageChannelItemReader(org.springframework.integration.core.MessagingTemplate messagingTemplate, Class<T> targetType)	Create a new MessageChannelItemReader instance.
MessageChannelItemReader(org.springframework.integration.core.MessagingTemplate messagingTemplate, org.springframework.messaging.MessageChannel messageChannel, Class<T> targetType)	Create a new MessageChannelItemReader instance.

Method Summary

Modifier and Type	Method	Description
@Nullable T	read()	Reads a piece of input data and advance to the next one.
void	setMessageChannel(org.springframework.messaging.MessageChannel messageChannel)	Set the source message channel.

Methods inherited from class java.lang.Object

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

Constructor Details

MessageChannelItemReader

public MessageChannelItemReader(org.springframework.integration.core.MessagingTemplate messagingTemplate,
 Class<T> targetType)

Create a new MessageChannelItemReader instance. Messages will be read from the default destination of the provided MessagingTemplate which must not be null.

Parameters:

messagingTemplate - the messaging template to use for reading messages

targetType - the target type of items to convert messages to

MessageChannelItemReader

public MessageChannelItemReader(org.springframework.integration.core.MessagingTemplate messagingTemplate,
 org.springframework.messaging.MessageChannel messageChannel,
 Class<T> targetType)

Create a new MessageChannelItemReader instance. Messages will be read from the provided target message channel.

Parameters:

messagingTemplate - the messaging template to use for receiving messages

messageChannel - the message channel to read messages from

targetType - the target type of items to convert messages to

Method Details

setMessageChannel

public void setMessageChannel(org.springframework.messaging.MessageChannel messageChannel)

Set the source message channel.

Parameters:

messageChannel - the message channel to read messages from

read

public @Nullable T read()
                 throws Exception

Description copied from interface: ItemReader

Reads a piece of input data and advance to the next one. Implementations must return null at the end of the input data set. In a transactional setting, caller might get the same item twice from successive calls (or otherwise), if the first call was in a transaction that rolled back.

Specified by:

read in interface ItemReader<T>

Returns:

T the item to be processed or null if the data source is exhausted

Throws:

Exception - if an error occurs.