Package org.springframework.batch.item.queue

Class BlockingQueueItemReader<T>

java.lang.Object

org.springframework.batch.item.queue.BlockingQueueItemReader<T>

Type Parameters:

T - type of items to read.

All Implemented Interfaces:

ItemReader<@NonNull T>

public class BlockingQueueItemReader<T>
extends Object
implements ItemReader<@NonNull T>

This is an ItemReader that reads items from a BlockingQueue. It stops reading (i.e., returns null) if no items are available in the queue after a configurable timeout.

Since:

5.2.0

Author:

Mahmoud Ben Hassine

Constructor Summary

Constructors

Constructor	Description
BlockingQueueItemReader(BlockingQueue<T> queue)	Create a new BlockingQueueItemReader.

Method Summary

Modifier and Type	Method	Description
@Nullable T	read()	Reads a piece of input data and advance to the next one.
void	setTimeout(long timeout, TimeUnit timeUnit)	Set the reading timeout and time unit.

Methods inherited from class java.lang.Object

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

Constructor Details

BlockingQueueItemReader

public BlockingQueueItemReader(BlockingQueue<T> queue)

Create a new BlockingQueueItemReader.

Parameters:

queue - the queue to read items from

Method Details

setTimeout

public void setTimeout(long timeout,
 TimeUnit timeUnit)

Set the reading timeout and time unit. Defaults to 1 second.

Parameters:

timeout - the timeout after which the reader stops reading

timeUnit - the unit of the timeout

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:

ParseException - if there is a problem parsing the current record (but the next one may still be valid)

NonTransientResourceException - if there is a fatal exception in the underlying resource. After throwing this exception implementations should endeavour to return null from subsequent calls to read.

UnexpectedInputException - if there is an uncategorised problem with the input data. Assume potentially transient, so subsequent calls to read might succeed.

Exception - if an there is a non-specific error.