Package org.springframework.batch.integration.async

Class AsyncItemProcessor<I,O>

java.lang.Object

org.springframework.batch.integration.async.AsyncItemProcessor<I,O>

Type Parameters:

I - the input object type

O - the output object type (will be wrapped in a Future)

All Implemented Interfaces:

ItemProcessor<I,Future<O>>

public class AsyncItemProcessor<I,O>
extends Object
implements ItemProcessor<I,Future<O>>

An ItemProcessor that delegates to a nested processor and in the background. To allow for background processing the return value from the processor is a Future which needs to be unpacked before the item can be used by a client.

Because the Future is typically unwrapped in the ItemWriter, there are lifecycle and stats limitations (since the framework doesn't know what the result of the processor is). While not an exhaustive list, things like StepExecution.getFilterCount() will not reflect the number of filtered items and ItemProcessListener.onProcessError(Object, Exception) will not be called.

Author:

Dave Syer, Mahmoud Ben Hassine

See Also:

• AsyncItemWriter

Constructor Summary

Constructors

Constructor	Description
AsyncItemProcessor(ItemProcessor<I,O> delegate)	Create a new AsyncItemProcessor with the delegate ItemProcessor.

Method Summary

Modifier and Type	Method	Description
@Nullable Future<O>	process(I item)	Transform the input by delegating to the provided item processor.
void	setDelegate(ItemProcessor<I,O> delegate)	The ItemProcessor to use to delegate processing to in a background thread.
void	setTaskExecutor(org.springframework.core.task.TaskExecutor taskExecutor)	The TaskExecutor to use to allow the item processing to proceed in the background.

Methods inherited from class java.lang.Object

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

Constructor Details

AsyncItemProcessor

public AsyncItemProcessor(ItemProcessor<I,O> delegate)

Create a new AsyncItemProcessor with the delegate ItemProcessor.

Parameters:

delegate - the ItemProcessor to use as a delegate

Since:

6.0

Method Details

setDelegate

public void setDelegate(ItemProcessor<I,O> delegate)

The ItemProcessor to use to delegate processing to in a background thread.

Parameters:

delegate - the ItemProcessor to use as a delegate

setTaskExecutor

public void setTaskExecutor(org.springframework.core.task.TaskExecutor taskExecutor)

The TaskExecutor to use to allow the item processing to proceed in the background. Defaults to a SyncTaskExecutor so no threads are created unless this is overridden.

Parameters:

taskExecutor - a TaskExecutor

process

public @Nullable Future<O> process(I item)
                            throws Exception

Transform the input by delegating to the provided item processor. The return value is wrapped in a Future so that clients can unpack it later.

Specified by:

process in interface ItemProcessor<I,O>

Parameters:

item - to be processed, never null.

Returns:

potentially modified or new item for continued processing, null if processing of the provided item should not continue.

Throws:

Exception - thrown if exception occurs during processing.

See Also:

• ItemProcessor.process(Object)