org.springframework.batch.item.support

Class SynchronizedItemStreamReader<T>

java.lang.Object

org.springframework.batch.item.support.SynchronizedItemStreamReader<T>

Type Parameters:

T - type of object being read

All Implemented Interfaces:

ItemReader<T>, ItemStream, ItemStreamReader<T>, org.springframework.beans.factory.InitializingBean

public class SynchronizedItemStreamReader<T>
extends java.lang.Object
implements ItemStreamReader<T>, org.springframework.beans.factory.InitializingBean

This is a simple ItemStreamReader decorator with a synchronized ItemReader.read() method - which makes a non-thread-safe ItemReader thread-safe. However, if reprocessing an item is problematic then using this will make a job not restartable. Here are some links about the motivation behind this class: - http://projects.spring.io/spring-batch/faq.html#threading-reader} - http://stackoverflow.com/a/20002493/2910265}

Since:

3.0.4

Author:

Matthew Ouyang

Constructor Summary

Constructors

Constructor and Description
SynchronizedItemStreamReader()

Method Summary

Modifier and Type	Method and Description
void	afterPropertiesSet()
void	close() If any resources are needed for the stream to operate they need to be destroyed here.
void	open(ExecutionContext executionContext) Open the stream for the provided ExecutionContext.
T	read() This delegates to the read method of the delegate
void	setDelegate(ItemStreamReader<T> delegate)
void	update(ExecutionContext executionContext) Indicates that the execution context provided during open is about to be saved.

Methods inherited from class java.lang.Object

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

Constructor Detail

SynchronizedItemStreamReader

public SynchronizedItemStreamReader()

Method Detail

setDelegate

public void setDelegate(ItemStreamReader<T> delegate)

read

public T read()
       throws java.lang.Exception,
              UnexpectedInputException,
              ParseException,
              NonTransientResourceException

This delegates to the read method of the delegate

Specified by:

read in interface ItemReader<T>

Returns:

T the item to be processed

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.

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

close

public void close()

Description copied from interface: ItemStream

If any resources are needed for the stream to operate they need to be destroyed here. Once this method has been called all other methods (except open) may throw an exception.

Specified by:

close in interface ItemStream

open

public void open(ExecutionContext executionContext)

Description copied from interface: ItemStream

Open the stream for the provided ExecutionContext.

Specified by:

open in interface ItemStream

Parameters:

executionContext - current step's ExecutionContext. Will be the executionContext from the last run of the step on a restart.

update

public void update(ExecutionContext executionContext)

Description copied from interface: ItemStream

Indicates that the execution context provided during open is about to be saved. If any state is remaining, but has not been put in the context, it should be added here.

Specified by:

update in interface ItemStream

Parameters:

executionContext - to be updated

afterPropertiesSet

public void afterPropertiesSet()
                        throws java.lang.Exception

Specified by:

afterPropertiesSet in interface org.springframework.beans.factory.InitializingBean

Throws:

java.lang.Exception