org.springframework.batch.core.step.item
Class ItemSkipPolicyItemHandler

java.lang.Object
  org.springframework.batch.core.step.item.SimpleItemHandler
      org.springframework.batch.core.step.item.ItemSkipPolicyItemHandler

All Implemented Interfaces:

ItemHandler

public class ItemSkipPolicyItemHandler
extends SimpleItemHandler

ItemHandler that implements skip behavior. It delegates to setItemSkipPolicy(ItemSkipPolicy) to decide whether skip should be called or not. If exception is thrown while reading the item, skip is called on the ItemReader. If exception is thrown while writing the item, skip is called on both ItemReader and ItemWriter.

Author:

Dave Syer, Robert Kasanicky

Field Summary

protected org.apache.commons.logging.Log

logger

Constructor Summary

ItemSkipPolicyItemHandler(ItemReader itemReader, ItemWriter itemWriter)

Method Summary

protected void	doWriteWithSkip(Object item, StepContribution contribution)
void	mark() Implementations should delegate to an ItemReader.
protected Object	read(StepContribution contribution) Tries to read the item from the reader, in case of exception skip the item if the skip policy allows, otherwise re-throw.
void	registerSkipListener(SkipListener listener) Register a listener for callbacks at the appropriate stages in a skip process.
void	setItemKeyGenerator(ItemKeyGenerator itemKeyGenerator) Public setter for the ItemKeyGenerator.
void	setItemSkipPolicy(ItemSkipPolicy itemSkipPolicy)
void	setSkipCacheCapacity(int skipCacheCapacity) Public setter for the capacity of the skipped item cache.
void	setSkipListeners(SkipListener[] listeners) Register some SkipListeners with the handler.
protected void	write(Object item, StepContribution contribution) Tries to write the item using the writer.

Methods inherited from class org.springframework.batch.core.step.item.SimpleItemHandler

clear, doRead, doWrite, flush, handle, reset

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected final org.apache.commons.logging.Log logger

Constructor Detail

ItemSkipPolicyItemHandler

public ItemSkipPolicyItemHandler(ItemReader itemReader,
                                 ItemWriter itemWriter)

Parameters:

itemReader -

itemWriter -

Method Detail

setSkipListeners

public void setSkipListeners(SkipListener[] listeners)

Register some SkipListeners with the handler. Each will get the callbacks in the order specified at the correct stage if a skip occurs.

Parameters:

listeners -

registerSkipListener

public void registerSkipListener(SkipListener listener)

Register a listener for callbacks at the appropriate stages in a skip process.

Parameters:

listener - a SkipListener

setItemKeyGenerator

public void setItemKeyGenerator(ItemKeyGenerator itemKeyGenerator)

Public setter for the ItemKeyGenerator. Defaults to just return the item, and since it will be used before a write operation. Implementations must ensure that items always have the same key when they are read from the ItemReader (so if the item is mutable and the reader does any buffering the key generator might need to take care to only use data that do not change on write).

Parameters:

itemKeyGenerator - the ItemKeyGenerator to set. If null resets to default value.

setItemSkipPolicy

public void setItemSkipPolicy(ItemSkipPolicy itemSkipPolicy)

Parameters:

itemSkipPolicy -

setSkipCacheCapacity

public void setSkipCacheCapacity(int skipCacheCapacity)

Public setter for the capacity of the skipped item cache. If a large number of items are failing and not being recognized as skipped, it usually signals a problem with the key generation (often equals and hashCode in the item itself). So it is better to enforce a strict limit than have weird looking errors, where a skip limit is reached without anything being skipped.

Parameters:

skipCacheCapacity - the capacity to set

read

protected Object read(StepContribution contribution)
               throws Exception

Tries to read the item from the reader, in case of exception skip the item if the skip policy allows, otherwise re-throw.

Overrides:

read in class SimpleItemHandler

Parameters:

contribution - current StepContribution holding skipped items count

Returns:

next item for processing

Throws:

Exception

write

protected void write(Object item,
                     StepContribution contribution)
              throws Exception

Tries to write the item using the writer. In case of exception consults skip policy before re-throwing the exception. The exception is always re-thrown, but if the item is seen again on read it will be skipped.

Overrides:

write in class SimpleItemHandler

Parameters:

item - item to write

contribution - current StepContribution holding skipped items count

Throws:

Exception

doWriteWithSkip

protected final void doWriteWithSkip(Object item,
                                     StepContribution contribution)
                              throws Exception

Parameters:

item -

contribution -

Throws:

Exception

mark

public void mark()
          throws MarkFailedException

Description copied from interface: ItemHandler

Implementations should delegate to an ItemReader.

Specified by:

mark in interface ItemHandler

Overrides:

mark in class SimpleItemHandler

Throws:

MarkFailedException

See Also:

ItemReader.mark()