org.springframework.batch.item.database
Class AbstractPagingItemReader<T>

java.lang.Object
  org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader<T>
      org.springframework.batch.item.database.AbstractPagingItemReader<T>

All Implemented Interfaces:

ItemReader<T>, ItemStream, InitializingBean

Direct Known Subclasses:

IbatisPagingItemReader, JdbcPagingItemReader, JpaPagingItemReader

public abstract class AbstractPagingItemReader<T>
extends AbstractItemCountingItemStreamItemReader<T>
implements InitializingBean

Abstract ItemReader for to extend when reading database records in a paging fashion. Implementations should execute queries using paged requests of a size specified in setPageSize(int). Additional pages are requested when needed as AbstractItemCountingItemStreamItemReader.read() method is called, returning an object corresponding to current position.

Since:

2.0

Author:

Thomas Risberg

Field Summary

protected int	current
protected boolean	initialized
protected Log	logger
protected int	page
protected int	pageSize
protected List<T>	results

Constructor Summary

AbstractPagingItemReader()

Method Summary

void	afterPropertiesSet() Check mandatory properties.
protected void	doClose() Close the resources opened in AbstractItemCountingItemStreamItemReader.doOpen().
protected abstract void	doJumpToPage(int itemIndex)
protected void	doOpen() Open resources necessary to start reading input.
protected T	doRead() Read next item from input.
protected abstract void	doReadPage()
protected void	jumpToItem(int itemIndex) Move to the given item index.
void	setPageSize(int pageSize) The number of rows to retreive at a time.

Methods inherited from class org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader

close, getCurrentItemCount, open, read, setCurrentItemCount, setMaxItemCount, setName, setSaveState, update

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected Log logger

initialized

protected boolean initialized

current

protected int current

page

protected int page

pageSize

protected int pageSize

results

protected List<T> results

Constructor Detail

AbstractPagingItemReader

public AbstractPagingItemReader()

Method Detail

setPageSize

public void setPageSize(int pageSize)

The number of rows to retreive at a time.

Parameters:

pageSize - the number of rows to fetch per page

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Check mandatory properties.

Specified by:

afterPropertiesSet in interface InitializingBean

Throws:

Exception

See Also:

InitializingBean.afterPropertiesSet()

doRead

protected T doRead()
            throws Exception

Description copied from class: AbstractItemCountingItemStreamItemReader

Read next item from input.

Specified by:

doRead in class AbstractItemCountingItemStreamItemReader<T>

Returns:

item

Throws:

Exception

doReadPage

protected abstract void doReadPage()

doOpen

protected void doOpen()
               throws Exception

Description copied from class: AbstractItemCountingItemStreamItemReader

Open resources necessary to start reading input.

Specified by:

doOpen in class AbstractItemCountingItemStreamItemReader<T>

Throws:

Exception

doClose

protected void doClose()
                throws Exception

Description copied from class: AbstractItemCountingItemStreamItemReader

Close the resources opened in AbstractItemCountingItemStreamItemReader.doOpen().

Specified by:

doClose in class AbstractItemCountingItemStreamItemReader<T>

Throws:

Exception

jumpToItem

protected void jumpToItem(int itemIndex)
                   throws Exception

Description copied from class: AbstractItemCountingItemStreamItemReader

Move to the given item index. Subclasses should override this method if there is a more efficient way of moving to given index than re-reading the input using AbstractItemCountingItemStreamItemReader.doRead().

Overrides:

jumpToItem in class AbstractItemCountingItemStreamItemReader<T>

Throws:

Exception

doJumpToPage

protected abstract void doJumpToPage(int itemIndex)