org.springframework.batch.item.database

Class IbatisPagingItemReader<T>

java.lang.Object

org.springframework.batch.item.ItemStreamSupport

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

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

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

org.springframework.batch.item.database.IbatisPagingItemReader<T>

All Implemented Interfaces:

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

public class IbatisPagingItemReader<T>
extends AbstractPagingItemReader<T>

ItemReader for reading database records using iBATIS in a paging fashion.

It executes the query specified as the setQueryId(String) to retrieve requested data. The query is executed using paged requests of a size specified in AbstractPagingItemReader.setPageSize(int). Additional pages are requested when needed as AbstractItemCountingItemStreamItemReader.read() method is called, returning an object corresponding to current position. Some standard query parameters are provided by the reader and the SQL in the named query must use some or all of these parameters (depending on the SQL variant) to construct a result set of the required size. The parameters are:

• _page: the page number to be read (starting at 0)
• _pagesize: the size of the pages, i.e. the number of rows to return
• _skiprows: the product of _page and _pagesize

Failure to write the correct platform-specific SQL often results in an infinite loop in the reader because it keeps asking for the next page and gets the same result set over and over.

The performance of the paging depends on the iBATIS implementation. Setting a fairly large page size and using a commit interval that matches the page size should provide better performance.

The implementation is thread-safe in between calls to AbstractItemCountingItemStreamItemReader.open(ExecutionContext), but remember to use saveState=false if used in a multi-threaded client (no restart available).

Since:

2.0

Author:

Thomas Risberg, Dave Syer

Field Summary

Fields inherited from class org.springframework.batch.item.database.AbstractPagingItemReader

logger, results

Constructor Summary

Constructors

Constructor and Description
IbatisPagingItemReader()

Method Summary

Methods

Modifier and Type	Method and Description
void	afterPropertiesSet() Check mandatory properties.
protected void	doJumpToPage(int itemIndex)
protected void	doReadPage()
void	setParameterValues(Map<String,Object> parameterValues) The parameter values to be used for the query execution.
void	setQueryId(String queryId)
void	setSqlMapClient(com.ibatis.sqlmap.client.SqlMapClient sqlMapClient)

Methods inherited from class org.springframework.batch.item.database.AbstractPagingItemReader

doClose, doOpen, doRead, getPage, getPageSize, jumpToItem, setPageSize

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

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

Methods inherited from class org.springframework.batch.item.ItemStreamSupport

getExecutionContextKey, setExecutionContextName, setName

Methods inherited from class java.lang.Object

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

Constructor Detail

IbatisPagingItemReader

public IbatisPagingItemReader()

Method Detail

setSqlMapClient

public void setSqlMapClient(com.ibatis.sqlmap.client.SqlMapClient sqlMapClient)

setQueryId

public void setQueryId(String queryId)

setParameterValues

public void setParameterValues(Map<String,Object> parameterValues)

The parameter values to be used for the query execution.

Parameters:

parameterValues - the values keyed by the parameter named used in the query string.

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Check mandatory properties.

Specified by:

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

Overrides:

afterPropertiesSet in class AbstractPagingItemReader<T>

Throws:

Exception

See Also:

InitializingBean.afterPropertiesSet()

doReadPage

protected void doReadPage()

Specified by:

doReadPage in class AbstractPagingItemReader<T>

doJumpToPage

protected void doJumpToPage(int itemIndex)

Specified by:

doJumpToPage in class AbstractPagingItemReader<T>