Class JdbcPagingItemReader<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.JdbcPagingItemReader<T>
- All Implemented Interfaces:
ItemReader<T>
,ItemStream
,ItemStreamReader<T>
,org.springframework.beans.factory.InitializingBean
public class JdbcPagingItemReader<T> extends AbstractPagingItemReader<T> implements org.springframework.beans.factory.InitializingBean
ItemReader
for reading database records using JDBC in a paging fashion.It executes the SQL built by the
PagingQueryProvider
to retrieve requested data. The query is executed using paged requests of a size specified inAbstractPagingItemReader.setPageSize(int)
. Additional pages are requested when needed asAbstractItemCountingItemStreamItemReader.read()
method is called, returning an object corresponding to current position. On restart it uses the last sort key value to locate the first page to read (so it doesn't matter if the successfully processed items have been removed or modified). It is important to have a unique key constraint on the sort key to guarantee that no data is lost between executions.The performance of the paging depends on the database specific features available to limit the number of returned rows. 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
open(ExecutionContext)
, but remember to usesaveState=false
if used in a multi-threaded client (no restart available).- Since:
- 2.0
- Author:
- Thomas Risberg, Dave Syer, Michael Minella, Mahmoud Ben Hassine
Field Summary
Fields Modifier and Type Field Description static int
VALUE_NOT_SET
Fields inherited from class org.springframework.batch.item.database.AbstractPagingItemReader
logger, results
Constructor Summary
Constructors Constructor Description JdbcPagingItemReader()
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
afterPropertiesSet()
Check mandatory properties.protected void
doJumpToPage(int itemIndex)
protected void
doReadPage()
void
open(ExecutionContext executionContext)
No-op.void
setDataSource(javax.sql.DataSource dataSource)
void
setFetchSize(int fetchSize)
Gives the JDBC driver a hint as to the number of rows that should be fetched from the database when more rows are needed for thisResultSet
object.void
setParameterValues(java.util.Map<java.lang.String,java.lang.Object> parameterValues)
The parameter values to be used for the query execution.void
setQueryProvider(PagingQueryProvider queryProvider)
void
setRowMapper(org.springframework.jdbc.core.RowMapper<T> rowMapper)
The row mapper implementation to be used by this reader.void
update(ExecutionContext executionContext)
Return emptyExecutionContext
.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, read, setCurrentItemCount, setMaxItemCount, setSaveState
Methods inherited from class org.springframework.batch.item.ItemStreamSupport
getExecutionContextKey, setExecutionContextName, setName
Field Detail
VALUE_NOT_SET
public static final int VALUE_NOT_SET
- See Also:
- Constant Field Values
Method Detail
setDataSource
public void setDataSource(javax.sql.DataSource dataSource)
setFetchSize
public void setFetchSize(int fetchSize)
Gives the JDBC driver a hint as to the number of rows that should be fetched from the database when more rows are needed for thisResultSet
object. If the fetch size specified is zero, the JDBC driver ignores the value.- Parameters:
fetchSize
- the number of rows to fetch- See Also:
ResultSet.setFetchSize(int)
setQueryProvider
public void setQueryProvider(PagingQueryProvider queryProvider)
APagingQueryProvider
. Supplies all the platform dependent query generation capabilities needed by the reader.- Parameters:
queryProvider
- thePagingQueryProvider
to use
setRowMapper
public void setRowMapper(org.springframework.jdbc.core.RowMapper<T> rowMapper)
The row mapper implementation to be used by this reader. The row mapper is used to convert result set rows into objects, which are then returned by the reader.- Parameters:
rowMapper
- aRowMapper
implementation
setParameterValues
public void setParameterValues(java.util.Map<java.lang.String,java.lang.Object> parameterValues)
The parameter values to be used for the query execution. If you use named parameters then the key should be the name used in the query clause. If you use "?" placeholders then the key should be the relative index that the parameter appears in the query string built using the select, from and where clauses specified.- Parameters:
parameterValues
- the values keyed by the parameter named/index used in the query string.
afterPropertiesSet
public void afterPropertiesSet() throws java.lang.Exception
Check mandatory properties.- Specified by:
afterPropertiesSet
in interfaceorg.springframework.beans.factory.InitializingBean
- Overrides:
afterPropertiesSet
in classAbstractPagingItemReader<T>
- Throws:
java.lang.Exception
- See Also:
InitializingBean.afterPropertiesSet()
doReadPage
protected void doReadPage()
- Specified by:
doReadPage
in classAbstractPagingItemReader<T>
update
public void update(ExecutionContext executionContext) throws ItemStreamException
Description copied from class:ItemStreamSupport
Return emptyExecutionContext
.- Specified by:
update
in interfaceItemStream
- Overrides:
update
in classAbstractItemCountingItemStreamItemReader<T>
- Parameters:
executionContext
- to be updated- Throws:
ItemStreamException
- See Also:
ItemStream.update(ExecutionContext)
open
public void open(ExecutionContext executionContext)
Description copied from class:ItemStreamSupport
No-op.- Specified by:
open
in interfaceItemStream
- Overrides:
open
in classAbstractItemCountingItemStreamItemReader<T>
- Parameters:
executionContext
- current step'sExecutionContext
. Will be the executionContext from the last run of the step on a restart.- See Also:
ItemStream.open(ExecutionContext)
doJumpToPage
protected void doJumpToPage(int itemIndex)
- Specified by:
doJumpToPage
in classAbstractPagingItemReader<T>