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 in
AbstractPagingItemReader.setPageSize(int)
. Additional pages are requested when needed as
AbstractItemCountingItemStreamItemReader.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 use
saveState=false
if used in a multi-threaded client (no
restart available).
Since:
Author:
Thomas Risberg, Dave Syer, Michael Minella, Mahmoud Ben Hassine
Fields inherited from class org.springframework.batch.item.database.
AbstractPagingItemReader
logger
,
results
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 this
ResultSet
object.
The parameter values to be used for the query execution.
setRowMapper
(org.springframework.jdbc.core.RowMapper<
T
> rowMapper)
The row mapper implementation to be used by this reader.
Methods inherited from class org.springframework.batch.item.database.
AbstractPagingItemReader
doClose
,
doOpen
,
doRead
,
getPage
,
getPageSize
,
jumpToItem
,
setPageSize
close
,
getCurrentItemCount
,
isSaveState
,
read
,
setCurrentItemCount
,
setMaxItemCount
,
setSaveState
Methods inherited from class org.springframework.batch.item.
ItemStreamSupport
getExecutionContextKey
,
getName
,
setExecutionContextName
,
setName
Methods inherited from class java.lang.
Object
clone
,
equals
,
finalize
,
getClass
,
hashCode
,
notify
,
notifyAll
,
toString
,
wait
,
wait
,
wait
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 this
ResultSet
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
A
PagingQueryProvider
. Supplies all the platform dependent query generation
capabilities needed by the reader.
queryProvider
- the
PagingQueryProvider
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
- a
RowMapper
implementation
setParameterValues
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.
Specified by:
afterPropertiesSet
in interface
org.springframework.beans.factory.InitializingBean
Overrides:
afterPropertiesSet
in class
AbstractPagingItemReader
<
T
>
Throws:
Exception
See Also:
InitializingBean.afterPropertiesSet()
update
Specified by:
update
in interface
ItemStream
Overrides:
update
in class
AbstractItemCountingItemStreamItemReader
<
T
>
Parameters:
executionContext
- to be updated
Throws:
ItemStreamException
See Also:
ItemStream.update(ExecutionContext)
No-op.
Specified by:
open
in interface
ItemStream
Overrides:
open
in class
AbstractItemCountingItemStreamItemReader
<
T
>
Parameters:
executionContext
- current step's
ExecutionContext
. Will be the
executionContext from the last run of the step on a restart.
See Also:
ItemStream.open(ExecutionContext)
