Class AbstractPaginatedDataItemReader<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.data.AbstractPaginatedDataItemReader<T>
- Type Parameters:
T
- Type of item to be read
- All Implemented Interfaces:
ItemReader<T>
,ItemStream
,ItemStreamReader<T>
- Direct Known Subclasses:
MongoItemReader
,Neo4jItemReader
public abstract class AbstractPaginatedDataItemReader<T>
extends AbstractItemCountingItemStreamItemReader<T>
A base class that handles basic reading logic based on the paginated semantics of
Spring Data's paginated facilities. It also handles the semantics required for
restartability based on those facilities.
- Since:
- 2.2
- Author:
- Michael Minella, Glenn Renfro
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Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected void
doClose()
Close the resources opened inAbstractItemCountingItemStreamItemReader.doOpen()
.protected void
doOpen()
Open resources necessary to start reading input.Method thisItemStreamReader
delegates to for the actual work of reading a page.protected T
doRead()
Read next item from input.protected void
jumpToItem
(int itemLastIndex) Move to the given item index.void
setPageSize
(int pageSize) The number of items to be read with each page.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
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Field Details
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page
protected volatile int page -
pageSize
protected int pageSize -
results
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Constructor Details
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AbstractPaginatedDataItemReader
public AbstractPaginatedDataItemReader()
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Method Details
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setPageSize
public void setPageSize(int pageSize) The number of items to be read with each page.- Parameters:
pageSize
- the number of items. pageSize must be greater than zero.
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doRead
Description copied from class:AbstractItemCountingItemStreamItemReader
Read next item from input.- Specified by:
doRead
in classAbstractItemCountingItemStreamItemReader<T>
- Returns:
- an item or
null
if the data source is exhausted - Throws:
Exception
- Allows subclasses to throw checked exceptions for interpretation by the framework
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doPageRead
Method thisItemStreamReader
delegates to for the actual work of reading a page. Each time this method is called, the resultingIterator
should contain the items read within the next page.
If theIterator
is empty or null when it is returned, thisItemReader
will assume that the input has been exhausted.- Returns:
- an
Iterator
containing the items within a page.
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doOpen
Description copied from class:AbstractItemCountingItemStreamItemReader
Open resources necessary to start reading input.- Specified by:
doOpen
in classAbstractItemCountingItemStreamItemReader<T>
- Throws:
Exception
- Allows subclasses to throw checked exceptions for interpretation by the framework
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doClose
Description copied from class:AbstractItemCountingItemStreamItemReader
Close the resources opened inAbstractItemCountingItemStreamItemReader.doOpen()
.- Specified by:
doClose
in classAbstractItemCountingItemStreamItemReader<T>
- Throws:
Exception
- Allows subclasses to throw checked exceptions for interpretation by the framework
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jumpToItem
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 usingAbstractItemCountingItemStreamItemReader.doRead()
.- Overrides:
jumpToItem
in classAbstractItemCountingItemStreamItemReader<T>
- Parameters:
itemLastIndex
- index of item (0 based) to jump to.- Throws:
Exception
- Allows subclasses to throw checked exceptions for interpretation by the framework
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