org.springframework.batch.item
Interface ItemReader<T>
- All Known Subinterfaces:
- ItemStreamReader<T>, ResourceAwareItemReaderItemStream<T>
- All Known Implementing Classes:
- AbstractItemCountingItemStreamItemReader, AbstractItemStreamItemReader, AbstractPagingItemReader, AggregateItemReader, ExampleItemReader, ExceptionThrowingItemReaderProxy, FlatFileItemReader, GeneratingTradeItemReader, HibernateCursorItemReader, IbatisPagingItemReader, InfiniteLoopReader, ItemReaderAdapter, JdbcCursorItemReader, JdbcPagingItemReader, JmsItemReader, JpaPagingItemReader, ListItemReader, MultiResourceItemReader, OrderItemReader, StagingItemReader, StaxEventItemReader
public interface ItemReader<T>
Strategy interface for providing the data.
Implementations are expected to be stateful and will be called multiple times
for each batch, with each call to read()
returning a different value
and finally returning null
when all input data is
exhausted.
Implementations need *not* be thread safe and clients of a ItemReader
need to be aware that this is the case.
A richer interface (e.g. with a look ahead or peek) is not feasible because
we need to support transactions in an asynchronous batch.
- Since:
- 1.0
- Author:
- Rob Harrop, Dave Syer, Lucas Ward
Method Summary |
T |
read()
Reads a piece of input data and advance to the next one. |
read
T read()
throws Exception,
UnexpectedInputException,
ParseException
- Reads a piece of input data and advance to the next one. Implementations
must return
null
at the end of the input
data set. In a transactional setting, caller might get the same item
twice from successive calls (or otherwise), if the first call was in a
transaction that rolled back.
- Throws:
Exception
- if an underlying resource is unavailable.
UnexpectedInputException
ParseException
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