ItemWriter
ItemWriter is similar in functionality to an ItemReader but with inverse operations.
Resources still need to be located, opened, and closed but they differ in that an
ItemWriter writes out, rather than reading in. In the case of databases or queues,
these operations may be inserts, updates, or sends. The format of the serialization of
the output is specific to each batch job.
As with ItemReader,
ItemWriter is a fairly generic interface, as shown in the following interface definition:
public interface ItemWriter<T> {
void write(Chunk<? extends T> items) throws Exception;
}As with read on ItemReader, write provides the basic contract of ItemWriter. It
attempts to write out the list of items passed in as long as it is open. Because it is
generally expected that items are 'batched' together into a chunk and then output, the
interface accepts a list of items, rather than an item by itself. After writing out the
list, any flushing that may be necessary can be performed before returning from the write
method. For example, if writing to a Hibernate DAO, multiple calls to write can be made,
one for each item. The writer can then call flush on the hibernate session before
returning.