1313 * See the License for the specific language governing permissions and
1414 * limitations under the License.
1515 */
16- 1716package org .springframework .batch .item ;
1817
18+ import java .util .function .Function ;
19+ 1920import org .springframework .lang .NonNull ;
2021
2122/**
3738 * @author Lucas Ward
3839 * @author Taeik Lim
3940 * @author Mahmoud Ben Hassine
41+ * @author Stefano Cordio
4042 */
4143@ FunctionalInterface
4244public interface ItemWriter <T > {
@@ -50,4 +52,27 @@ public interface ItemWriter<T> {
5052 */
5153 void write (@ NonNull Chunk <? extends T > chunk ) throws Exception ;
5254
55+ /**
56+ * Adapts an {@code ItemWriter} accepting items of type {@link U} to one accepting
57+ * items of type {@link T} by applying a mapping function to each item before writing.
58+ * <p>
59+ * The {@code mapping()} item writers are most useful when used in combination with a
60+ * {@link org.springframework.batch.item.support.CompositeItemWriter}, where the
61+ * mapping function in front of the downstream writer can be a getter of the input
62+ * item or a more complex transformation logic.
63+ * <p>
64+ * This adapter mimics the behavior of
65+ * {@link java.util.stream.Collectors#mapping(Function, java.util.stream.Collector)}.
66+ * @param <T> the type of the input items
67+ * @param <U> type of items accepted by downstream item writer
68+ * @param mapper a function to be applied to the input items
69+ * @param downstream an item writer which will accept mapped items
70+ * @return an item writer which applies the mapping function to the input items and
71+ * provides the mapped results to the downstream item writer
72+ * @since 6.0
73+ */
74+ static <T , U > ItemWriter <T > mapping (Function <? super T , ? extends U > mapper , ItemWriter <? super U > downstream ) {
75+ return chunk -> downstream .write (new Chunk <>(chunk .getItems ().stream ().map (mapper ).toList ()));
76+ }
77+ 5378}
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