BATCH-1728: Added some documentation in the AbstractPaginatedDataItemReader and fixed the message in the RepositoryItemWriter

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/data/AbstractPaginatedDataItemReader.java

@@ -2,10 +2,21 @@ package org.springframework.batch.item.data;
 
 import java.util.Iterator;
 
+import org.springframework.batch.item.ItemReader;
+import org.springframework.batch.item.ItemStreamReader;
 import org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader;
 
+/**
+ * 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.
+ * 
+ * @author Michael Minella
+ * @since 2.2
+ * @param <T> Type of item to be read
+ */
 public abstract class AbstractPaginatedDataItemReader<T> extends
-		AbstractItemCountingItemStreamItemReader<T> {
+AbstractItemCountingItemStreamItemReader<T> {
 
 	protected volatile int page = 0;
 
@@ -15,6 +26,11 @@ public abstract class AbstractPaginatedDataItemReader<T> extends
 
 	private Object lock = new Object();
 
+	/**
+	 * The number of items to be read with each page.
+	 * 
+	 * @param pageSize the number of items
+	 */
 	public void setPageSize(int pageSize) {
 		this.pageSize = pageSize;
 	}
@@ -44,7 +60,19 @@ public abstract class AbstractPaginatedDataItemReader<T> extends
 		}
 	}
 
-	protected abstract Iterator doPageRead();
+	/**
+	 * Method this {@link ItemStreamReader} delegates to
+	 * for the actual work of reading a page.  Each time
+	 * this method is called, the resulting {@link Iterator}
+	 * should contain the items read within the next page.
+	 * <br/><br/>
+	 * If the {@link Iterator} is empty or null when it is
+	 * returned, this {@link ItemReader} will assume that the
+	 * input has been exhausted.
+	 * 
+	 * @return an {@link Iterator} containing the items within a page.
+	 */
+	protected abstract Iterator<T> doPageRead();
 
 	@Override
 	protected void doOpen() throws Exception {
@@ -60,7 +88,7 @@ public abstract class AbstractPaginatedDataItemReader<T> extends
 			page = itemLastIndex / pageSize;
 			int current = itemLastIndex % pageSize;
 
-			Iterator initialPage = doPageRead();
+			Iterator<T> initialPage = doPageRead();
 
 			for(; current >= 0; current--) {
 				initialPage.next();

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/data/RepositoryItemWriter.java

@@ -84,6 +84,7 @@ public class RepositoryItemWriter implements ItemWriter, InitializingBean {
 	 *
 	 * @see org.springframework.batch.item.ItemWriter#write(java.util.List)
 	 */
+	@Override
 	public void write(List items) throws Exception {
 		if(!CollectionUtils.isEmpty(items)) {
 			doWrite(items);
@@ -112,8 +113,9 @@ public class RepositoryItemWriter implements ItemWriter, InitializingBean {
 	/**
 	 * Check mandatory properties - there must be a repository.
 	 */
+	@Override
 	public void afterPropertiesSet() throws Exception {
-		Assert.state(repository != null, "A CRUDRepository is required");
+		Assert.state(repository != null, "A CrudRepository implementation is required");
 	}