Create a builder for the JpaPagingItemReader

This commit adds a builder for the JpaPagingItemReader

Resolves BATCH-2591

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

@@ -36,7 +36,7 @@ import org.springframework.util.MethodInvoker;
  * </p>
  *
  * <p>
- * It depends on {@link org.springframework.data.repository.CrudRepository#save(Iterable)}
+ * It depends on {@link org.springframework.data.repository.CrudRepository#saveAll(Iterable)}
  * method to store the items for the chunk.  Performance will be determined by that
  * implementation more than this writer.
  * </p>

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/database/builder/HibernatePagingItemReaderBuilder.java

@@ -84,7 +84,6 @@ public class HibernatePagingItemReaderBuilder<T> {
 	 * @return this instance for method chaining
 	 * @see HibernatePagingItemReader#setCurrentItemCount(int)
 	 */
-
 	public HibernatePagingItemReaderBuilder<T> currentItem(int currentItem) {
 		this.currentItem = currentItem;
 

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/database/builder/JpaPagingItemReaderBuilder.java

@@ -0,0 +1,221 @@
+/*
+ * Copyright 2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.batch.item.database.builder;
+
+import java.util.Map;
+import javax.persistence.EntityManagerFactory;
+
+import org.springframework.batch.item.database.JpaPagingItemReader;
+import org.springframework.batch.item.database.orm.JpaQueryProvider;
+import org.springframework.util.Assert;
+
+/**
+ * @author Michael Minella
+ */
+public class JpaPagingItemReaderBuilder<T> {
+
+	private String name;
+
+	private int currentItem = 0;
+
+	private int maxItemCount = Integer.MAX_VALUE;
+
+	private boolean saveState = true;
+
+	private int pageSize = 10;
+
+	private EntityManagerFactory entityManagerFactory;
+
+	private Map<String, Object> parameterValues;
+
+	private boolean transacted = true;
+
+	private String queryString;
+
+	private JpaQueryProvider queryProvider;
+
+	/**
+	 * A name used to prevent key collisions while saving the state in the
+	 * {@link org.springframework.batch.item.ExecutionContext}
+	 *
+	 * @param name unique name for this reader instance
+	 * @return this instance for method chaining
+	 * @see JpaPagingItemReader#setName(String)
+	 */
+	public JpaPagingItemReaderBuilder<T> name(String name) {
+		this.name = name;
+
+		return this;
+	}
+
+	/**
+	 * Index for the current item.  Used on restarts to indicate where to start from.
+	 *
+	 * @param currentItem current index
+	 * @return this instance for method chaining
+	 * @see JpaPagingItemReader#setCurrentItemCount(int)
+	 */
+	public JpaPagingItemReaderBuilder<T> currentItem(int currentItem) {
+		this.currentItem = currentItem;
+
+		return this;
+	}
+
+	/**
+	 * The index of the max item to be read.
+	 *
+	 * @param maxItemCount max index
+	 * @return this instance for method chaining
+	 * @see JpaPagingItemReader#setMaxItemCount(int)
+	 */
+	public JpaPagingItemReaderBuilder<T> maxItemCount(int maxItemCount) {
+		this.maxItemCount = maxItemCount;
+
+		return this;
+	}
+
+	/**
+	 * Indicates if the state should be saved.  If set to false, restarts will begin at
+	 * the beginning of the dataset.  Defaults to true
+	 *
+	 * @param saveState indicator
+	 * @return this instance for method chaining
+	 * @see JpaPagingItemReader#setSaveState(boolean)
+	 */
+	public JpaPagingItemReaderBuilder<T> saveState(boolean saveState) {
+		this.saveState = saveState;
+
+		return this;
+	}
+
+	/**
+	 * The number of records to request per page/query.  Defaults to 10.  Must be greater
+	 * than zero.
+	 *
+	 * @param pageSize number of items
+	 * @return this instance for method chaining
+	 * @see JpaPagingItemReader#setPageSize(int)
+	 */
+	public JpaPagingItemReaderBuilder<T> pageSize(int pageSize) {
+		this.pageSize = pageSize;
+
+		return this;
+	}
+
+	/**
+	 * A map of parameter values to be set on the query.   The key of the map is the name
+	 * of the parameter to be set with the value being the value to be set.
+	 *
+	 * @param parameterValues map of values
+	 * @return this instance for method chaining
+	 * @see JpaPagingItemReader#setParameterValues(Map)
+	 */
+	public JpaPagingItemReaderBuilder<T> parameterValues(Map<String, Object> parameterValues) {
+		this.parameterValues = parameterValues;
+
+		return this;
+	}
+
+	/**
+	 * A query provider.  This should be set only if {@link #queryString(String)} have not
+	 * been set.
+	 *
+	 * @param queryProvider the query provider
+	 * @return this instance for method chaining
+	 * @see JpaPagingItemReader#setQueryProvider(JpaQueryProvider)
+	 */
+	public JpaPagingItemReaderBuilder<T> queryProvider(JpaQueryProvider queryProvider) {
+		this.queryProvider = queryProvider;
+
+		return this;
+	}
+
+	/**
+	 * The HQL query string to execute.  This should only be set if
+	 * {@link #queryProvider(JpaQueryProvider)} has not been set.
+	 *
+	 * @param queryString the HQL query
+	 * @return this instance for method chaining
+	 * @see JpaPagingItemReader#setQueryString(String)
+	 */
+	public JpaPagingItemReaderBuilder<T> queryString(String queryString) {
+		this.queryString = queryString;
+
+		return this;
+	}
+
+	/**
+	 * Indicates if a transaction should be created around the read (true by default).
+	 * Can be set to false in cases where JPA implementation doesn't support a particular
+	 * transaction, however this may cause object inconsistency in the EntityManagerFactory.
+	 *
+	 * @param transacted defaults to true
+	 * @return this instance for method chaining
+	 * @see JpaPagingItemReader#setTransacted(boolean)
+	 */
+	public JpaPagingItemReaderBuilder<T> transacted(boolean transacted) {
+		this.transacted = transacted;
+
+		return this;
+	}
+
+	/**
+	 * The {@link EntityManagerFactory} to be used for executing the configured
+	 * {@link #queryString}.
+	 *
+	 * @param entityManagerFactory
+	 * @return
+	 */
+	public JpaPagingItemReaderBuilder<T> entityManagerFactory(EntityManagerFactory entityManagerFactory) {
+		this.entityManagerFactory = entityManagerFactory;
+
+		return this;
+	}
+
+	/**
+	 * Returns a fully constructed {@link JpaPagingItemReader}.
+	 *
+	 * @return a new {@link JpaPagingItemReader}
+	 */
+	public JpaPagingItemReader<T> build() {
+		Assert.isTrue(this.pageSize > 0, "pageSize must be greater than zero");
+		Assert.notNull(this.entityManagerFactory, "An EntityManagerFactory is required");
+
+		if(this.saveState) {
+			Assert.hasText(this.name,
+					"A name is required when saveState is set to true");
+		}
+
+		if(this.queryProvider == null) {
+			Assert.hasLength(this.queryString, "Query string is required when queryProvider is null");
+		}
+
+		JpaPagingItemReader<T> reader = new JpaPagingItemReader<>();
+
+		reader.setQueryString(this.queryString);
+		reader.setPageSize(this.pageSize);
+		reader.setParameterValues(this.parameterValues);
+		reader.setEntityManagerFactory(this.entityManagerFactory);
+		reader.setQueryProvider(this.queryProvider);
+		reader.setTransacted(this.transacted);
+		reader.setCurrentItemCount(this.currentItem);
+		reader.setMaxItemCount(this.maxItemCount);
+		reader.setSaveState(this.saveState);
+		reader.setName(this.name);
+
+		return reader;
+	}
+}