Add builder for AmqpItemReader

resolves BATCH-2615

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/amqp/AmqpItemReader.java

@@ -33,6 +33,11 @@ public class AmqpItemReader<T> implements ItemReader<T> {
 	private final AmqpTemplate amqpTemplate;
 	private Class<? extends T> itemType;
 
+	/**
+	 * Initialize the AmqpItemReader.
+	 *
+	 * @param amqpTemplate the template to be used.  Must not be null.
+	 */
 	public AmqpItemReader(final AmqpTemplate amqpTemplate) {
 		Assert.notNull(amqpTemplate, "AmpqTemplate must not be null");
 
@@ -56,6 +61,11 @@ public class AmqpItemReader<T> implements ItemReader<T> {
 		return (T) result;
 	}
 
+	/**
+	 * Establish the itemType for the reader.
+	 * 
+	 * @param itemType class type that will be returned by the reader.
+	 */
 	public void setItemType(Class<? extends T> itemType) {
 		Assert.notNull(itemType, "Item type cannot be null");
 		this.itemType = itemType;

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/amqp/builder/AmqpItemReaderBuilder.java

@@ -0,0 +1,75 @@
+/*
+ * 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.amqp.builder;
+
+import org.springframework.amqp.core.AmqpTemplate;
+import org.springframework.batch.item.amqp.AmqpItemReader;
+import org.springframework.util.Assert;
+
+/**
+ * A builder implementation for the {@link AmqpItemReader}
+ *
+ * @author Glenn Renfro
+ * @since 4.0
+ * @see AmqpItemReader
+ */
+public class AmqpItemReaderBuilder<T> {
+
+	private AmqpTemplate amqpTemplate;
+
+	private Class<? extends T> itemType;
+
+	/**
+	 * Establish the amqpTemplate to be used by the AmqpItemReader.
+	 * @param amqpTemplate the template to be used.
+	 * @return this instance for method chaining
+	 * @see AmqpItemReader#AmqpItemReader(AmqpTemplate)
+	 */
+	public AmqpItemReaderBuilder<T> amqpTemplate(AmqpTemplate amqpTemplate) {
+		this.amqpTemplate = amqpTemplate;
+
+		return this;
+	}
+
+	/**
+	 * Establish the itemType for the reader.
+	 * @param itemType class type that will be returned by the reader.
+	 * @return this instance for method chaining.
+	 * @see AmqpItemReader#setItemType(Class)
+	 */
+	public AmqpItemReaderBuilder<T> itemType(Class<? extends T> itemType) {
+		this.itemType = itemType;
+
+		return this;
+	}
+
+	/**
+	 * Validates and builds a {@link AmqpItemReader}.
+	 *
+	 * @return a {@link AmqpItemReader}
+	 */
+	public AmqpItemReader<T> build() {
+		Assert.notNull(this.amqpTemplate, "amqpTemplate is required.");
+
+		AmqpItemReader<T> reader = new AmqpItemReader<>(this.amqpTemplate);
+		if(this.itemType != null) {
+			reader.setItemType(this.itemType);
+		}
+
+		return reader;
+	}
+}