Adds builder for SingleItemPeekableItemReader

resolves BATCH-2593

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/support/builder/SingleItemPeekableItemReaderBuilder.java

@@ -0,0 +1,61 @@
+/*
+ * 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.support.builder;
+
+import org.springframework.batch.item.ItemReader;
+import org.springframework.batch.item.support.SingleItemPeekableItemReader;
+import org.springframework.util.Assert;
+
+/**
+ * Creates a fully qualified SingleItemPeekeableItemReader.
+ *
+ * @author Glenn Renfro
+ *
+ * @since 4.0
+ */
+public class SingleItemPeekableItemReaderBuilder<T> {
+
+	private ItemReader<T> delegate;
+
+	/**
+	 * The item reader to use as a delegate. Items are read from the delegate and passed
+	 * to the caller in
+	 * {@link org.springframework.batch.item.support.SingleItemPeekableItemReader#read()}.
+	 *
+	 * @param delegate the delegate to set
+	 * @return this instance for method chaining
+	 * @see SingleItemPeekableItemReader#setDelegate(ItemReader)
+	 */
+	public SingleItemPeekableItemReaderBuilder<T> delegate(ItemReader<T> delegate) {
+		this.delegate = delegate;
+
+		return this;
+	}
+
+	/**
+	 * Returns a fully constructed {@link SingleItemPeekableItemReader}.
+	 *
+	 * @return a new {@link SingleItemPeekableItemReader}
+	 */
+	public SingleItemPeekableItemReader<T> build() {
+		Assert.notNull(this.delegate, "A delegate is required");
+
+		SingleItemPeekableItemReader<T> reader = new SingleItemPeekableItemReader<>();
+		reader.setDelegate(this.delegate);
+		return reader;
+	}
+}