DATACMNS-650 - Introduced CloseableIterator abstraction as a foundation for streaming of results.

A CloseableIterator abstracts the underlying result with support for releasing the associated resources via close() which can be transparently be used with TRW in Java 7 since Closeable implements AutoCloseable from Java 7 upwards.

Original pull request: #116.

Author: Thomas Darimont

src/main/java/org/springframework/data/util/CloseableIterator.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2015 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.data.util;
+
+import java.io.Closeable;
+import java.util.Iterator;
+
+/**
+ * A {@link CloseableIterator} serves as a bridging data structure for the underlying data store specific results that
+ * can be wrapped in a Java 8 {@link java.util.stream.Stream}.
+ * <p>
+ * For convenient usage in an advanced for-loop we the {@code iterator()} method should return {@literal this}.
+ * 
+ * @author Thomas Darimont
+ * @param <T>
+ * @since 1.10
+ */
+public interface CloseableIterator<T> extends Iterator<T>, Closeable, Iterable<T> {
+
+	/**
+	 * Closes this iterator, freeing any resources created.
+	 */
+	@Override
+	void close();
+
+}