Consistent Iterator/Stream support in PropertySources and PropertyValues

Issue: SPR-16894

Author: jhoeller

spring-beans/src/main/java/org/springframework/beans/MutablePropertyValues.java

@@ -18,16 +18,21 @@
 
 import java.io.Serializable;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.Spliterator;
+import java.util.Spliterators;
+import java.util.stream.Stream;
 
 import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
- * Default implementation of the {@link PropertyValues} interface.
+ * The default implementation of the {@link PropertyValues} interface.
  * Allows simple manipulation of properties, and provides constructors
  * to support deep copy and construction from a Map.
  *
@@ -244,6 +249,21 @@ public void removePropertyValue(String propertyName) {
 	}
 
 
+	@Override
+	public Iterator<PropertyValue> iterator() {
+		return Collections.unmodifiableList(this.propertyValueList).iterator();
+	}
+
+	@Override
+	public Spliterator<PropertyValue> spliterator() {
+		return Spliterators.spliterator(this.propertyValueList, 0);
+	}
+
+	@Override
+	public Stream<PropertyValue> stream() {
+		return this.propertyValueList.stream();
+	}
+
 	@Override
 	public PropertyValue[] getPropertyValues() {
 		return this.propertyValueList.toArray(new PropertyValue[0]);

spring-beans/src/main/java/org/springframework/beans/PropertyValues.java

@@ -16,6 +16,13 @@
 
 package org.springframework.beans;
 
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.Spliterator;
+import java.util.Spliterators;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
 import org.springframework.lang.Nullable;
 
 /**
@@ -27,7 +34,33 @@
  * @since 13 May 2001
  * @see PropertyValue
  */
-public interface PropertyValues {
+public interface PropertyValues extends Iterable<PropertyValue> {
+
+	/**
+	 * Return an {@link Iterator} over the property values.
+	 * @since 5.1
+	 */
+	@Override
+	default Iterator<PropertyValue> iterator() {
+		return Arrays.asList(getPropertyValues()).iterator();
+	}
+
+	/**
+	 * Return a {@link Spliterator} over the property values.
+	 * @since 5.1
+	 */
+	@Override
+	default Spliterator<PropertyValue> spliterator() {
+		return Spliterators.spliterator(getPropertyValues(), 0);
+	}
+
+	/**
+	 * Return a sequential {@link Stream} containing the property values.
+	 * @since 5.1
+	 */
+	default Stream<PropertyValue> stream() {
+		return StreamSupport.stream(spliterator(), false);
+	}
 
 	/**
 	 * Return an array of the PropertyValue objects held in this object.

spring-beans/src/test/java/org/springframework/beans/AbstractPropertyValuesTests.java

@@ -30,7 +30,7 @@ public abstract class AbstractPropertyValuesTests {
 	/**
 	 * Must contain: forname=Tony surname=Blair age=50
 	 */
-	protected void doTestTony(PropertyValues pvs) throws Exception {
+	protected void doTestTony(PropertyValues pvs) {
 		assertTrue("Contains 3", pvs.getPropertyValues().length == 3);
 		assertTrue("Contains forname", pvs.contains("forname"));
 		assertTrue("Contains surname", pvs.contains("surname"));

spring-beans/src/test/java/org/springframework/beans/MutablePropertyValuesTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -16,20 +16,24 @@
 
 package org.springframework.beans;
 
+import java.util.Iterator;
+
 import org.junit.Test;
 
+import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
 
 /**
  * Tests for {@link MutablePropertyValues}.
  *
  * @author Rod Johnson
  * @author Chris Beams
+ * @author Juergen Hoeller
  */
 public class MutablePropertyValuesTests extends AbstractPropertyValuesTests {
 
 	@Test
-	public void testValid() throws Exception {
+	public void testValid() {
 		MutablePropertyValues pvs = new MutablePropertyValues();
 		pvs.addPropertyValue(new PropertyValue("forname", "Tony"));
 		pvs.addPropertyValue(new PropertyValue("surname", "Blair"));
@@ -44,7 +48,7 @@ public void testValid() throws Exception {
 	}
 
 	@Test
-	public void testAddOrOverride() throws Exception {
+	public void testAddOrOverride() {
 		MutablePropertyValues pvs = new MutablePropertyValues();
 		pvs.addPropertyValue(new PropertyValue("forname", "Tony"));
 		pvs.addPropertyValue(new PropertyValue("surname", "Blair"));
@@ -59,7 +63,7 @@ public void testAddOrOverride() throws Exception {
 	}
 
 	@Test
-	public void testChangesOnEquals() throws Exception {
+	public void testChangesOnEquals() {
 		MutablePropertyValues pvs = new MutablePropertyValues();
 		pvs.addPropertyValue(new PropertyValue("forname", "Tony"));
 		pvs.addPropertyValue(new PropertyValue("surname", "Blair"));
@@ -70,7 +74,7 @@ public void testChangesOnEquals() throws Exception {
 	}
 
 	@Test
-	public void testChangeOfOneField() throws Exception {
+	public void testChangeOfOneField() {
 		MutablePropertyValues pvs = new MutablePropertyValues();
 		pvs.addPropertyValue(new PropertyValue("forname", "Tony"));
 		pvs.addPropertyValue(new PropertyValue("surname", "Blair"));
@@ -103,4 +107,50 @@ public void testChangeOfOneField() throws Exception {
 		assertTrue("new value is bar", fn.getValue().equals("bar"));
 	}
 
+	@Test
+	public void iteratorContainsPropertyValue() {
+		MutablePropertyValues pvs = new MutablePropertyValues();
+		pvs.add("foo", "bar");
+
+		Iterator<PropertyValue> it = pvs.iterator();
+		assertTrue(it.hasNext());
+		PropertyValue pv = it.next();
+		assertEquals("foo", pv.getName());
+		assertEquals("bar", pv.getValue());
+
+		try {
+			it.remove();
+			fail("Should have thrown UnsupportedOperationException");
+		}
+		catch (UnsupportedOperationException ex) {
+			// expected
+		}
+		assertFalse(it.hasNext());
+	}
+
+	@Test
+	public void iteratorIsEmptyForEmptyValues() {
+		MutablePropertyValues pvs = new MutablePropertyValues();
+		Iterator<PropertyValue> it = pvs.iterator();
+		assertFalse(it.hasNext());
+	}
+
+	@Test
+	public void streamContainsPropertyValue() {
+		MutablePropertyValues pvs = new MutablePropertyValues();
+		pvs.add("foo", "bar");
+
+		assertThat(pvs.stream(), notNullValue());
+		assertThat(pvs.stream().count(), is(1L));
+		assertThat(pvs.stream().anyMatch(pv -> "foo".equals(pv.getName()) && "bar".equals(pv.getValue())), is(true));
+		assertThat(pvs.stream().anyMatch(pv -> "bar".equals(pv.getName()) && "foo".equals(pv.getValue())), is(false));
+	}
+
+	@Test
+	public void streamIsEmptyForEmptyValues() {
+		MutablePropertyValues pvs = new MutablePropertyValues();
+		assertThat(pvs.stream(), notNullValue());
+		assertThat(pvs.stream().count(), is(0L));
+	}
+
 }

spring-core/src/main/java/org/springframework/core/env/MutablePropertySources.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -18,15 +18,18 @@
 
 import java.util.Iterator;
 import java.util.List;
+import java.util.Spliterator;
+import java.util.Spliterators;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.stream.Stream;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.lang.Nullable;
 
 /**
- * Default implementation of the {@link PropertySources} interface.
+ * The default implementation of the {@link PropertySources} interface.
  * Allows manipulation of contained property sources and provides a constructor
  * for copying an existing {@code PropertySources} instance.
  *
@@ -73,6 +76,21 @@ public MutablePropertySources(PropertySources propertySources) {
 	}
 
 
+	@Override
+	public Iterator<PropertySource<?>> iterator() {
+		return this.propertySourceList.iterator();
+	}
+
+	@Override
+	public Spliterator<PropertySource<?>> spliterator() {
+		return Spliterators.spliterator(this.propertySourceList, 0);
+	}
+
+	@Override
+	public Stream<PropertySource<?>> stream() {
+		return this.propertySourceList.stream();
+	}
+
 	@Override
 	public boolean contains(String name) {
 		return this.propertySourceList.contains(PropertySource.named(name));
@@ -85,10 +103,6 @@ public PropertySource<?> get(String name) {
 		return (index != -1 ? this.propertySourceList.get(index) : null);
 	}
 
-	@Override
-	public Iterator<PropertySource<?>> iterator() {
-		return this.propertySourceList.iterator();
-	}
 
 	/**
 	 * Add the given property source object with highest precedence.

spring-core/src/main/java/org/springframework/core/env/PropertySources.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -16,16 +16,29 @@
 
 package org.springframework.core.env;
 
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
 import org.springframework.lang.Nullable;
 
 /**
  * Holder containing one or more {@link PropertySource} objects.
  *
  * @author Chris Beams
+ * @author Juergen Hoeller
  * @since 3.1
+ * @see PropertySource
  */
 public interface PropertySources extends Iterable<PropertySource<?>> {
 
+	/**
+	 * Return a sequential {@link Stream} containing the property sources.
+	 * @since 5.1
+	 */
+	default Stream<PropertySource<?>> stream() {
+		return StreamSupport.stream(spliterator(), false);
+	}
+
 	/**
 	 * Return whether a property source with the given name is contained.
 	 * @param name the {@linkplain PropertySource#getName() name of the property source} to find

spring-core/src/test/java/org/springframework/core/env/MutablePropertySourcesTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -16,6 +16,8 @@
 
 package org.springframework.core.env;
 
+import java.util.Iterator;
+
 import org.junit.Test;
 
 import org.springframework.mock.env.MockPropertySource;
@@ -46,9 +48,9 @@ public void test() {
 		assertThat(sources.contains("g"), is(false));
 
 		assertThat(sources.get("b"), not(nullValue()));
-		assertThat(sources.get("b").getProperty("p1"), equalTo((Object)"bValue"));
+		assertThat(sources.get("b").getProperty("p1"), equalTo("bValue"));
 		assertThat(sources.get("d"), not(nullValue()));
-		assertThat(sources.get("d").getProperty("p1"), equalTo((Object)"dValue"));
+		assertThat(sources.get("d").getProperty("p1"), equalTo("dValue"));
 
 		sources.addBefore("b", new MockPropertySource("a"));
 		sources.addAfter("b", new MockPropertySource("c"));
@@ -153,4 +155,48 @@ public void getNonExistentPropertySourceReturnsNull() {
 		assertThat(sources.get("bogus"), nullValue());
 	}
 
+	@Test
+	public void iteratorContainsPropertySource() {
+		MutablePropertySources sources = new MutablePropertySources();
+		sources.addLast(new MockPropertySource("test"));
+
+		Iterator<PropertySource<?>> it = sources.iterator();
+		assertTrue(it.hasNext());
+		assertEquals("test", it.next().getName());
+
+		try {
+			it.remove();
+			fail("Should have thrown UnsupportedOperationException");
+		}
+		catch (UnsupportedOperationException ex) {
+			// expected
+		}
+		assertFalse(it.hasNext());
+	}
+
+	@Test
+	public void iteratorIsEmptyForEmptySources() {
+		MutablePropertySources sources = new MutablePropertySources();
+		Iterator<PropertySource<?>> it = sources.iterator();
+		assertFalse(it.hasNext());
+	}
+
+	@Test
+	public void streamContainsPropertySource() {
+		MutablePropertySources sources = new MutablePropertySources();
+		sources.addLast(new MockPropertySource("test"));
+
+		assertThat(sources.stream(), notNullValue());
+		assertThat(sources.stream().count(), is(1L));
+		assertThat(sources.stream().anyMatch(source -> "test".equals(source.getName())), is(true));
+		assertThat(sources.stream().anyMatch(source -> "bogus".equals(source.getName())), is(false));
+	}
+
+	@Test
+	public void streamIsEmptyForEmptySources() {
+		MutablePropertySources sources = new MutablePropertySources();
+		assertThat(sources.stream(), notNullValue());
+		assertThat(sources.stream().count(), is(0L));
+	}
+
 }