YamlPropertiesFactoryBean consistently exposes String values

Issue: SPR-14737

spring-beans/src/main/java/org/springframework/beans/factory/config/YamlMapFactoryBean.java

@@ -19,18 +19,21 @@ package org.springframework.beans.factory.config;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Map.Entry;
-import java.util.Properties;
 
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
 
 /**
- * Factory for a Map that reads from a YAML source. YAML is a nice human-readable
- * format for configuration, and it has some useful hierarchical properties. It's
- * more or less a superset of JSON, so it has a lot of similar features. If
- * multiple resources are provided the later ones will override entries in the
- * earlier ones hierarchically - that is all entries with the same nested key of
- * type Map at any depth are merged. For example:
+ * Factory for a {@code Map} that reads from a YAML source, preserving the
+ * YAML-declared value types and their structure.
+ *
+ * <p>YAML is a nice human-readable format for configuration, and it has some
+ * useful hierarchical properties. It's more or less a superset of JSON, so it
+ * has a lot of similar features.
+ *
+ * <p>If multiple resources are provided the later ones will override entries in
+ * the earlier ones hierarchically; that is, all entries with the same nested key
+ * of type {@code Map} at any depth are merged. For example:
  *
  * <pre class="code">
  * foo:
@@ -62,6 +65,7 @@ import org.springframework.beans.factory.InitializingBean;
  * with the value in the second, but its nested values are merged.
  *
  * @author Dave Syer
+ * @author Juergen Hoeller
  * @since 4.1
  */
 public class YamlMapFactoryBean extends YamlProcessor implements FactoryBean<Map<String, Object>>, InitializingBean {
@@ -112,13 +116,9 @@ public class YamlMapFactoryBean extends YamlProcessor implements FactoryBean<Map
 	 * @see #process(java.util.Map, MatchCallback)
 	 */
 	protected Map<String, Object> createMap() {
-		final Map<String, Object> result = new LinkedHashMap<>();
-		process(new MatchCallback() {
-			@Override
-			public void process(Properties properties, Map<String, Object> map) {
-				merge(result, map);
-			}
-		});
+
+		Map<String, Object> result = new LinkedHashMap<>();
+		process((properties, map) -> merge(result, map));
 		return result;
 	}
 

spring-beans/src/main/java/org/springframework/beans/factory/config/YamlProcessor.java

@@ -37,6 +37,7 @@ import org.yaml.snakeyaml.nodes.MappingNode;
 import org.yaml.snakeyaml.parser.ParserException;
 import org.yaml.snakeyaml.reader.UnicodeReader;
 
+import org.springframework.core.CollectionFactory;
 import org.springframework.core.io.Resource;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
@@ -45,6 +46,7 @@ import org.springframework.util.StringUtils;
  * Base class for YAML factories.
  *
  * @author Dave Syer
+ * @author Juergen Hoeller
  * @since 4.1
  */
 public abstract class YamlProcessor {
@@ -217,7 +219,7 @@ public abstract class YamlProcessor {
 	}
 
 	private boolean process(Map<String, Object> map, MatchCallback callback) {
-		Properties properties = new Properties();
+		Properties properties = CollectionFactory.createStringAdaptingProperties();
 		properties.putAll(getFlattenedMap(map));
 
 		if (this.documentMatchers.isEmpty()) {
@@ -302,21 +304,23 @@ public abstract class YamlProcessor {
 				}
 			}
 			else {
-				result.put(key, value != null ? value : "");
+				result.put(key, (value != null ? value : ""));
 			}
 		}
 	}
 
 
 	/**
-	 * Callback interface used to process properties in a resulting map.
+	 * Callback interface used to process the YAML parsing results.
 	 */
 	public interface MatchCallback {
 
 		/**
-		 * Process the properties.
-		 * @param properties the properties to process
-		 * @param map a mutable result map
+		 * Process the given representation of the parsing results.
+		 * @param properties the properties to process (as a flattened
+		 * representation with indexed keys in case of a collection or map)
+		 * @param map the result map (preserving the original value structure
+		 * in the YAML document)
 		 */
 		void process(Properties properties, Map<String, Object> map);
 	}

spring-beans/src/main/java/org/springframework/beans/factory/config/YamlPropertiesFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -16,18 +16,27 @@
 
 package org.springframework.beans.factory.config;
 
-import java.util.Map;
 import java.util.Properties;
 
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.core.CollectionFactory;
 
 /**
- * Factory for Java Properties that reads from a YAML source. YAML is a nice
- * human-readable format for configuration, and it has some useful hierarchical
- * properties. It's more or less a superset of JSON, so it has a lot of similar
- * features. The Properties created by this factory have nested paths for
- * hierarchical objects, so for instance this YAML
+ * Factory for {@link java.util.Properties} that reads from a YAML source,
+ * exposing a flat structure of String property values.
+ *
+ * <p>YAML is a nice human-readable format for configuration, and it has some
+ * useful hierarchical properties. It's more or less a superset of JSON, so it
+ * has a lot of similar features.
+ *
+ * <p><b>Note: All exposed values are of type {@code String}</b> for access through
+ * the common {@link Properties#getProperty} method (e.g. in configuration property
+ * resolution through {@link PropertyResourceConfigurer#setProperties(Properties)}).
+ * If this is not desirable, use {@link YamlMapFactoryBean} instead.
+ *
+ * <p>The Properties created by this factory have nested paths for hierarchical
+ * objects, so for instance this YAML
  *
  * <pre class="code">
  * environments:
@@ -39,7 +48,7 @@ import org.springframework.beans.factory.InitializingBean;
  *     name: My Cool App
  * </pre>
  *
- * is transformed into these Properties:
+ * is transformed into these properties:
  *
  * <pre class="code">
  * environments.dev.url=http://dev.bar.com
@@ -57,7 +66,7 @@ import org.springframework.beans.factory.InitializingBean;
  * - foo.bar.com
  * </pre>
  *
- * becomes Java Properties like this:
+ * becomes properties like this:
  *
  * <pre class="code">
  * servers[0]=dev.bar.com
@@ -66,6 +75,7 @@ import org.springframework.beans.factory.InitializingBean;
  *
  * @author Dave Syer
  * @author Stephane Nicoll
+ * @author Juergen Hoeller
  * @since 4.1
  */
 public class YamlPropertiesFactoryBean extends YamlProcessor implements FactoryBean<Properties>, InitializingBean {
@@ -116,13 +126,8 @@ public class YamlPropertiesFactoryBean extends YamlProcessor implements FactoryB
 	 * @see #process(MatchCallback) ()
 	 */
 	protected Properties createProperties() {
-		final Properties result = new Properties();
-		process(new MatchCallback() {
-			@Override
-			public void process(Properties properties, Map<String, Object> map) {
-				result.putAll(properties);
-			}
-		});
+		Properties result = CollectionFactory.createStringAdaptingProperties();
+		process((properties, map) -> result.putAll(properties));
 		return result;
 	}
 

spring-beans/src/test/java/org/springframework/beans/factory/config/YamlMapFactoryBeanTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -34,43 +34,40 @@ import static org.junit.Assert.*;
  * Tests for {@link YamlMapFactoryBean}.
  *
  * @author Dave Syer
+ * @author Juergen Hoeller
  */
 public class YamlMapFactoryBeanTests {
 
 	private final YamlMapFactoryBean factory = new YamlMapFactoryBean();
 
+
 	@Test
 	public void testSetIgnoreResourceNotFound() throws Exception {
-		this.factory
-				.setResolutionMethod(YamlMapFactoryBean.ResolutionMethod.OVERRIDE_AND_IGNORE);
-		this.factory.setResources(new FileSystemResource[] {new FileSystemResource(
-				"non-exsitent-file.yml")});
+		this.factory.setResolutionMethod(YamlMapFactoryBean.ResolutionMethod.OVERRIDE_AND_IGNORE);
+		this.factory.setResources(new FileSystemResource("non-exsitent-file.yml"));
 		assertEquals(0, this.factory.getObject().size());
 	}
 
 	@Test(expected = IllegalStateException.class)
 	public void testSetBarfOnResourceNotFound() throws Exception {
-		this.factory.setResources(new FileSystemResource[] {new FileSystemResource(
-				"non-exsitent-file.yml")});
+		this.factory.setResources(new FileSystemResource("non-exsitent-file.yml"));
 		assertEquals(0, this.factory.getObject().size());
 	}
 
 	@Test
 	public void testGetObject() throws Exception {
-		this.factory.setResources(new ByteArrayResource[] {new ByteArrayResource(
-				"foo: bar".getBytes())});
+		this.factory.setResources(new ByteArrayResource("foo: bar".getBytes()));
 		assertEquals(1, this.factory.getObject().size());
 	}
 
 	@SuppressWarnings("unchecked")
 	@Test
-	public void testOverrideAndremoveDefaults() throws Exception {
-		this.factory.setResources(new ByteArrayResource[] {
-				new ByteArrayResource("foo:\n  bar: spam".getBytes()),
-				new ByteArrayResource("foo:\n  spam: bar".getBytes())});
+	public void testOverrideAndRemoveDefaults() throws Exception {
+		this.factory.setResources(new ByteArrayResource("foo:\n  bar: spam".getBytes()),
+				new ByteArrayResource("foo:\n  spam: bar".getBytes()));
+
 		assertEquals(1, this.factory.getObject().size());
-		assertEquals(2,
-				((Map<String, Object>) this.factory.getObject().get("foo")).size());
+		assertEquals(2, ((Map<String, Object>) this.factory.getObject().get("foo")).size());
 	}
 
 	@Test
@@ -81,20 +78,20 @@ public class YamlMapFactoryBeanTests {
 			public String getDescription() {
 				return "non-existent";
 			}
-
 			@Override
 			public InputStream getInputStream() throws IOException {
 				throw new IOException("planned");
 			}
 		}, new ByteArrayResource("foo:\n  spam: bar".getBytes()));
+
 		assertEquals(1, this.factory.getObject().size());
 	}
 
 	@Test
 	public void testMapWithPeriodsInKey() throws Exception {
-		this.factory.setResources(new ByteArrayResource[] {new ByteArrayResource(
-				"foo:\n  ? key1.key2\n  : value".getBytes())});
+		this.factory.setResources(new ByteArrayResource("foo:\n  ? key1.key2\n  : value".getBytes()));
 		Map<String, Object> map = this.factory.getObject();
+
 		assertEquals(1, map.size());
 		assertTrue(map.containsKey("foo"));
 		Object object = map.get("foo");
@@ -105,10 +102,24 @@ public class YamlMapFactoryBeanTests {
 		assertEquals("value", sub.get("key1.key2"));
 	}
 
+	@Test
+	public void testMapWithIntegerValue() throws Exception {
+		this.factory.setResources(new ByteArrayResource("foo:\n  ? key1.key2\n  : 3".getBytes()));
+		Map<String, Object> map = this.factory.getObject();
+
+		assertEquals(1, map.size());
+		assertTrue(map.containsKey("foo"));
+		Object object = map.get("foo");
+		assertTrue(object instanceof LinkedHashMap);
+		@SuppressWarnings("unchecked")
+		Map<String, Object> sub = (Map<String, Object>) object;
+		assertTrue(sub.containsKey("key1.key2"));
+		assertEquals(Integer.valueOf(3), sub.get("key1.key2"));
+	}
+
 	@Test(expected = ParserException.class)
 	public void testDuplicateKey() throws Exception {
-		this.factory.setResources(new ByteArrayResource[] {new ByteArrayResource(
-				"mymap:\n  foo: bar\nmymap:\n  bar: foo".getBytes())});
+		this.factory.setResources(new ByteArrayResource("mymap:\n  foo: bar\nmymap:\n  bar: foo".getBytes()));
 		this.factory.getObject().get("mymap");
 	}
 

spring-beans/src/test/java/org/springframework/beans/factory/config/YamlProcessorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.beans.factory.config;
 
 import java.util.LinkedHashMap;
@@ -24,6 +25,7 @@ import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.yaml.snakeyaml.parser.ParserException;
 import org.yaml.snakeyaml.scanner.ScannerException;
+
 import org.springframework.core.io.ByteArrayResource;
 
 import static org.junit.Assert.*;
@@ -33,34 +35,38 @@ import static org.springframework.beans.factory.config.YamlProcessor.*;
  * Tests for {@link YamlProcessor}.
  *
  * @author Dave Syer
+ * @author Juergen Hoeller
  */
 public class YamlProcessorTests {
 
-	private final YamlProcessor processor = new YamlProcessor() {
-	};
+	private final YamlProcessor processor = new YamlProcessor() {};
 
 	@Rule
 	public ExpectedException exception = ExpectedException.none();
 
+
 	@Test
 	public void arrayConvertedToIndexedBeanReference() {
-		this.processor.setResources(new ByteArrayResource(
-				"foo: bar\nbar: [1,2,3]".getBytes()));
+		this.processor.setResources(new ByteArrayResource("foo: bar\nbar: [1,2,3]".getBytes()));
 		this.processor.process(new MatchCallback() {
 			@Override
 			public void process(Properties properties, Map<String, Object> map) {
+				assertEquals(4, properties.size());
+				assertEquals("bar", properties.get("foo"));
+				assertEquals("bar", properties.getProperty("foo"));
 				assertEquals(1, properties.get("bar[0]"));
+				assertEquals("1", properties.getProperty("bar[0]"));
 				assertEquals(2, properties.get("bar[1]"));
+				assertEquals("2", properties.getProperty("bar[1]"));
 				assertEquals(3, properties.get("bar[2]"));
-				assertEquals(4, properties.size());
+				assertEquals("3", properties.getProperty("bar[2]"));
 			}
 		});
 	}
 
 	@Test
 	public void testStringResource() throws Exception {
-		this.processor.setResources(new ByteArrayResource(
-				"foo # a document that is a literal".getBytes()));
+		this.processor.setResources(new ByteArrayResource("foo # a document that is a literal".getBytes()));
 		this.processor.process(new MatchCallback() {
 			@Override
 			public void process(Properties properties, Map<String, Object> map) {
@@ -71,8 +77,7 @@ public class YamlProcessorTests {
 
 	@Test
 	public void testBadDocumentStart() throws Exception {
-		this.processor.setResources(new ByteArrayResource(
-				"foo # a document\nbar: baz".getBytes()));
+		this.processor.setResources(new ByteArrayResource("foo # a document\nbar: baz".getBytes()));
 		this.exception.expect(ParserException.class);
 		this.exception.expectMessage("line 2, column 1");
 		this.processor.process(new MatchCallback() {
@@ -84,8 +89,7 @@ public class YamlProcessorTests {
 
 	@Test
 	public void testBadResource() throws Exception {
-		this.processor.setResources(new ByteArrayResource(
-				"foo: bar\ncd\nspam:\n  foo: baz".getBytes()));
+		this.processor.setResources(new ByteArrayResource("foo: bar\ncd\nspam:\n  foo: baz".getBytes()));
 		this.exception.expect(ScannerException.class);
 		this.exception.expectMessage("line 3, column 1");
 		this.processor.process(new MatchCallback() {
@@ -97,8 +101,7 @@ public class YamlProcessorTests {
 
 	@Test
 	public void mapConvertedToIndexedBeanReference() {
-		this.processor.setResources(new ByteArrayResource(
-				"foo: bar\nbar:\n spam: bucket".getBytes()));
+		this.processor.setResources(new ByteArrayResource("foo: bar\nbar:\n spam: bucket".getBytes()));
 		this.processor.process(new MatchCallback() {
 			@Override
 			public void process(Properties properties, Map<String, Object> map) {
@@ -111,8 +114,7 @@ public class YamlProcessorTests {
 
 	@Test
 	public void integerKeyBehaves() {
-		this.processor.setResources(new ByteArrayResource(
-				"foo: bar\n1: bar".getBytes()));
+		this.processor.setResources(new ByteArrayResource("foo: bar\n1: bar".getBytes()));
 		this.processor.process(new MatchCallback() {
 			@Override
 			public void process(Properties properties, Map<String, Object> map) {
@@ -124,10 +126,8 @@ public class YamlProcessorTests {
 
 	@Test
 	public void integerDeepKeyBehaves() {
-		this.processor.setResources(new ByteArrayResource(
-				"foo:\n  1: bar".getBytes()));
+		this.processor.setResources(new ByteArrayResource("foo:\n  1: bar".getBytes()));
 		this.processor.process(new MatchCallback() {
-
 			@Override
 			public void process(Properties properties, Map<String, Object> map) {
 				assertEquals("bar", properties.get("foo[1]"));
@@ -139,8 +139,7 @@ public class YamlProcessorTests {
 	@Test
 	@SuppressWarnings("unchecked")
 	public void flattenedMapIsSameAsPropertiesButOrdered() {
-		this.processor.setResources(new ByteArrayResource(
-				"foo: bar\nbar:\n spam: bucket".getBytes()));
+		this.processor.setResources(new ByteArrayResource("foo: bar\nbar:\n spam: bucket".getBytes()));
 		this.processor.process(new MatchCallback() {
 			@Override
 			public void process(Properties properties, Map<String, Object> map) {
@@ -155,4 +154,5 @@ public class YamlProcessorTests {
 			}
 		});
 	}
+
 }

spring-beans/src/test/java/org/springframework/beans/factory/config/YamlPropertiesFactoryBeanTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -38,12 +38,14 @@ import static org.springframework.beans.factory.config.YamlProcessor.*;
  * Tests for {@link YamlPropertiesFactoryBean}.
  *
  * @author Dave Syer
+ * @author Juergen Hoeller
  */
 public class YamlPropertiesFactoryBeanTests {
 
 	@Rule
 	public ExpectedException exception = ExpectedException.none();
 
+
 	@Test
 	public void testLoadResource() throws Exception {
 		YamlPropertiesFactoryBean factory = new YamlPropertiesFactoryBean();
@@ -113,8 +115,8 @@ public class YamlPropertiesFactoryBeanTests {
 		factory.setDocumentMatchers(new DocumentMatcher() {
 			@Override
 			public MatchStatus matches(Properties properties) {
-				return "bag".equals(properties.getProperty("foo")) ? MatchStatus.FOUND
-						: MatchStatus.NOT_FOUND;
+				return ("bag".equals(properties.getProperty("foo")) ?
+						MatchStatus.FOUND : MatchStatus.NOT_FOUND);
 			}
 		});
 		Properties properties = factory.getObject();
@@ -134,8 +136,8 @@ public class YamlPropertiesFactoryBeanTests {
 				if (!properties.containsKey("foo")) {
 					return MatchStatus.ABSTAIN;
 				}
-				return "bag".equals(properties.getProperty("foo")) ? MatchStatus.FOUND
-						: MatchStatus.NOT_FOUND;
+				return ("bag".equals(properties.getProperty("foo")) ?
+						MatchStatus.FOUND : MatchStatus.NOT_FOUND);
 			}
 		});
 		Properties properties = factory.getObject();
@@ -156,8 +158,8 @@ public class YamlPropertiesFactoryBeanTests {
 				if (!properties.containsKey("foo")) {
 					return MatchStatus.ABSTAIN;
 				}
-				return "bag".equals(properties.getProperty("foo")) ? MatchStatus.FOUND
-						: MatchStatus.NOT_FOUND;
+				return ("bag".equals(properties.getProperty("foo")) ?
+						MatchStatus.FOUND : MatchStatus.NOT_FOUND);
 			}
 		});
 		Properties properties = factory.getObject();
@@ -178,8 +180,8 @@ public class YamlPropertiesFactoryBeanTests {
 				if (!properties.containsKey("foo")) {
 					return MatchStatus.ABSTAIN;
 				}
-				return "bag".equals(properties.getProperty("foo")) ? MatchStatus.FOUND
-						: MatchStatus.NOT_FOUND;
+				return ("bag".equals(properties.getProperty("foo")) ?
+						MatchStatus.FOUND : MatchStatus.NOT_FOUND);
 			}
 		});
 		Properties properties = factory.getObject();
@@ -200,8 +202,7 @@ public class YamlPropertiesFactoryBeanTests {
 	@Test
 	public void testLoadNull() throws Exception {
 		YamlPropertiesFactoryBean factory = new YamlPropertiesFactoryBean();
-		factory.setResources(new ByteArrayResource("foo: bar\nspam:"
-				.getBytes()));
+		factory.setResources(new ByteArrayResource("foo: bar\nspam:".getBytes()));
 		Properties properties = factory.getObject();
 		assertThat(properties.getProperty("foo"), equalTo("bar"));
 		assertThat(properties.getProperty("spam"), equalTo(""));
@@ -210,20 +211,28 @@ public class YamlPropertiesFactoryBeanTests {
 	@Test
 	public void testLoadArrayOfString() throws Exception {
 		YamlPropertiesFactoryBean factory = new YamlPropertiesFactoryBean();
-		factory.setResources(new ByteArrayResource("foo:\n- bar\n- baz"
-				.getBytes()));
+		factory.setResources(new ByteArrayResource("foo:\n- bar\n- baz".getBytes()));
 		Properties properties = factory.getObject();
 		assertThat(properties.getProperty("foo[0]"), equalTo("bar"));
 		assertThat(properties.getProperty("foo[1]"), equalTo("baz"));
 		assertThat(properties.get("foo"), is(nullValue()));
 	}
 
+	@Test
+	public void testLoadArrayOfInteger() throws Exception {
+		YamlPropertiesFactoryBean factory = new YamlPropertiesFactoryBean();
+		factory.setResources(new ByteArrayResource("foo:\n- 1\n- 2".getBytes()));
+		Properties properties = factory.getObject();
+		assertThat(properties.getProperty("foo[0]"), equalTo("1"));
+		assertThat(properties.getProperty("foo[1]"), equalTo("2"));
+		assertThat(properties.get("foo"), is(nullValue()));
+	}
+
 	@Test
 	public void testLoadArrayOfObject() throws Exception {
 		YamlPropertiesFactoryBean factory = new YamlPropertiesFactoryBean();
 		factory.setResources(new ByteArrayResource(
-				"foo:\n- bar:\n    spam: crap\n- baz\n- one: two\n  three: four"
-						.getBytes()
+				"foo:\n- bar:\n    spam: crap\n- baz\n- one: two\n  three: four".getBytes()
 		));
 		Properties properties = factory.getObject();
 		assertThat(properties.getProperty("foo[0].bar.spam"), equalTo("crap"));
@@ -239,8 +248,7 @@ public class YamlPropertiesFactoryBeanTests {
 		Yaml yaml = new Yaml();
 		Map<String, ?> map = yaml.loadAs("foo: bar\nspam:\n  foo: baz", Map.class);
 		assertThat(map.get("foo"), equalTo((Object) "bar"));
-		assertThat(((Map<String, Object>) map.get("spam")).get("foo"),
-				equalTo((Object) "baz"));
+		assertThat(((Map<String, Object>) map.get("spam")).get("foo"), equalTo((Object) "baz"));
 	}
 
 }

spring-core/src/main/java/org/springframework/core/CollectionFactory.java

@@ -29,6 +29,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.NavigableMap;
 import java.util.NavigableSet;
+import java.util.Properties;
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
@@ -41,12 +42,9 @@ import org.springframework.util.MultiValueMap;
 import org.springframework.util.ReflectionUtils;
 
 /**
- * Factory for collections that is aware of Java 5, Java 6, and Spring
- * collection types.
+ * Factory for collections that is aware of Java 5, Java 6, and Spring collection types.
+ *
  * <p>Mainly for internal use within the framework.
- * <p>The goal of this class is to avoid runtime dependencies on a specific
- * Java version, while nevertheless using the best collection implementation
- * that is available at runtime.
  *
  * @author Juergen Hoeller
  * @author Arjen Poutsma
@@ -325,6 +323,23 @@ public abstract class CollectionFactory {
 		}
 	}
 
+	/**
+	 * Create a variant of {@code java.util.Properties} that automatically adapts
+	 * non-String values to String representations on {@link Properties#getProperty}.
+	 * @return a new {@code Properties} instance
+	 * @since 4.3.4
+	 */
+	@SuppressWarnings("serial")
+	public static Properties createStringAdaptingProperties() {
+		return new Properties() {
+			@Override
+			public String getProperty(String key) {
+				Object value = get(key);
+				return (value != null ? value.toString() : null);
+			}
+		};
+	}
+
 	/**
 	 * Cast the given type to a subtype of {@link Enum}.
 	 * @param enumType the enum type, never {@code null}

spring-core/src/main/java/org/springframework/util/CollectionUtils.java

@@ -110,10 +110,10 @@ public abstract class CollectionUtils {
 		if (props != null) {
 			for (Enumeration<?> en = props.propertyNames(); en.hasMoreElements();) {
 				String key = (String) en.nextElement();
-				Object value = props.getProperty(key);
+				Object value = props.get(key);
 				if (value == null) {
-					// Potentially a non-String value...
-					value = props.get(key);
+					// Allow for defaults fallback or potentially overridden accessor...
+					value = props.getProperty(key);
 				}
 				map.put((K) key, (V) value);
 			}