BeanWrapper supports traversal of nested paths with Java 8 Optional declarations

Issue: SPR-12241

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

@@ -33,6 +33,7 @@ import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 
 import org.apache.commons.logging.Log;
@@ -44,7 +45,9 @@ import org.springframework.core.convert.ConversionException;
 import org.springframework.core.convert.ConverterNotFoundException;
 import org.springframework.core.convert.Property;
 import org.springframework.core.convert.TypeDescriptor;
+import org.springframework.lang.UsesJava8;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 
@@ -91,6 +94,18 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 	 */
 	private static final Log logger = LogFactory.getLog(BeanWrapperImpl.class);
 
+	private static Class<?> javaUtilOptionalClass = null;
+
+	static {
+		try {
+			javaUtilOptionalClass =
+					ClassUtils.forName("java.util.Optional", BeanWrapperImpl.class.getClassLoader());
+		}
+		catch (ClassNotFoundException ex) {
+			// Java 8 not available - Optional references simply not supported then.
+		}
+	}
+
 
 	/** The wrapped object */
 	private Object object;
@@ -209,12 +224,17 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 	 */
 	public void setWrappedInstance(Object object, String nestedPath, Object rootObject) {
 		Assert.notNull(object, "Bean object must not be null");
-		this.object = object;
+		if (object.getClass().equals(javaUtilOptionalClass)) {
+			this.object = OptionalUnwrapper.unwrap(object);
+		}
+		else {
+			this.object = object;
+		}
 		this.nestedPath = (nestedPath != null ? nestedPath : "");
-		this.rootObject = (!"".equals(this.nestedPath) ? rootObject : object);
+		this.rootObject = (!"".equals(this.nestedPath) ? rootObject : this.object);
 		this.nestedBeanWrappers = null;
-		this.typeConverterDelegate = new TypeConverterDelegate(this, object);
+		this.typeConverterDelegate = new TypeConverterDelegate(this, this.object);
-		setIntrospectionClass(object.getClass());
+		setIntrospectionClass(this.object.getClass());
 	}
 
 	@Override
@@ -549,7 +569,8 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 		PropertyTokenHolder tokens = getPropertyNameTokens(nestedProperty);
 		String canonicalName = tokens.canonicalName;
 		Object propertyValue = getPropertyValue(tokens);
-		if (propertyValue == null) {
+		if (propertyValue == null ||
+				(propertyValue.getClass().equals(javaUtilOptionalClass) && OptionalUnwrapper.isEmpty(propertyValue))) {
 			if (isAutoGrowNestedPaths()) {
 				propertyValue = setDefaultValue(tokens);
 			}
@@ -1172,10 +1193,6 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 	}
 
 
-	//---------------------------------------------------------------------
-	// Inner class for internal use
-	//---------------------------------------------------------------------
-
 	private static class PropertyTokenHolder {
 
 		public String canonicalName;
@@ -1185,4 +1202,22 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 		public String[] keys;
 	}
 
+
+	/**
+	 * Inner class to avoid a hard dependency on Java 8.
+	 */
+	@UsesJava8
+	private static class OptionalUnwrapper {
+
+		public static Object unwrap(Object optionalObject) {
+			Optional<?> optional = (Optional<?>) optionalObject;
+			Assert.isTrue(optional.isPresent(), "Optional value must be present");
+			return optional.get();
+		}
+
+		public static boolean isEmpty(Object optionalObject) {
+			return !((Optional<?>) optionalObject).isPresent();
+		}
+	}
+
 }

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

@@ -28,6 +28,7 @@ import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Properties;
 import java.util.Set;
 import java.util.SortedMap;
@@ -1537,9 +1538,45 @@ public final class BeanWrapperTests extends AbstractConfigurablePropertyAccessor
 		BeanWrapperImpl bwi = new BeanWrapperImpl(foo);
 		bwi.setPropertyValue("object", "a String");
 		assertEquals("a String", foo.value);
+		assertTrue(foo.getObject() == 8);
 		assertEquals(8, bwi.getPropertyValue("object"));
 	}
 
+	@Test
+	public void testGetterWithOptional() {
+		GetterWithOptional foo = new GetterWithOptional();
+		TestBean tb = new TestBean("x");
+		BeanWrapperImpl bwi = new BeanWrapperImpl(foo);
+
+		bwi.setPropertyValue("object", tb);
+		assertSame(tb, foo.value);
+		assertSame(tb, foo.getObject().get());
+		assertSame(tb, ((Optional<String>) bwi.getPropertyValue("object")).get());
+		assertEquals("x", foo.value.getName());
+		assertEquals("x", foo.getObject().get().getName());
+		assertEquals("x", bwi.getPropertyValue("object.name"));
+
+		bwi.setPropertyValue("object.name", "y");
+		assertSame(tb, foo.value);
+		assertSame(tb, foo.getObject().get());
+		assertSame(tb, ((Optional<String>) bwi.getPropertyValue("object")).get());
+		assertEquals("y", foo.value.getName());
+		assertEquals("y", foo.getObject().get().getName());
+		assertEquals("y", bwi.getPropertyValue("object.name"));
+	}
+
+	@Test
+	public void testGetterWithOptionalAndAutoGrowing() {
+		GetterWithOptional foo = new GetterWithOptional();
+		BeanWrapperImpl bwi = new BeanWrapperImpl(foo);
+		bwi.setAutoGrowNestedPaths(true);
+
+		bwi.setPropertyValue("object.name", "x");
+		assertEquals("x", foo.value.getName());
+		assertEquals("x", foo.getObject().get().getName());
+		assertEquals("x", bwi.getPropertyValue("object.name"));
+	}
+
 	@Test
 	public void testGenericArraySetter() {
 		SkipReaderStub foo = new SkipReaderStub();
@@ -1967,6 +2004,20 @@ public final class BeanWrapperTests extends AbstractConfigurablePropertyAccessor
 	}
 
 
+	public static class GetterWithOptional {
+
+		public TestBean value;
+
+		public void setObject(TestBean object) {
+			this.value = object;
+		}
+
+		public Optional<TestBean> getObject() {
+			return Optional.ofNullable(this.value);
+		}
+	}
+
+
 	public static class SkipReaderStub<T> {
 
 		public T[] items;

spring-context/src/test/java/org/springframework/validation/beanvalidation/ValidatorFactoryTests.java

@@ -25,6 +25,7 @@ import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import javax.validation.Constraint;
 import javax.validation.ConstraintValidator;
@@ -211,6 +212,18 @@ public class ValidatorFactoryTests {
 		assertNull(rejected);
 	}
 
+	@Test
+	public void testValidationWithOptionalField() throws Exception {
+		LocalValidatorFactoryBean validator = new LocalValidatorFactoryBean();
+		validator.afterPropertiesSet();
+
+		MainBeanWithOptional mainBean = new MainBeanWithOptional();
+		Errors errors = new BeanPropertyBindingResult(mainBean, "mainBean");
+		validator.validate(mainBean, errors);
+		Object rejected = errors.getFieldValue("inner.value");
+		assertNull(rejected);
+	}
+
 
 	@NameAddressValid
 	public static class ValidPerson {
@@ -318,6 +331,17 @@ public class ValidatorFactoryTests {
 	}
 
 
+	public static class MainBeanWithOptional {
+
+		@InnerValid
+		private InnerBean inner = new InnerBean();
+
+		public Optional<InnerBean> getInner() {
+			return Optional.ofNullable(inner);
+		}
+	}
+
+
 	public static class InnerBean {
 
 		private String value;

spring-orm-hibernate4/src/test/java/org/springframework/validation/hibernatevalidator5/ValidatorFactoryTests.java

@@ -25,6 +25,7 @@ import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import javax.validation.Constraint;
 import javax.validation.ConstraintValidator;
@@ -213,6 +214,18 @@ public class ValidatorFactoryTests {
 		assertNull(rejected);
 	}
 
+	@Test
+	public void testValidationWithOptionalField() throws Exception {
+		LocalValidatorFactoryBean validator = new LocalValidatorFactoryBean();
+		validator.afterPropertiesSet();
+
+		MainBeanWithOptional mainBean = new MainBeanWithOptional();
+		Errors errors = new BeanPropertyBindingResult(mainBean, "mainBean");
+		validator.validate(mainBean, errors);
+		Object rejected = errors.getFieldValue("inner.value");
+		assertNull(rejected);
+	}
+
 
 	@NameAddressValid
 	public static class ValidPerson {
@@ -320,6 +333,17 @@ public class ValidatorFactoryTests {
 	}
 
 
+	public static class MainBeanWithOptional {
+
+		@InnerValid
+		private InnerBean inner = new InnerBean();
+
+		public Optional<InnerBean> getInner() {
+			return Optional.ofNullable(inner);
+		}
+	}
+
+
 	public static class InnerBean {
 
 		private String value;