Do not treat void and Void as simple types in BeanUtils

Prior to this commit, the isSimpleProperty() and isSimpleValueType()
methods in BeanUtils treated void and Void as simple types; however,
doing so does not make sense in this context, since void implies the
lack of a property or value.

This commit addresses this by explicitly excluding void and Void in the
logic in isSimpleValueType().

This commit also simplifies the implementation of
ViewResolutionResultHandler.supports(HandlerResult) to take advantage
of this change.

Closes gh-23573

Author: sbrannen

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -554,35 +554,42 @@ public static MethodParameter getWriteMethodParameter(PropertyDescriptor pd) {
 	}
 
 	/**
-	 * Check if the given type represents a "simple" property:
-	 * a primitive, a String or other CharSequence, a Number, a Date,
-	 * a URI, a URL, a Locale, a Class, or a corresponding array.
+	 * Check if the given type represents a "simple" property: a simple value
+	 * type or an array of simple value types.
+	 * <p>See {@link #isSimpleValueType(Class)} for the definition of <em>simple
+	 * value type</em>.
 	 * <p>Used to determine properties to check for a "simple" dependency-check.
-	 * @param clazz the type to check
+	 * @param type the type to check
 	 * @return whether the given type represents a "simple" property
 	 * @see org.springframework.beans.factory.support.RootBeanDefinition#DEPENDENCY_CHECK_SIMPLE
 	 * @see org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#checkDependencies
+	 * @see #isSimpleValueType(Class)
 	 */
-	public static boolean isSimpleProperty(Class<?> clazz) {
-		Assert.notNull(clazz, "Class must not be null");
-		return isSimpleValueType(clazz) || (clazz.isArray() && isSimpleValueType(clazz.getComponentType()));
+	public static boolean isSimpleProperty(Class<?> type) {
+		Assert.notNull(type, "'type' must not be null");
+		return isSimpleValueType(type) || (type.isArray() && isSimpleValueType(type.getComponentType()));
 	}
 
 	/**
-	 * Check if the given type represents a "simple" value type:
-	 * a primitive, an enum, a String or other CharSequence, a Number, a Date,
-	 * a URI, a URL, a Locale or a Class.
-	 * @param clazz the type to check
+	 * Check if the given type represents a "simple" value type: a primitive or
+	 * primitive wrapper, an enum, a String or other CharSequence, a Number, a
+	 * Date, a URI, a URL, a Locale, or a Class.
+	 * <p>{@code Void} and {@code void} are not considered simple value types.
+	 * @param type the type to check
 	 * @return whether the given type represents a "simple" value type
+	 * @see #isSimpleProperty(Class)
 	 */
-	public static boolean isSimpleValueType(Class<?> clazz) {
-		return (ClassUtils.isPrimitiveOrWrapper(clazz) ||
-				Enum.class.isAssignableFrom(clazz) ||
-				CharSequence.class.isAssignableFrom(clazz) ||
-				Number.class.isAssignableFrom(clazz) ||
-				Date.class.isAssignableFrom(clazz) ||
-				URI.class == clazz || URL.class == clazz ||
-				Locale.class == clazz || Class.class == clazz);
+	public static boolean isSimpleValueType(Class<?> type) {
+		return (type != void.class && type != Void.class &&
+				(ClassUtils.isPrimitiveOrWrapper(type) ||
+				Enum.class.isAssignableFrom(type) ||
+				CharSequence.class.isAssignableFrom(type) ||
+				Number.class.isAssignableFrom(type) ||
+				Date.class.isAssignableFrom(type) ||
+				URI.class == type ||
+				URL.class == type ||
+				Locale.class == type ||
+				Class.class == type));
 	}
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -19,8 +19,14 @@
 import java.beans.Introspector;
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.Method;
+import java.net.URI;
+import java.net.URL;
+import java.time.DayOfWeek;
 import java.util.ArrayList;
+import java.util.Date;
 import java.util.List;
+import java.util.Locale;
+import java.util.stream.Stream;
 
 import org.junit.Test;
 
@@ -32,14 +38,20 @@
 import org.springframework.tests.sample.beans.ITestBean;
 import org.springframework.tests.sample.beans.TestBean;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 /**
  * Unit tests for {@link BeanUtils}.
  *
  * @author Juergen Hoeller
  * @author Rob Harrop
  * @author Chris Beams
+ * @author Sam Brannen
  * @since 19.05.2003
  */
 public class BeanUtilsTests {
@@ -275,6 +287,60 @@ public void testSPR6063() {
 		}
 	}
 
+	@Test
+	public void isSimpleValueType() {
+		Stream.of(
+
+				boolean.class, char.class, byte.class, short.class, int.class,
+				long.class, float.class, double.class,
+
+				Boolean.class, Character.class, Byte.class, Short.class, Integer.class,
+				Long.class, Float.class, Double.class,
+
+				DayOfWeek.class, String.class, Date.class, URI.class, URL.class, Locale.class, Class.class
+
+		).forEach(this::assertIsSimpleValueType);
+
+		Stream.of(int[].class, Object.class, List.class, void.class, Void.class)
+			.forEach(this::assertIsNotSimpleValueType);
+	}
+
+	@Test
+	public void isSimpleProperty() {
+		Stream.of(
+
+				boolean.class, char.class, byte.class, short.class, int.class,
+				long.class, float.class, double.class,
+
+				Boolean.class, Character.class, Byte.class, Short.class, Integer.class,
+				Long.class, Float.class, Double.class,
+
+				DayOfWeek.class, String.class, Date.class, URI.class, URL.class, Locale.class, Class.class,
+
+				boolean[].class, Boolean[].class, Date[].class
+
+		).forEach(this::assertIsSimpleProperty);
+
+		Stream.of(Object.class, List.class, void.class, Void.class)
+			.forEach(this::assertIsNotSimpleProperty);
+	}
+
+	private void assertIsSimpleValueType(Class<?> type) {
+		assertTrue("Type [" + type.getName() + "] should be a simple value type", BeanUtils.isSimpleValueType(type));
+	}
+
+	private void assertIsNotSimpleValueType(Class<?> type) {
+		assertFalse("Type [" + type.getName() + "] should not be a simple value type", BeanUtils.isSimpleValueType(type));
+	}
+
+	private void assertIsSimpleProperty(Class<?> type) {
+		assertTrue("Type [" + type.getName() + "] should be a simple property", BeanUtils.isSimpleProperty(type));
+	}
+
+	private void assertIsNotSimpleProperty(Class<?> type) {
+		assertFalse("Type [" + type.getName() + "] should not be a simple property", BeanUtils.isSimpleProperty(type));
+	}
+
 	private void assertSignatureEquals(Method desiredMethod, String signature) {
 		assertEquals(desiredMethod, BeanUtils.resolveSignature(signature, MethodSignatureBean.class));
 	}
@@ -445,6 +511,7 @@ public void setValue(String aValue) {
 		}
 	}
 
+	@SuppressWarnings("unused")
 	private static class BeanWithSingleNonDefaultConstructor {
 
 		private final String name;

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/ViewResolutionResultHandler.java

@@ -160,9 +160,11 @@ public boolean supports(HandlerResult result) {
 			type = result.getReturnType().getGeneric().toClass();
 		}
 
-		return (CharSequence.class.isAssignableFrom(type) || Rendering.class.isAssignableFrom(type) ||
-				Model.class.isAssignableFrom(type) || Map.class.isAssignableFrom(type) ||
-				Void.class.equals(type) || void.class.equals(type) || View.class.isAssignableFrom(type) ||
+		return (CharSequence.class.isAssignableFrom(type) ||
+				Rendering.class.isAssignableFrom(type) ||
+				Model.class.isAssignableFrom(type) ||
+				Map.class.isAssignableFrom(type) ||
+				View.class.isAssignableFrom(type) ||
 				!BeanUtils.isSimpleProperty(type));
 	}