Consistent java.util.Optional resolution, lenient handling of optional multipart files, correct Servlet 3.0 Part list/array selection

Issue: SPR-13418
Issue: SPR-13849
Issue: SPR-13850
Issue: SPR-13893

spring-core/src/main/java/org/springframework/core/MethodParameter.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.
@@ -27,17 +27,16 @@ import java.util.HashMap;
 import java.util.Map;
 
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 
 /**
- * Helper class that encapsulates the specification of a method parameter, i.e.
- * a {@link Method} or {@link Constructor} plus a parameter index and a nested
- * type index for a declared generic type. Useful as a specification object to
- * pass along.
+ * Helper class that encapsulates the specification of a method parameter, i.e. a {@link Method}
+ * or {@link Constructor} plus a parameter index and a nested type index for a declared generic
+ * type. Useful as a specification object to pass along.
  *
- * <p>As of 4.2, there is a {@link org.springframework.core.annotation.SynthesizingMethodParameter
- * SynthesizingMethodParameter} subclass available which synthesizes annotations
- * with attribute aliases. That subclass is used for web and message endpoint
- * processing, in particular.
+ * <p>As of 4.2, there is a {@link org.springframework.core.annotation.SynthesizingMethodParameter}
+ * subclass available which synthesizes annotations with attribute aliases. That subclass is used
+ * for web and message endpoint processing, in particular.
  *
  * @author Juergen Hoeller
  * @author Rob Harrop
@@ -49,6 +48,18 @@ import org.springframework.util.Assert;
  */
 public class MethodParameter {
 
+	private static Class<?> javaUtilOptionalClass = null;
+
+	static {
+		try {
+			javaUtilOptionalClass = ClassUtils.forName("java.util.Optional", MethodParameter.class.getClassLoader());
+		}
+		catch (ClassNotFoundException ex) {
+			// Java 8 not available - Optional references simply not supported then.
+		}
+	}
+
+
 	private final Method method;
 
 	private final Constructor<?> constructor;
@@ -72,6 +83,8 @@ public class MethodParameter {
 
 	private volatile String parameterName;
 
+	private volatile MethodParameter nestedMethodParameter;
+
 
 	/**
 	 * Create a new {@code MethodParameter} for the given method, with nesting level 1.
@@ -279,6 +292,44 @@ public class MethodParameter {
 		return this.typeIndexesPerLevel;
 	}
 
+	/**
+	 * Return a variant of this {@code MethodParameter} which points to the
+	 * same parameter but one nesting level deeper. This is effectively the
+	 * same as {@link #increaseNestingLevel()}, just with an independent
+	 * {@code MethodParameter} object (e.g. in case of the original being cached).
+	 * @since 4.3
+	 */
+	public MethodParameter nested() {
+		if (this.nestedMethodParameter != null) {
+			return this.nestedMethodParameter;
+		}
+		MethodParameter nestedParam = clone();
+		nestedParam.nestingLevel = this.nestingLevel + 1;
+		this.nestedMethodParameter = nestedParam;
+		return nestedParam;
+	}
+
+	/**
+	 * Return whether this method parameter is declared as optiona
+	 * in the form of Java 8's {@link java.util.Optional}.
+	 * @since 4.3
+	 */
+	public boolean isOptional() {
+		return (getParameterType() == javaUtilOptionalClass);
+	}
+
+	/**
+	 * Return a variant of this {@code MethodParameter} which points to
+	 * the same parameter but one nesting level deeper in case of a
+	 * {@link java.util.Optional} declaration.
+	 * @since 4.3
+	 * @see #isOptional()
+	 * @see #nested()
+	 */
+	public MethodParameter nestedIfOptional() {
+		return (isOptional() ? nested() : this);
+	}
+
 
 	/**
 	 * Set a containing class to resolve the parameter type against.
@@ -370,8 +421,8 @@ public class MethodParameter {
 	/**
 	 * Return the nested generic type of the method/constructor parameter.
 	 * @return the parameter type (never {@code null})
-	 * @see #getNestingLevel()
 	 * @since 4.2
+	 * @see #getNestingLevel()
 	 */
 	public Type getNestedGenericParameterType() {
 		if (this.nestingLevel > 1) {
@@ -526,6 +577,11 @@ public class MethodParameter {
 		return (getMember().hashCode() * 31 + this.parameterIndex);
 	}
 
+	@Override
+	public MethodParameter clone() {
+		return new MethodParameter(this);
+	}
+
 
 	/**
 	 * Create a new MethodParameter for the given method or constructor.

spring-core/src/main/java/org/springframework/core/annotation/SynthesizingMethodParameter.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.
@@ -44,6 +44,10 @@ public class SynthesizingMethodParameter extends MethodParameter {
 		super(method, parameterIndex);
 	}
 
+	protected SynthesizingMethodParameter(SynthesizingMethodParameter original) {
+		super(original);
+	}
+
 
 	@Override
 	protected <A extends Annotation> A adaptAnnotation(A annotation) {
@@ -55,4 +59,10 @@ public class SynthesizingMethodParameter extends MethodParameter {
 		return AnnotationUtils.synthesizeAnnotationArray(annotations, getAnnotatedElement());
 	}
 
+
+	@Override
+	public SynthesizingMethodParameter clone() {
+		return new SynthesizingMethodParameter(this);
+	}
+
 }

spring-messaging/src/main/java/org/springframework/messaging/handler/HandlerMethod.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.
@@ -265,6 +265,10 @@ public class HandlerMethod {
 			super(HandlerMethod.this.bridgedMethod, index);
 		}
 
+		protected HandlerMethodParameter(HandlerMethodParameter original) {
+			super(original);
+		}
+
 		@Override
 		public Class<?> getContainingClass() {
 			return HandlerMethod.this.getBeanType();
@@ -274,6 +278,11 @@ public class HandlerMethod {
 		public <T extends Annotation> T getMethodAnnotation(Class<T> annotationType) {
 			return HandlerMethod.this.getMethodAnnotation(annotationType);
 		}
+
+		@Override
+		public HandlerMethodParameter clone() {
+			return new HandlerMethodParameter(this);
+		}
 	}
 
 
@@ -289,10 +298,20 @@ public class HandlerMethod {
 			this.returnValue = returnValue;
 		}
 
+		protected ReturnValueMethodParameter(ReturnValueMethodParameter original) {
+			super(original);
+			this.returnValue = original.returnValue;
+		}
+
 		@Override
 		public Class<?> getParameterType() {
 			return (this.returnValue != null ? this.returnValue.getClass() : super.getParameterType());
 		}
+
+		@Override
+		public ReturnValueMethodParameter clone() {
+			return new ReturnValueMethodParameter(this);
+		}
 	}
 
 }

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/AbstractNamedValueMethodArgumentResolver.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.
@@ -84,24 +84,24 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 
 	@Override
 	public Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception {
-		Class<?> paramType = parameter.getParameterType();
 		NamedValueInfo namedValueInfo = getNamedValueInfo(parameter);
+		MethodParameter nestedParameter = parameter.nestedIfOptional();
 
-		Object arg = resolveArgumentInternal(parameter, message, namedValueInfo.name);
+		Object arg = resolveArgumentInternal(nestedParameter, message, namedValueInfo.name);
 		if (arg == null) {
 			if (namedValueInfo.defaultValue != null) {
 				arg = resolveDefaultValue(namedValueInfo.defaultValue);
 			}
-			else if (namedValueInfo.required && !parameter.getParameterType().getName().equals("java.util.Optional")) {
-				handleMissingValue(namedValueInfo.name, parameter, message);
+			else if (namedValueInfo.required && !nestedParameter.isOptional()) {
+				handleMissingValue(namedValueInfo.name, nestedParameter, message);
 			}
-			arg = handleNullValue(namedValueInfo.name, arg, paramType);
+			arg = handleNullValue(namedValueInfo.name, arg, nestedParameter.getNestedParameterType());
 		}
 		else if ("".equals(arg) && namedValueInfo.defaultValue != null) {
 			arg = resolveDefaultValue(namedValueInfo.defaultValue);
 		}
 
-		if (!ClassUtils.isAssignableValue(paramType, arg)) {
+		if (!ClassUtils.isAssignableValue(parameter.getParameterType(), arg)) {
 			arg = this.conversionService.convert(
 					arg, TypeDescriptor.valueOf(arg.getClass()), new TypeDescriptor(parameter));
 		}

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 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.
@@ -42,6 +42,7 @@ public class DestinationVariableMethodArgumentResolver extends AbstractNamedValu
 		super(cs, null);
 	}
 
+
 	@Override
 	public boolean supportsParameter(MethodParameter parameter) {
 		return parameter.hasParameterAnnotation(DestinationVariable.class);
@@ -58,10 +59,9 @@ public class DestinationVariableMethodArgumentResolver extends AbstractNamedValu
 			throws Exception {
 
 		@SuppressWarnings("unchecked")
-		Map<String, String> vars = (Map<String, String>) message.getHeaders().get(
-				DESTINATION_TEMPLATE_VARIABLES_HEADER);
-
-		return (vars != null) ? vars.get(name) : null;
+		Map<String, String> vars =
+				(Map<String, String>) message.getHeaders().get(DESTINATION_TEMPLATE_VARIABLES_HEADER);
+		return (vars != null ? vars.get(name) : null);
 	}
 
 	@Override
@@ -77,4 +77,5 @@ public class DestinationVariableMethodArgumentResolver extends AbstractNamedValu
 			super(annotation.value(), true, ValueConstants.DEFAULT_NONE);
 		}
 	}
-}
+
+}

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethod.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.
@@ -272,6 +272,12 @@ public class InvocableHandlerMethod extends HandlerMethod {
 			this.returnType = ResolvableType.forType(super.getGenericParameterType()).getGeneric(0);
 		}
 
+		protected AsyncResultMethodParameter(AsyncResultMethodParameter original) {
+			super(original);
+			this.returnValue = original.returnValue;
+			this.returnType = original.returnType;
+		}
+
 		@Override
 		public Class<?> getParameterType() {
 			if (this.returnValue != null) {
@@ -287,6 +293,11 @@ public class InvocableHandlerMethod extends HandlerMethod {
 		public Type getGenericParameterType() {
 			return this.returnType.getType();
 		}
+
+		@Override
+		public AsyncResultMethodParameter clone() {
+			return new AsyncResultMethodParameter(this);
+		}
 	}
 
 }

spring-web/src/main/java/org/springframework/web/bind/annotation/RequestPart.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.
@@ -55,7 +55,6 @@ import org.springframework.web.multipart.MultipartResolver;
  * @author Arjen Poutsma
  * @author Sam Brannen
  * @since 3.1
- *
  * @see RequestParam
  * @see org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter
  */

spring-web/src/main/java/org/springframework/web/method/HandlerMethod.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.
@@ -280,6 +280,10 @@ public class HandlerMethod {
 			super(HandlerMethod.this.bridgedMethod, index);
 		}
 
+		protected HandlerMethodParameter(HandlerMethodParameter original) {
+			super(original);
+		}
+
 		@Override
 		public Class<?> getContainingClass() {
 			return HandlerMethod.this.getBeanType();
@@ -289,6 +293,11 @@ public class HandlerMethod {
 		public <T extends Annotation> T getMethodAnnotation(Class<T> annotationType) {
 			return HandlerMethod.this.getMethodAnnotation(annotationType);
 		}
+
+		@Override
+		public HandlerMethodParameter clone() {
+			return new HandlerMethodParameter(this);
+		}
 	}
 
 
@@ -304,10 +313,20 @@ public class HandlerMethod {
 			this.returnValue = returnValue;
 		}
 
+		protected ReturnValueMethodParameter(ReturnValueMethodParameter original) {
+			super(original);
+			this.returnValue = original.returnValue;
+		}
+
 		@Override
 		public Class<?> getParameterType() {
 			return (this.returnValue != null ? this.returnValue.getClass() : super.getParameterType());
 		}
+
+		@Override
+		public ReturnValueMethodParameter clone() {
+			return new ReturnValueMethodParameter(this);
+		}
 	}
 
 }

spring-web/src/main/java/org/springframework/web/method/annotation/AbstractCookieValueMethodArgumentResolver.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.
@@ -63,7 +63,7 @@ public abstract class AbstractCookieValueMethodArgumentResolver extends Abstract
 	@Override
 	protected void handleMissingValue(String name, MethodParameter parameter) throws ServletRequestBindingException {
 		throw new ServletRequestBindingException("Missing cookie '" + name +
-				"' for method parameter of type " + parameter.getParameterType().getSimpleName());
+				"' for method parameter of type " + parameter.getNestedParameterType().getSimpleName());
 	}
 
 

spring-web/src/main/java/org/springframework/web/method/annotation/AbstractNamedValueMethodArgumentResolver.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.
@@ -26,6 +26,7 @@ import org.springframework.beans.factory.config.BeanExpressionContext;
 import org.springframework.beans.factory.config.BeanExpressionResolver;
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.core.MethodParameter;
+import org.springframework.web.bind.ServletRequestBindingException;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.bind.annotation.ValueConstants;
 import org.springframework.web.bind.support.WebDataBinderFactory;
@@ -53,6 +54,7 @@ import org.springframework.web.method.support.ModelAndViewContainer;
  *
  * @author Arjen Poutsma
  * @author Rossen Stoyanchev
+ * @author Juergen Hoeller
  * @since 3.1
  */
 public abstract class AbstractNamedValueMethodArgumentResolver implements HandlerMethodArgumentResolver {
@@ -61,7 +63,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 
 	private final BeanExpressionContext expressionContext;
 
-	private Map<MethodParameter, NamedValueInfo> namedValueInfoCache = new ConcurrentHashMap<MethodParameter, NamedValueInfo>(256);
+	private final Map<MethodParameter, NamedValueInfo> namedValueInfoCache = new ConcurrentHashMap<MethodParameter, NamedValueInfo>(256);
 
 
 	public AbstractNamedValueMethodArgumentResolver() {
@@ -84,18 +86,18 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 	public final Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
 			NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
 
-		Class<?> paramType = parameter.getParameterType();
 		NamedValueInfo namedValueInfo = getNamedValueInfo(parameter);
+		MethodParameter nestedParameter = parameter.nestedIfOptional();
 
-		Object arg = resolveName(namedValueInfo.name, parameter, webRequest);
+		Object arg = resolveName(namedValueInfo.name, nestedParameter, webRequest);
 		if (arg == null) {
 			if (namedValueInfo.defaultValue != null) {
 				arg = resolveDefaultValue(namedValueInfo.defaultValue);
 			}
-			else if (namedValueInfo.required && !parameter.getParameterType().getName().equals("java.util.Optional")) {
-				handleMissingValue(namedValueInfo.name, parameter);
+			else if (namedValueInfo.required && !nestedParameter.isOptional()) {
+				handleMissingValue(namedValueInfo.name, nestedParameter, webRequest);
 			}
-			arg = handleNullValue(namedValueInfo.name, arg, paramType);
+			arg = handleNullValue(namedValueInfo.name, arg, nestedParameter.getNestedParameterType());
 		}
 		else if ("".equals(arg) && namedValueInfo.defaultValue != null) {
 			arg = resolveDefaultValue(namedValueInfo.defaultValue);
@@ -104,7 +106,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 		if (binderFactory != null) {
 			WebDataBinder binder = binderFactory.createBinder(webRequest, null, namedValueInfo.name);
 			try {
-				arg = binder.convertIfNecessary(arg, paramType, parameter);
+				arg = binder.convertIfNecessary(arg, parameter.getParameterType(), parameter);
 			}
 			catch (ConversionNotSupportedException ex) {
 				throw new MethodArgumentConversionNotSupportedException(arg, ex.getRequiredType(),
@@ -151,7 +153,8 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 		if (info.name.length() == 0) {
 			name = parameter.getParameterName();
 			if (name == null) {
-				throw new IllegalArgumentException("Name for argument type [" + parameter.getParameterType().getName() +
+				throw new IllegalArgumentException(
+						"Name for argument type [" + parameter.getNestedParameterType().getName() +
 						"] not available, and parameter name information not found in class file either.");
 			}
 		}
@@ -160,18 +163,19 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 	}
 
 	/**
-	 * Resolves the given parameter type and value name into an argument value.
+	 * Resolve the given parameter type and value name into an argument value.
 	 * @param name the name of the value being resolved
 	 * @param parameter the method parameter to resolve to an argument value
+	 * (pre-nested in case of a {@link java.util.Optional} declaration)
 	 * @param request the current request
-	 * @return the resolved argument. May be {@code null}
+	 * @return the resolved argument (may be {@code null})
 	 * @throws Exception in case of errors
 	 */
 	protected abstract Object resolveName(String name, MethodParameter parameter, NativeWebRequest request)
 			throws Exception;
 
 	/**
-	 * Resolves the given default value into an argument value.
+	 * Resolve the given default value into an argument value.
 	 */
 	private Object resolveDefaultValue(String defaultValue) {
 		if (this.configurableBeanFactory == null) {
@@ -185,13 +189,28 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 		return exprResolver.evaluate(placeholdersResolved, this.expressionContext);
 	}
 
+	/**
+	 * Invoked when a named value is required, but {@link #resolveName(String, MethodParameter, NativeWebRequest)}
+	 * returned {@code null} and there is no default value. Subclasses typically throw an exception in this case.
+	 * @param name the name for the value
+	 * @param parameter the method parameter
+	 * @param request the current request
+	 * @since 4.3
+	 */
+	protected void handleMissingValue(String name, MethodParameter parameter, NativeWebRequest request) throws Exception {
+		handleMissingValue(name, parameter);
+	}
+
 	/**
 	 * Invoked when a named value is required, but {@link #resolveName(String, MethodParameter, NativeWebRequest)}
 	 * returned {@code null} and there is no default value. Subclasses typically throw an exception in this case.
 	 * @param name the name for the value
 	 * @param parameter the method parameter
 	 */
-	protected abstract void handleMissingValue(String name, MethodParameter parameter) throws ServletException;
+	protected void handleMissingValue(String name, MethodParameter parameter) throws ServletException {
+		throw new ServletRequestBindingException("Missing argument '" + name +
+				"' for method parameter of type " + parameter.getNestedParameterType().getSimpleName());
+	}
 
 	/**
 	 * A {@code null} results in a {@code false} value for {@code boolean}s or an exception for other primitives.
@@ -202,7 +221,7 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 				return Boolean.FALSE;
 			}
 			else if (paramType.isPrimitive()) {
-				throw new IllegalStateException("Optional " + paramType + " parameter '" + name +
+				throw new IllegalStateException("Optional " + paramType.getSimpleName() + " parameter '" + name +
 						"' is present but cannot be translated into a null value due to being declared as a " +
 						"primitive type. Consider declaring it as object wrapper for the corresponding primitive type.");
 			}

spring-web/src/main/java/org/springframework/web/method/annotation/RequestHeaderMethodArgumentResolver.java

@@ -56,7 +56,7 @@ public class RequestHeaderMethodArgumentResolver extends AbstractNamedValueMetho
 	@Override
 	public boolean supportsParameter(MethodParameter parameter) {
 		return (parameter.hasParameterAnnotation(RequestHeader.class) &&
-				!Map.class.isAssignableFrom(parameter.getParameterType()));
+				!Map.class.isAssignableFrom(parameter.nestedIfOptional().getNestedParameterType()));
 	}
 
 	@Override
@@ -79,7 +79,7 @@ public class RequestHeaderMethodArgumentResolver extends AbstractNamedValueMetho
 	@Override
 	protected void handleMissingValue(String name, MethodParameter parameter) throws ServletRequestBindingException {
 		throw new ServletRequestBindingException("Missing request header '" + name +
-				"' for method parameter of type " + parameter.getParameterType().getSimpleName());
+				"' for method parameter of type " + parameter.getNestedParameterType().getSimpleName());
 	}
 
 

spring-web/src/main/java/org/springframework/web/method/annotation/RequestParamMethodArgumentResolver.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.
@@ -17,22 +17,17 @@
 package org.springframework.web.method.annotation;
 
 import java.beans.PropertyEditor;
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
-import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.Part;
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
-import org.springframework.core.GenericCollectionTypeResolver;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.Converter;
-import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 import org.springframework.web.bind.MissingServletRequestParameterException;
 import org.springframework.web.bind.WebDataBinder;
@@ -45,6 +40,8 @@ import org.springframework.web.multipart.MultipartException;
 import org.springframework.web.multipart.MultipartFile;
 import org.springframework.web.multipart.MultipartHttpServletRequest;
 import org.springframework.web.multipart.MultipartResolver;
+import org.springframework.web.multipart.support.MissingServletRequestPartException;
+import org.springframework.web.multipart.support.MultipartResolutionDelegate;
 import org.springframework.web.util.UriComponentsBuilder;
 import org.springframework.web.util.WebUtils;
 
@@ -124,9 +121,8 @@ public class RequestParamMethodArgumentResolver extends AbstractNamedValueMethod
 	 */
 	@Override
 	public boolean supportsParameter(MethodParameter parameter) {
-		Class<?> paramType = parameter.getParameterType();
 		if (parameter.hasParameterAnnotation(RequestParam.class)) {
-			if (Map.class.isAssignableFrom(paramType)) {
+			if (Map.class.isAssignableFrom(parameter.nestedIfOptional().getNestedParameterType())) {
 				String paramName = parameter.getParameterAnnotation(RequestParam.class).name();
 				return StringUtils.hasText(paramName);
 			}
@@ -138,11 +134,12 @@ public class RequestParamMethodArgumentResolver extends AbstractNamedValueMethod
 			if (parameter.hasParameterAnnotation(RequestPart.class)) {
 				return false;
 			}
-			else if (MultipartFile.class == paramType || "javax.servlet.http.Part".equals(paramType.getName())) {
+			parameter = parameter.nestedIfOptional();
+			if (MultipartResolutionDelegate.isMultipartArgument(parameter)) {
 				return true;
 			}
 			else if (this.useDefaultResolution) {
-				return BeanUtils.isSimpleProperty(paramType);
+				return BeanUtils.isSimpleProperty(parameter.getNestedParameterType());
 			}
 			else {
 				return false;
@@ -157,112 +154,61 @@ public class RequestParamMethodArgumentResolver extends AbstractNamedValueMethod
 	}
 
 	@Override
-	protected Object resolveName(String name, MethodParameter parameter, NativeWebRequest webRequest) throws Exception {
-		HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
+	protected Object resolveName(String name, MethodParameter parameter, NativeWebRequest request) throws Exception {
+		HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
 		MultipartHttpServletRequest multipartRequest =
 				WebUtils.getNativeRequest(servletRequest, MultipartHttpServletRequest.class);
-		Object arg;
 
-		if (MultipartFile.class == parameter.getParameterType()) {
-			assertIsMultipartRequest(servletRequest);
-			Assert.notNull(multipartRequest, "Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
-			arg = multipartRequest.getFile(name);
+		Object mpArg = MultipartResolutionDelegate.resolveMultipartArgument(name, parameter, servletRequest);
+		if (mpArg != MultipartResolutionDelegate.UNRESOLVABLE) {
+			return mpArg;
 		}
-		else if (isMultipartFileCollection(parameter)) {
-			assertIsMultipartRequest(servletRequest);
-			Assert.notNull(multipartRequest, "Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
-			arg = multipartRequest.getFiles(name);
-		}
-		else if (isMultipartFileArray(parameter)) {
-			assertIsMultipartRequest(servletRequest);
-			Assert.notNull(multipartRequest, "Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
-			List<MultipartFile> multipartFiles = multipartRequest.getFiles(name);
-			arg = multipartFiles.toArray(new MultipartFile[multipartFiles.size()]);
-		}
-		else if ("javax.servlet.http.Part".equals(parameter.getParameterType().getName())) {
-			assertIsMultipartRequest(servletRequest);
-			arg = servletRequest.getPart(name);
-		}
-		else if (isPartCollection(parameter)) {
-			assertIsMultipartRequest(servletRequest);
-			arg = new ArrayList<Object>(servletRequest.getParts());
-		}
-		else if (isPartArray(parameter)) {
-			assertIsMultipartRequest(servletRequest);
-			arg = RequestPartResolver.resolvePart(servletRequest);
-		}
-		else {
-			arg = null;
-			if (multipartRequest != null) {
-				List<MultipartFile> files = multipartRequest.getFiles(name);
-				if (!files.isEmpty()) {
-					arg = (files.size() == 1 ? files.get(0) : files);
-				}
+
+		Object arg = null;
+		if (multipartRequest != null) {
+			List<MultipartFile> files = multipartRequest.getFiles(name);
+			if (!files.isEmpty()) {
+				arg = (files.size() == 1 ? files.get(0) : files);
 			}
-			if (arg == null) {
-				String[] paramValues = webRequest.getParameterValues(name);
-				if (paramValues != null) {
-					arg = (paramValues.length == 1 ? paramValues[0] : paramValues);
-				}
+		}
+		if (arg == null) {
+			String[] paramValues = request.getParameterValues(name);
+			if (paramValues != null) {
+				arg = (paramValues.length == 1 ? paramValues[0] : paramValues);
 			}
 		}
-
 		return arg;
 	}
 
-	private void assertIsMultipartRequest(HttpServletRequest request) {
-		String contentType = request.getContentType();
-		if (contentType == null || !contentType.toLowerCase().startsWith("multipart/")) {
-			throw new MultipartException("The current request is not a multipart request");
-		}
-	}
-
-	private boolean isMultipartFileCollection(MethodParameter parameter) {
-		return (MultipartFile.class == getCollectionParameterType(parameter));
-	}
-
-	private boolean isMultipartFileArray(MethodParameter parameter) {
-		return (MultipartFile.class == parameter.getParameterType().getComponentType());
-	}
-
-	private boolean isPartCollection(MethodParameter parameter) {
-		Class<?> collectionType = getCollectionParameterType(parameter);
-		return (collectionType != null && "javax.servlet.http.Part".equals(collectionType.getName()));
-	}
-
-	private boolean isPartArray(MethodParameter parameter) {
-		Class<?> paramType = parameter.getParameterType().getComponentType();
-		return (paramType != null && "javax.servlet.http.Part".equals(paramType.getName()));
-	}
-
-	private Class<?> getCollectionParameterType(MethodParameter parameter) {
-		Class<?> paramType = parameter.getParameterType();
-		if (Collection.class == paramType || List.class.isAssignableFrom(paramType)){
-			Class<?> valueType = GenericCollectionTypeResolver.getCollectionParameterType(parameter);
-			if (valueType != null) {
-				return valueType;
+	@Override
+	protected void handleMissingValue(String name, MethodParameter parameter, NativeWebRequest request) throws Exception {
+		HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
+		if (MultipartResolutionDelegate.isMultipartArgument(parameter)) {
+			if (!MultipartResolutionDelegate.isMultipartRequest(servletRequest)) {
+				throw new MultipartException("Current request is not a multipart request");
+			}
+			else {
+				throw new MissingServletRequestPartException(name);
 			}
 		}
-		return null;
-	}
-
-	@Override
-	protected void handleMissingValue(String name, MethodParameter parameter) throws ServletException {
-		throw new MissingServletRequestParameterException(name, parameter.getParameterType().getSimpleName());
+		else {
+			throw new MissingServletRequestParameterException(name, parameter.getNestedParameterType().getSimpleName());
+		}
 	}
 
 	@Override
 	public void contributeMethodArgument(MethodParameter parameter, Object value,
 			UriComponentsBuilder builder, Map<String, Object> uriVariables, ConversionService conversionService) {
 
-		Class<?> paramType = parameter.getParameterType();
+		Class<?> paramType = parameter.getNestedParameterType();
 		if (Map.class.isAssignableFrom(paramType) || MultipartFile.class == paramType ||
 				"javax.servlet.http.Part".equals(paramType.getName())) {
 			return;
 		}
 
 		RequestParam requestParam = parameter.getParameterAnnotation(RequestParam.class);
-		String name = (requestParam == null || StringUtils.isEmpty(requestParam.name()) ? parameter.getParameterName() : requestParam.name());
+		String name = (requestParam == null || StringUtils.isEmpty(requestParam.name()) ?
+				parameter.getParameterName() : requestParam.name());
 
 		if (value == null) {
 			builder.queryParam(name);
@@ -305,12 +251,4 @@ public class RequestParamMethodArgumentResolver extends AbstractNamedValueMethod
 		}
 	}
 
-
-	private static class RequestPartResolver {
-
-		public static Object resolvePart(HttpServletRequest servletRequest) throws Exception {
-			return servletRequest.getParts().toArray(new Part[servletRequest.getParts().size()]);
-		}
-	}
-
 }

spring-web/src/main/java/org/springframework/web/multipart/support/MissingServletRequestPartException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 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.
@@ -24,27 +24,28 @@ import org.springframework.web.multipart.MultipartResolver;
  * Raised when the part of a "multipart/form-data" request identified by its
  * name cannot be found.
  *
- * <p>This may be because the request is not a multipart/form-data
- *
- * either because the part is not present in the request, or
- * because the web application is not configured correctly for processing
- * multipart requests -- e.g. no {@link MultipartResolver}.
+ * <p>This may be because the request is not a multipart/form-data request,
+ * because the part is not present in the request, or because the web
+ * application is not configured correctly for processing  multipart requests,
+ * e.g. no {@link MultipartResolver}.
  *
  * @author Rossen Stoyanchev
  * @since 3.1
  */
+@SuppressWarnings("serial")
 public class MissingServletRequestPartException extends ServletException {
 
-	private static final long serialVersionUID = -1255077391966870705L;
-
 	private final String partName;
 
+
 	public MissingServletRequestPartException(String partName) {
-		super("Required request part '" + partName + "' is not present.");
+		super("Required request part '" + partName + "' is not present");
 		this.partName = partName;
 	}
 
+
 	public String getRequestPartName() {
 		return this.partName;
 	}
+
 }

spring-web/src/main/java/org/springframework/web/multipart/support/MultipartResolutionDelegate.java

@@ -0,0 +1,197 @@
+/*
+ * 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.
+ * 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.web.multipart.support;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.Part;
+
+import org.springframework.core.GenericCollectionTypeResolver;
+import org.springframework.core.MethodParameter;
+import org.springframework.util.ClassUtils;
+import org.springframework.web.multipart.MultipartException;
+import org.springframework.web.multipart.MultipartFile;
+import org.springframework.web.multipart.MultipartHttpServletRequest;
+import org.springframework.web.util.WebUtils;
+
+/**
+ * A common delegate for {@code HandlerMethodArgumentResolver} implementations
+ * which need to resolve {@link MultipartFile} and {@link Part} arguments.
+ *
+ * @author Juergen Hoeller
+ * @since 4.3
+ */
+public abstract class MultipartResolutionDelegate {
+
+	public static final Object UNRESOLVABLE = new Object();
+
+
+	private static Class<?> servletPartClass = null;
+
+	static {
+		try {
+			servletPartClass = ClassUtils.forName(
+					"javax.servlet.http.Part", MultipartResolutionDelegate.class.getClassLoader());
+		}
+		catch (ClassNotFoundException ex) {
+			// Servlet 3.0 Part type not available - Part references simply not supported then.
+		}
+	}
+
+
+	public static boolean isMultipartRequest(HttpServletRequest request) {
+		return (WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class) != null ||
+				isMultipartContent(request));
+	}
+
+	private static boolean isMultipartContent(HttpServletRequest request) {
+		String contentType = request.getContentType();
+		return (contentType != null && contentType.toLowerCase().startsWith("multipart/"));
+	}
+
+	static MultipartHttpServletRequest asMultipartHttpServletRequest(HttpServletRequest request) {
+		MultipartHttpServletRequest unwrapped = WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
+		if (unwrapped != null) {
+			return unwrapped;
+		}
+		return adaptToMultipartHttpServletRequest(request);
+	}
+
+	private static MultipartHttpServletRequest adaptToMultipartHttpServletRequest(HttpServletRequest request) {
+		if (servletPartClass != null) {
+			// Servlet 3.0 available ..
+			return new StandardMultipartHttpServletRequest(request);
+		}
+		throw new MultipartException("Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
+	}
+
+
+	public static boolean isMultipartArgument(MethodParameter parameter) {
+		Class<?> paramType = parameter.getNestedParameterType();
+		return (MultipartFile.class == paramType || isMultipartFileCollection(parameter) ||
+				isMultipartFileArray(parameter) || servletPartClass == paramType ||
+				isPartCollection(parameter) || isPartArray(parameter));
+	}
+
+	public static Object resolveMultipartArgument(String name, MethodParameter parameter, HttpServletRequest request)
+			throws Exception {
+
+		MultipartHttpServletRequest multipartRequest =
+				WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
+		boolean isMultipart = (multipartRequest != null || isMultipartContent(request));
+
+		if (MultipartFile.class == parameter.getNestedParameterType()) {
+			if (multipartRequest == null && isMultipart) {
+				multipartRequest = adaptToMultipartHttpServletRequest(request);
+			}
+			return (multipartRequest != null ? multipartRequest.getFile(name) : null);
+		}
+		else if (isMultipartFileCollection(parameter)) {
+			if (multipartRequest == null && isMultipart) {
+				multipartRequest = adaptToMultipartHttpServletRequest(request);
+			}
+			return (multipartRequest != null ? multipartRequest.getFiles(name) : null);
+		}
+		else if (isMultipartFileArray(parameter)) {
+			if (multipartRequest == null && isMultipart) {
+				multipartRequest = adaptToMultipartHttpServletRequest(request);
+			}
+			if (multipartRequest != null) {
+				List<MultipartFile> multipartFiles = multipartRequest.getFiles(name);
+				return multipartFiles.toArray(new MultipartFile[multipartFiles.size()]);
+			}
+			else {
+				return null;
+			}
+		}
+		else if (parameter.getNestedParameterType() == servletPartClass) {
+			return (isMultipart ? RequestPartResolver.resolvePart(request, name) : null);
+		}
+		else if (isPartCollection(parameter)) {
+			return (isMultipart ? RequestPartResolver.resolvePartList(request, name) : null);
+		}
+		else if (isPartArray(parameter)) {
+			return (isMultipart ? RequestPartResolver.resolvePartArray(request, name) : null);
+		}
+		else {
+			return UNRESOLVABLE;
+		}
+	}
+
+	private static boolean isMultipartFileCollection(MethodParameter methodParam) {
+		return (MultipartFile.class == getCollectionParameterType(methodParam));
+	}
+
+	private static boolean isMultipartFileArray(MethodParameter methodParam) {
+		return (MultipartFile.class == methodParam.getNestedParameterType().getComponentType());
+	}
+
+	private static boolean isPartCollection(MethodParameter methodParam) {
+		return (servletPartClass == getCollectionParameterType(methodParam));
+	}
+
+	private static boolean isPartArray(MethodParameter methodParam) {
+		return (servletPartClass == methodParam.getNestedParameterType().getComponentType());
+	}
+
+	private static Class<?> getCollectionParameterType(MethodParameter methodParam) {
+		Class<?> paramType = methodParam.getNestedParameterType();
+		if (Collection.class == paramType || List.class.isAssignableFrom(paramType)){
+			Class<?> valueType = GenericCollectionTypeResolver.getCollectionParameterType(methodParam);
+			if (valueType != null) {
+				return valueType;
+			}
+		}
+		return null;
+	}
+
+
+	/**
+	 * Inner class to avoid hard-coded dependency on Servlet 3.0 Part type...
+	 */
+	private static class RequestPartResolver {
+
+		public static Object resolvePart(HttpServletRequest servletRequest, String name) throws Exception {
+			return servletRequest.getPart(name);
+		}
+
+		public static Object resolvePartList(HttpServletRequest servletRequest, String name) throws Exception {
+			Collection<Part> parts = servletRequest.getParts();
+			List<Part> result = new ArrayList<Part>(parts.size());
+			for (Part part : parts) {
+				if (part.getName().equals(name)) {
+					result.add(part);
+				}
+			}
+			return result;
+		}
+
+		public static Object resolvePartArray(HttpServletRequest servletRequest, String name) throws Exception {
+			Collection<Part> parts = servletRequest.getParts();
+			List<Part> result = new ArrayList<Part>(parts.size());
+			for (Part part : parts) {
+				if (part.getName().equals(name)) {
+					result.add(part);
+				}
+			}
+			return result.toArray(new Part[result.size()]);
+		}
+	}
+
+}

spring-web/src/main/java/org/springframework/web/multipart/support/RequestPartServletServerHttpRequest.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.
@@ -26,13 +26,10 @@ import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
 import org.springframework.http.server.ServerHttpRequest;
 import org.springframework.http.server.ServletServerHttpRequest;
-import org.springframework.util.ClassUtils;
 import org.springframework.web.multipart.MultipartException;
 import org.springframework.web.multipart.MultipartFile;
 import org.springframework.web.multipart.MultipartHttpServletRequest;
 import org.springframework.web.multipart.MultipartResolver;
-import org.springframework.web.util.WebUtils;
-
 
 /**
  * {@link ServerHttpRequest} implementation that accesses one part of a multipart
@@ -54,44 +51,24 @@ public class RequestPartServletServerHttpRequest extends ServletServerHttpReques
 
 
 	/**
-	 * Create a new instance.
-	 * @param request the current request
+	 * Create a new {@code RequestPartServletServerHttpRequest} instance.
+	 * @param request the current servlet request
 	 * @param partName the name of the part to adapt to the {@link ServerHttpRequest} contract
 	 * @throws MissingServletRequestPartException if the request part cannot be found
-	 * @throws IllegalArgumentException if MultipartHttpServletRequest cannot be initialized
+	 * @throws MultipartException if MultipartHttpServletRequest cannot be initialized
 	 */
 	public RequestPartServletServerHttpRequest(HttpServletRequest request, String partName)
 			throws MissingServletRequestPartException {
 
 		super(request);
 
-		this.multipartRequest = asMultipartRequest(request);
+		this.multipartRequest = MultipartResolutionDelegate.asMultipartHttpServletRequest(request);
 		this.partName = partName;
 
 		this.headers = this.multipartRequest.getMultipartHeaders(this.partName);
 		if (this.headers == null) {
-			if (request instanceof MultipartHttpServletRequest) {
-				throw new MissingServletRequestPartException(partName);
-			}
-			else {
-				throw new IllegalArgumentException(
-						"Failed to obtain request part: " + partName + ". " +
-						"The part is missing or multipart processing is not configured. " +
-						"Check for a MultipartResolver bean or if Servlet 3.0 multipart processing is enabled.");
-			}
-		}
-	}
-
-	private static MultipartHttpServletRequest asMultipartRequest(HttpServletRequest request) {
-		MultipartHttpServletRequest unwrapped = WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
-		if (unwrapped != null) {
-			return unwrapped;
-		}
-		else if (ClassUtils.hasMethod(HttpServletRequest.class, "getParts")) {
-			// Servlet 3.0 available ..
-			return new StandardMultipartHttpServletRequest(request);
+			throw new MissingServletRequestPartException(partName);
 		}
-		throw new IllegalArgumentException("Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
 	}
 
 

spring-web/src/test/java/org/springframework/web/method/annotation/RequestParamMethodArgumentResolverTests.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.
@@ -37,6 +37,7 @@ import org.springframework.mock.web.test.MockHttpServletResponse;
 import org.springframework.mock.web.test.MockMultipartFile;
 import org.springframework.mock.web.test.MockMultipartHttpServletRequest;
 import org.springframework.mock.web.test.MockPart;
+import org.springframework.util.ReflectionUtils;
 import org.springframework.web.bind.MissingServletRequestParameterException;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.bind.annotation.RequestParam;
@@ -49,6 +50,7 @@ import org.springframework.web.context.request.NativeWebRequest;
 import org.springframework.web.context.request.ServletWebRequest;
 import org.springframework.web.multipart.MultipartException;
 import org.springframework.web.multipart.MultipartFile;
+import org.springframework.web.multipart.support.MissingServletRequestPartException;
 
 import static org.junit.Assert.*;
 import static org.mockito.BDDMockito.*;
@@ -82,22 +84,18 @@ public class RequestParamMethodArgumentResolverTests {
 	private MethodParameter paramRequired;
 	private MethodParameter paramNotRequired;
 	private MethodParameter paramOptional;
+	private MethodParameter multipartFileOptional;
 
 	private NativeWebRequest webRequest;
 
 	private MockHttpServletRequest request;
 
+
 	@Before
 	public void setUp() throws Exception {
 		resolver = new RequestParamMethodArgumentResolver(null, true);
-
 		ParameterNameDiscoverer paramNameDiscoverer = new LocalVariableTableParameterNameDiscoverer();
-
-		Method method = getClass().getMethod("params", String.class, String[].class,
-				Map.class, MultipartFile.class, List.class, MultipartFile[].class,
-				Part.class, List.class, Part[].class, Map.class,
-				String.class, MultipartFile.class, List.class, Part.class,
-				MultipartFile.class, String.class, String.class, Optional.class);
+		Method method = ReflectionUtils.findMethod(getClass(), "handle", (Class<?>[]) null);
 
 		paramNamedDefaultValueString = new SynthesizingMethodParameter(method, 0);
 		paramNamedStringArray = new SynthesizingMethodParameter(method, 1);
@@ -121,27 +119,35 @@ public class RequestParamMethodArgumentResolverTests {
 		paramRequired = new SynthesizingMethodParameter(method, 15);
 		paramNotRequired = new SynthesizingMethodParameter(method, 16);
 		paramOptional = new SynthesizingMethodParameter(method, 17);
+		multipartFileOptional = new SynthesizingMethodParameter(method, 18);
 
 		request = new MockHttpServletRequest();
 		webRequest = new ServletWebRequest(request, new MockHttpServletResponse());
 	}
 
+
 	@Test
 	public void supportsParameter() {
 		resolver = new RequestParamMethodArgumentResolver(null, true);
-		assertTrue("String parameter not supported", resolver.supportsParameter(paramNamedDefaultValueString));
-		assertTrue("String array parameter not supported", resolver.supportsParameter(paramNamedStringArray));
-		assertTrue("Named map not parameter supported", resolver.supportsParameter(paramNamedMap));
-		assertTrue("MultipartFile parameter not supported", resolver.supportsParameter(paramMultipartFile));
-		assertTrue("List<MultipartFile> parameter not supported", resolver.supportsParameter(paramMultipartFileList));
-		assertTrue("MultipartFile[] parameter not supported", resolver.supportsParameter(paramMultipartFileArray));
-		assertTrue("Part parameter not supported", resolver.supportsParameter(paramPart));
-		assertTrue("List<Part> parameter not supported", resolver.supportsParameter(paramPartList));
-		assertTrue("Part[] parameter not supported", resolver.supportsParameter(paramPartArray));
-		assertFalse("non-@RequestParam parameter supported", resolver.supportsParameter(paramMap));
-		assertTrue("Simple type params supported w/o annotations", resolver.supportsParameter(paramStringNotAnnot));
-		assertTrue("MultipartFile parameter not supported", resolver.supportsParameter(paramMultipartFileNotAnnot));
-		assertTrue("Part parameter not supported", resolver.supportsParameter(paramPartNotAnnot));
+		assertTrue(resolver.supportsParameter(paramNamedDefaultValueString));
+		assertTrue(resolver.supportsParameter(paramNamedStringArray));
+		assertTrue(resolver.supportsParameter(paramNamedMap));
+		assertTrue(resolver.supportsParameter(paramMultipartFile));
+		assertTrue(resolver.supportsParameter(paramMultipartFileList));
+		assertTrue(resolver.supportsParameter(paramMultipartFileArray));
+		assertTrue(resolver.supportsParameter(paramPart));
+		assertTrue(resolver.supportsParameter(paramPartList));
+		assertTrue(resolver.supportsParameter(paramPartArray));
+		assertFalse(resolver.supportsParameter(paramMap));
+		assertTrue(resolver.supportsParameter(paramStringNotAnnot));
+		assertTrue(resolver.supportsParameter(paramMultipartFileNotAnnot));
+		assertTrue(resolver.supportsParameter(paramMultipartFileListNotAnnot));
+		assertTrue(resolver.supportsParameter(paramPartNotAnnot));
+		assertFalse(resolver.supportsParameter(paramRequestPartAnnot));
+		assertTrue(resolver.supportsParameter(paramRequired));
+		assertTrue(resolver.supportsParameter(paramNotRequired));
+		assertTrue(resolver.supportsParameter(paramOptional));
+		assertTrue(resolver.supportsParameter(multipartFileOptional));
 
 		resolver = new RequestParamMethodArgumentResolver(null, false);
 		assertFalse(resolver.supportsParameter(paramStringNotAnnot));
@@ -154,18 +160,16 @@ public class RequestParamMethodArgumentResolverTests {
 		request.addParameter("name", expected);
 
 		Object result = resolver.resolveArgument(paramNamedDefaultValueString, null, webRequest, null);
-
 		assertTrue(result instanceof String);
 		assertEquals("Invalid result", expected, result);
 	}
 
 	@Test
 	public void resolveStringArray() throws Exception {
-		String[] expected = new String[]{"foo", "bar"};
+		String[] expected = new String[] {"foo", "bar"};
 		request.addParameter("name", expected);
 
 		Object result = resolver.resolveArgument(paramNamedStringArray, null, webRequest, null);
-
 		assertTrue(result instanceof String[]);
 		assertArrayEquals("Invalid result", expected, (String[]) result);
 	}
@@ -178,7 +182,6 @@ public class RequestParamMethodArgumentResolverTests {
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramMultipartFile, null, webRequest, null);
-
 		assertTrue(result instanceof MultipartFile);
 		assertEquals("Invalid result", expected, result);
 	}
@@ -190,10 +193,10 @@ public class RequestParamMethodArgumentResolverTests {
 		MultipartFile expected2 = new MockMultipartFile("mfilelist", "Hello World 2".getBytes());
 		request.addFile(expected1);
 		request.addFile(expected2);
+		request.addFile(new MockMultipartFile("other", "Hello World 3".getBytes()));
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramMultipartFileList, null, webRequest, null);
-
 		assertTrue(result instanceof List);
 		assertEquals(Arrays.asList(expected1, expected2), result);
 	}
@@ -205,12 +208,13 @@ public class RequestParamMethodArgumentResolverTests {
 		MultipartFile expected2 = new MockMultipartFile("mfilearray", "Hello World 2".getBytes());
 		request.addFile(expected1);
 		request.addFile(expected2);
+		request.addFile(new MockMultipartFile("other", "Hello World 3".getBytes()));
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramMultipartFileArray, null, webRequest, null);
-
 		assertTrue(result instanceof MultipartFile[]);
 		MultipartFile[] parts = (MultipartFile[]) result;
+		assertEquals(2, parts.length);
 		assertEquals(parts[0], expected1);
 		assertEquals(parts[1], expected2);
 	}
@@ -225,7 +229,6 @@ public class RequestParamMethodArgumentResolverTests {
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramPart, null, webRequest, null);
-
 		assertTrue(result instanceof Part);
 		assertEquals("Invalid result", expected, result);
 	}
@@ -233,16 +236,16 @@ public class RequestParamMethodArgumentResolverTests {
 	@Test
 	public void resolvePartList() throws Exception {
 		MockHttpServletRequest request = new MockHttpServletRequest();
-		MockPart expected1 = new MockPart("pfilelist", "Hello World 1".getBytes());
-		MockPart expected2 = new MockPart("pfilelist", "Hello World 2".getBytes());
 		request.setMethod("POST");
 		request.setContentType("multipart/form-data");
+		MockPart expected1 = new MockPart("pfilelist", "Hello World 1".getBytes());
+		MockPart expected2 = new MockPart("pfilelist", "Hello World 2".getBytes());
 		request.addPart(expected1);
 		request.addPart(expected2);
+		request.addPart(new MockPart("other", "Hello World 3".getBytes()));
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramPartList, null, webRequest, null);
-
 		assertTrue(result instanceof List);
 		assertEquals(Arrays.asList(expected1, expected2), result);
 	}
@@ -256,12 +259,13 @@ public class RequestParamMethodArgumentResolverTests {
 		request.setContentType("multipart/form-data");
 		request.addPart(expected1);
 		request.addPart(expected2);
+		request.addPart(new MockPart("other", "Hello World 3".getBytes()));
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramPartArray, null, webRequest, null);
-
 		assertTrue(result instanceof Part[]);
 		Part[] parts = (Part[]) result;
+		assertEquals(2, parts.length);
 		assertEquals(parts[0], expected1);
 		assertEquals(parts[1], expected2);
 	}
@@ -274,7 +278,6 @@ public class RequestParamMethodArgumentResolverTests {
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramMultipartFileNotAnnot, null, webRequest, null);
-
 		assertTrue(result instanceof MultipartFile);
 		assertEquals("Invalid result", expected, result);
 	}
@@ -289,7 +292,6 @@ public class RequestParamMethodArgumentResolverTests {
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramMultipartFileListNotAnnot, null, webRequest, null);
-
 		assertTrue(result instanceof List);
 		assertEquals(Arrays.asList(expected1, expected2), result);
 	}
@@ -300,9 +302,7 @@ public class RequestParamMethodArgumentResolverTests {
 		fail("Expected exception: request is not a multipart request");
 	}
 
-	// SPR-9079
-
-	@Test
+	@Test  // SPR-9079
 	public void isMultipartRequestHttpPut() throws Exception {
 		MockMultipartHttpServletRequest request = new MockMultipartHttpServletRequest();
 		MultipartFile expected = new MockMultipartFile("multipartFileList", "Hello World".getBytes());
@@ -311,17 +311,23 @@ public class RequestParamMethodArgumentResolverTests {
 		webRequest = new ServletWebRequest(request);
 
 		Object actual = resolver.resolveArgument(paramMultipartFileListNotAnnot, null, webRequest, null);
-
 		assertTrue(actual instanceof List);
 		assertEquals(expected, ((List<?>) actual).get(0));
 	}
 
-	@Test(expected = IllegalArgumentException.class)
+	@Test(expected = MultipartException.class)
+	public void noMultipartContent() throws Exception {
+		request.setMethod("POST");
+		resolver.resolveArgument(paramMultipartFile, null, webRequest, null);
+		fail("Expected exception: no multipart content");
+	}
+
+	@Test(expected = MissingServletRequestPartException.class)
 	public void missingMultipartFile() throws Exception {
 		request.setMethod("POST");
 		request.setContentType("multipart/form-data");
 		resolver.resolveArgument(paramMultipartFile, null, webRequest, null);
-		fail("Expected exception: request is not MultiPartHttpServletRequest but param is MultipartFile");
+		fail("Expected exception: no such part found");
 	}
 
 	@Test
@@ -334,7 +340,6 @@ public class RequestParamMethodArgumentResolverTests {
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramPartNotAnnot, null, webRequest, null);
-
 		assertTrue(result instanceof Part);
 		assertEquals("Invalid result", expected, result);
 	}
@@ -342,7 +347,6 @@ public class RequestParamMethodArgumentResolverTests {
 	@Test
 	public void resolveDefaultValue() throws Exception {
 		Object result = resolver.resolveArgument(paramNamedDefaultValueString, null, webRequest, null);
-
 		assertTrue(result instanceof String);
 		assertEquals("Invalid result", "bar", result);
 	}
@@ -353,11 +357,8 @@ public class RequestParamMethodArgumentResolverTests {
 		fail("Expected exception");
 	}
 
-	// SPR-10578
-
-	@Test
+	@Test  // SPR-10578
 	public void missingRequestParamEmptyValueConvertedToNull() throws Exception {
-
 		WebDataBinder binder = new WebRequestDataBinder(null);
 		binder.registerCustomEditor(String.class, new StringTrimmerEditor(true));
 
@@ -367,13 +368,11 @@ public class RequestParamMethodArgumentResolverTests {
 		this.request.addParameter("stringNotAnnot", "");
 
 		Object arg = resolver.resolveArgument(paramStringNotAnnot, null, webRequest, binderFactory);
-
 		assertNull(arg);
 	}
 
 	@Test
 	public void missingRequestParamEmptyValueNotRequired() throws Exception {
-
 		WebDataBinder binder = new WebRequestDataBinder(null);
 		binder.registerCustomEditor(String.class, new StringTrimmerEditor(true));
 
@@ -383,7 +382,6 @@ public class RequestParamMethodArgumentResolverTests {
 		this.request.addParameter("name", "");
 
 		Object arg = resolver.resolveArgument(paramNotRequired, null, webRequest, binderFactory);
-
 		assertNull(arg);
 	}
 
@@ -396,17 +394,13 @@ public class RequestParamMethodArgumentResolverTests {
 		assertEquals("plainValue", result);
 	}
 
-	// SPR-8561
-
-	@Test
+	@Test  // SPR-8561
 	public void resolveSimpleTypeParamToNull() throws Exception {
 		Object result = resolver.resolveArgument(paramStringNotAnnot, null, webRequest, null);
 		assertNull(result);
 	}
 
-	// SPR-10180
-
-	@Test
+	@Test  // SPR-10180
 	public void resolveEmptyValueToDefault() throws Exception {
 		this.request.addParameter("name", "");
 		Object result = resolver.resolveArgument(paramNamedDefaultValueString, null, webRequest, null);
@@ -429,13 +423,12 @@ public class RequestParamMethodArgumentResolverTests {
 
 	@Test
 	@SuppressWarnings("rawtypes")
-	public void resolveOptional() throws Exception {
+	public void resolveOptionalParamValue() throws Exception {
 		ConfigurableWebBindingInitializer initializer = new ConfigurableWebBindingInitializer();
 		initializer.setConversionService(new DefaultConversionService());
 		WebDataBinderFactory binderFactory = new DefaultDataBinderFactory(initializer);
 
 		Object result = resolver.resolveArgument(paramOptional, null, webRequest, binderFactory);
-		assertEquals(Optional.class, result.getClass());
 		assertEquals(Optional.empty(), result);
 
 		this.request.addParameter("name", "123");
@@ -444,8 +437,46 @@ public class RequestParamMethodArgumentResolverTests {
 		assertEquals(123, ((Optional) result).get());
 	}
 
+	@Test
+	public void resolveOptionalMultipartFile() throws Exception {
+		ConfigurableWebBindingInitializer initializer = new ConfigurableWebBindingInitializer();
+		initializer.setConversionService(new DefaultConversionService());
+		WebDataBinderFactory binderFactory = new DefaultDataBinderFactory(initializer);
+
+		MockMultipartHttpServletRequest request = new MockMultipartHttpServletRequest();
+		MultipartFile expected = new MockMultipartFile("mfile", "Hello World".getBytes());
+		request.addFile(expected);
+		webRequest = new ServletWebRequest(request);
+
+		Object result = resolver.resolveArgument(multipartFileOptional, null, webRequest, binderFactory);
+		assertTrue(result instanceof Optional);
+		assertEquals("Invalid result", expected, ((Optional<?>) result).get());
+	}
+
+	@Test
+	public void missingOptionalMultipartFile() throws Exception {
+		ConfigurableWebBindingInitializer initializer = new ConfigurableWebBindingInitializer();
+		initializer.setConversionService(new DefaultConversionService());
+		WebDataBinderFactory binderFactory = new DefaultDataBinderFactory(initializer);
+
+		request.setMethod("POST");
+		request.setContentType("multipart/form-data");
+		assertEquals(Optional.empty(), resolver.resolveArgument(multipartFileOptional, null, webRequest, binderFactory));
+	}
+
+	@Test
+	public void optionalMultipartFileWithoutMultipartRequest() throws Exception {
+		ConfigurableWebBindingInitializer initializer = new ConfigurableWebBindingInitializer();
+		initializer.setConversionService(new DefaultConversionService());
+		WebDataBinderFactory binderFactory = new DefaultDataBinderFactory(initializer);
+
+		assertEquals(Optional.empty(), resolver.resolveArgument(multipartFileOptional, null, webRequest, binderFactory));
+	}
+
 
-	public void params(@RequestParam(name = "name", defaultValue = "bar") String param1,
+	@SuppressWarnings("unused")
+	public void handle(
+			@RequestParam(name = "name", defaultValue = "bar") String param1,
 			@RequestParam("name") String[] param2,
 			@RequestParam("name") Map<?, ?> param3,
 			@RequestParam("mfile") MultipartFile param4,
@@ -462,7 +493,8 @@ public class RequestParamMethodArgumentResolverTests {
 			@RequestPart MultipartFile requestPartAnnot,
 			@RequestParam("name") String paramRequired,
 			@RequestParam(name = "name", required = false) String paramNotRequired,
-			@RequestParam("name") Optional<Integer> paramOptional) {
+			@RequestParam("name") Optional<Integer> paramOptional,
+			@RequestParam("mfile") Optional<MultipartFile> multipartFileOptional) {
 	}
 
 }

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/MatrixVariableMethodArgumentResolver.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.
@@ -48,12 +48,13 @@ public class MatrixVariableMethodArgumentResolver extends AbstractNamedValueMeth
 		super(null);
 	}
 
+
 	@Override
 	public boolean supportsParameter(MethodParameter parameter) {
 		if (!parameter.hasParameterAnnotation(MatrixVariable.class)) {
 			return false;
 		}
-		if (Map.class.isAssignableFrom(parameter.getParameterType())) {
+		if (Map.class.isAssignableFrom(parameter.nestedIfOptional().getNestedParameterType())) {
 			String variableName = parameter.getParameterAnnotation(MatrixVariable.class).name();
 			return StringUtils.hasText(variableName);
 		}
@@ -67,13 +68,10 @@ public class MatrixVariableMethodArgumentResolver extends AbstractNamedValueMeth
 	}
 
 	@Override
+	@SuppressWarnings("unchecked")
 	protected Object resolveName(String name, MethodParameter parameter, NativeWebRequest request) throws Exception {
-
-		@SuppressWarnings("unchecked")
-		Map<String, MultiValueMap<String, String>> pathParameters =
-			(Map<String, MultiValueMap<String, String>>) request.getAttribute(
-					HandlerMapping.MATRIX_VARIABLES_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);
-
+		Map<String, MultiValueMap<String, String>> pathParameters = (Map<String, MultiValueMap<String, String>>)
+				request.getAttribute(HandlerMapping.MATRIX_VARIABLES_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);
 		if (CollectionUtils.isEmpty(pathParameters)) {
 			return null;
 		}
@@ -92,10 +90,10 @@ public class MatrixVariableMethodArgumentResolver extends AbstractNamedValueMeth
 			for (MultiValueMap<String, String> params : pathParameters.values()) {
 				if (params.containsKey(name)) {
 					if (found) {
-						String paramType = parameter.getParameterType().getName();
+						String paramType = parameter.getNestedParameterType().getName();
 						throw new ServletRequestBindingException(
 								"Found more than one match for URI path parameter '" + name +
-								"' for parameter type [" + paramType + "]. Use pathVar attribute to disambiguate.");
+								"' for parameter type [" + paramType + "]. Use 'pathVar' attribute to disambiguate.");
 					}
 					paramValues.addAll(params.get(name));
 					found = true;
@@ -117,7 +115,7 @@ public class MatrixVariableMethodArgumentResolver extends AbstractNamedValueMeth
 	@Override
 	protected void handleMissingValue(String name, MethodParameter parameter) throws ServletRequestBindingException {
 		throw new ServletRequestBindingException("Missing matrix variable '" + name +
-				"' for method parameter of type " + parameter.getParameterType().getSimpleName());
+				"' for method parameter of type " + parameter.getNestedParameterType().getSimpleName());
 	}
 
 
@@ -127,4 +125,5 @@ public class MatrixVariableMethodArgumentResolver extends AbstractNamedValueMeth
 			super(annotation.name(), annotation.required(), annotation.defaultValue());
 		}
 	}
-}
+
+}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/PathVariableMethodArgumentResolver.java

@@ -79,7 +79,7 @@ public class PathVariableMethodArgumentResolver extends AbstractNamedValueMethod
 		if (!parameter.hasParameterAnnotation(PathVariable.class)) {
 			return false;
 		}
-		if (Map.class.isAssignableFrom(parameter.getParameterType())) {
+		if (Map.class.isAssignableFrom(parameter.nestedIfOptional().getNestedParameterType())) {
 			String paramName = parameter.getParameterAnnotation(PathVariable.class).value();
 			return StringUtils.hasText(paramName);
 		}
@@ -95,10 +95,9 @@ public class PathVariableMethodArgumentResolver extends AbstractNamedValueMethod
 	@Override
 	@SuppressWarnings("unchecked")
 	protected Object resolveName(String name, MethodParameter parameter, NativeWebRequest request) throws Exception {
-		Map<String, String> uriTemplateVars =
-			(Map<String, String>) request.getAttribute(
-					HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);
-		return (uriTemplateVars != null) ? uriTemplateVars.get(name) : null;
+		Map<String, String> uriTemplateVars = (Map<String, String>) request.getAttribute(
+				HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);
+		return (uriTemplateVars != null ? uriTemplateVars.get(name) : null);
 	}
 
 	@Override
@@ -127,7 +126,7 @@ public class PathVariableMethodArgumentResolver extends AbstractNamedValueMethod
 	public void contributeMethodArgument(MethodParameter parameter, Object value,
 			UriComponentsBuilder builder, Map<String, Object> uriVariables, ConversionService conversionService) {
 
-		if (Map.class.isAssignableFrom(parameter.getParameterType())) {
+		if (Map.class.isAssignableFrom(parameter.getNestedParameterType())) {
 			return;
 		}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestPartMethodArgumentResolver.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.
@@ -16,20 +16,15 @@
 
 package org.springframework.web.servlet.mvc.method.annotation;
 
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Optional;
-
 import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.Part;
 
-import org.springframework.core.GenericCollectionTypeResolver;
 import org.springframework.core.MethodParameter;
 import org.springframework.http.HttpInputMessage;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.lang.UsesJava8;
-import org.springframework.util.Assert;
 import org.springframework.validation.BindingResult;
 import org.springframework.web.bind.MethodArgumentNotValidException;
 import org.springframework.web.bind.WebDataBinder;
@@ -41,12 +36,10 @@ import org.springframework.web.context.request.NativeWebRequest;
 import org.springframework.web.method.support.ModelAndViewContainer;
 import org.springframework.web.multipart.MultipartException;
 import org.springframework.web.multipart.MultipartFile;
-import org.springframework.web.multipart.MultipartHttpServletRequest;
 import org.springframework.web.multipart.MultipartResolver;
 import org.springframework.web.multipart.support.MissingServletRequestPartException;
+import org.springframework.web.multipart.support.MultipartResolutionDelegate;
 import org.springframework.web.multipart.support.RequestPartServletServerHttpRequest;
-import org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver;
-import org.springframework.web.util.WebUtils;
 
 /**
  * Resolves the following method arguments:
@@ -65,12 +58,13 @@ import org.springframework.web.util.WebUtils;
  * it is derived from the name of the method argument.
  *
  * <p>Automatic validation may be applied if the argument is annotated with
- * {@code @javax.validation.Valid}. In case of validation failure, a
- * {@link MethodArgumentNotValidException} is raised and a 400 response status
- * code returned if {@link DefaultHandlerExceptionResolver} is configured.
+ * {@code @javax.validation.Valid}. In case of validation failure, a {@link MethodArgumentNotValidException}
+ * is raised and a 400 response status code returned if
+ * {@link org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver} is configured.
  *
  * @author Rossen Stoyanchev
  * @author Brian Clozel
+ * @author Juergen Hoeller
  * @since 3.1
  */
 public class RequestPartMethodArgumentResolver extends AbstractMessageConverterMethodArgumentResolver {
@@ -107,18 +101,10 @@ public class RequestPartMethodArgumentResolver extends AbstractMessageConverterM
 			return true;
 		}
 		else {
-			if (parameter.hasParameterAnnotation(RequestParam.class)){
-				return false;
-			}
-			else if (MultipartFile.class == parameter.getParameterType()) {
-				return true;
-			}
-			else if ("javax.servlet.http.Part".equals(parameter.getParameterType().getName())) {
-				return true;
-			}
-			else {
+			if (parameter.hasParameterAnnotation(RequestParam.class)) {
 				return false;
 			}
+			return MultipartResolutionDelegate.isMultipartArgument(parameter.nestedIfOptional());
 		}
 	}
 
@@ -128,87 +114,58 @@ public class RequestPartMethodArgumentResolver extends AbstractMessageConverterM
 			NativeWebRequest request, WebDataBinderFactory binderFactory) throws Exception {
 
 		HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
-		assertIsMultipartRequest(servletRequest);
-
-		MultipartHttpServletRequest multipartRequest =
-				WebUtils.getNativeRequest(servletRequest, MultipartHttpServletRequest.class);
-
-		Class<?> paramType = parameter.getParameterType();
-		boolean optional = paramType.getName().equals("java.util.Optional");
-		if (optional) {
-			parameter.increaseNestingLevel();
-			paramType = parameter.getNestedParameterType();
-		}
+		RequestPart requestPart = parameter.getParameterAnnotation(RequestPart.class);
+		boolean isRequired = ((requestPart == null || requestPart.required()) && !parameter.isOptional());
 
-		String partName = getPartName(parameter);
-		Object arg;
+		String name = getPartName(parameter, requestPart);
+		parameter = parameter.nestedIfOptional();
+		Object arg = null;
 
-		if (MultipartFile.class == paramType) {
-			Assert.notNull(multipartRequest, "Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
-			arg = multipartRequest.getFile(partName);
-		}
-		else if (isMultipartFileCollection(parameter)) {
-			Assert.notNull(multipartRequest, "Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
-			arg = multipartRequest.getFiles(partName);
-		}
-		else if (isMultipartFileArray(parameter)) {
-			Assert.notNull(multipartRequest, "Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
-			List<MultipartFile> files = multipartRequest.getFiles(partName);
-			arg = files.toArray(new MultipartFile[files.size()]);
-		}
-		else if ("javax.servlet.http.Part".equals(paramType.getName())) {
-			assertIsMultipartRequest(servletRequest);
-			arg = servletRequest.getPart(partName);
-		}
-		else if (isPartCollection(parameter)) {
-			assertIsMultipartRequest(servletRequest);
-			arg = new ArrayList<Object>(servletRequest.getParts());
-		}
-		else if (isPartArray(parameter)) {
-			assertIsMultipartRequest(servletRequest);
-			arg = RequestPartResolver.resolvePart(servletRequest);
+		Object mpArg = MultipartResolutionDelegate.resolveMultipartArgument(name, parameter, servletRequest);
+		if (mpArg != MultipartResolutionDelegate.UNRESOLVABLE) {
+			arg = mpArg;
 		}
 		else {
 			try {
-				HttpInputMessage inputMessage = new RequestPartServletServerHttpRequest(servletRequest, partName);
+				HttpInputMessage inputMessage = new RequestPartServletServerHttpRequest(servletRequest, name);
 				arg = readWithMessageConverters(inputMessage, parameter, parameter.getNestedGenericParameterType());
-				WebDataBinder binder = binderFactory.createBinder(request, arg, partName);
+				WebDataBinder binder = binderFactory.createBinder(request, arg, name);
 				if (arg != null) {
 					validateIfApplicable(binder, parameter);
 					if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
 						throw new MethodArgumentNotValidException(parameter, binder.getBindingResult());
 					}
 				}
-				mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + partName, binder.getBindingResult());
+				mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult());
 			}
 			catch (MissingServletRequestPartException ex) {
-				// handled below
-				arg = null;
+				if (isRequired) {
+					throw ex;
+				}
+			}
+			catch (MultipartException ex) {
+				if (isRequired) {
+					throw ex;
+				}
 			}
 		}
 
-		RequestPart requestPart = parameter.getParameterAnnotation(RequestPart.class);
-		boolean isRequired = ((requestPart == null || requestPart.required()) && !optional);
-
 		if (arg == null && isRequired) {
-			throw new MissingServletRequestPartException(partName);
+			if (!MultipartResolutionDelegate.isMultipartRequest(servletRequest)) {
+				throw new MultipartException("Current request is not a multipart request");
+			}
+			else {
+				throw new MissingServletRequestPartException(name);
+			}
 		}
-		if (optional) {
-			arg = Optional.ofNullable(arg);
+		if (parameter.isOptional()) {
+			arg = OptionalResolver.resolveValue(arg);
 		}
 
 		return arg;
 	}
 
-	private static void assertIsMultipartRequest(HttpServletRequest request) {
-		String contentType = request.getContentType();
-		if (contentType == null || !contentType.toLowerCase().startsWith("multipart/")) {
-			throw new MultipartException("The current request is not a multipart request");
-		}
-	}
-
-	private String getPartName(MethodParameter methodParam) {
-		RequestPart requestPart = methodParam.getParameterAnnotation(RequestPart.class);
+	private String getPartName(MethodParameter methodParam, RequestPart requestPart) {
 		String partName = (requestPart != null ? requestPart.name() : "");
 		if (partName.length() == 0) {
 			partName = methodParam.getParameterName();
@@ -221,46 +178,18 @@ public class RequestPartMethodArgumentResolver extends AbstractMessageConverterM
 		return partName;
 	}
 
-	private boolean isMultipartFileCollection(MethodParameter methodParam) {
-		Class<?> collectionType = getCollectionParameterType(methodParam);
-		return MultipartFile.class == collectionType;
-	}
-
-	private boolean isMultipartFileArray(MethodParameter methodParam) {
-		Class<?> paramType = methodParam.getNestedParameterType().getComponentType();
-		return MultipartFile.class == paramType;
-	}
-
-	private boolean isPartCollection(MethodParameter methodParam) {
-		Class<?> collectionType = getCollectionParameterType(methodParam);
-		return (collectionType != null && "javax.servlet.http.Part".equals(collectionType.getName()));
-	}
-
-	private boolean isPartArray(MethodParameter methodParam) {
-		Class<?> paramType = methodParam.getNestedParameterType().getComponentType();
-		return (paramType != null && "javax.servlet.http.Part".equals(paramType.getName()));
-	}
-
-	private Class<?> getCollectionParameterType(MethodParameter methodParam) {
-		Class<?> paramType = methodParam.getNestedParameterType();
-		if (Collection.class == paramType || List.class.isAssignableFrom(paramType)){
-			Class<?> valueType = GenericCollectionTypeResolver.getCollectionParameterType(methodParam);
-			if (valueType != null) {
-				return valueType;
-			}
-		}
-		return null;
-	}
-
 
 	/**
-	 * Inner class to avoid hard-coded dependency on Servlet 3.0 Part type...
+	 * Inner class to avoid hard-coded dependency on Java 8 Optional type...
 	 */
-	private static class RequestPartResolver {
+	private static class OptionalResolver {
 
-		public static Object resolvePart(HttpServletRequest servletRequest) throws Exception {
-			Collection<Part> parts = servletRequest.getParts();
-			return parts.toArray(new Part[parts.size()]);
+		public static Object resolveValue(Object value) {
+			if (value == null || (value instanceof Collection && ((Collection) value).isEmpty()) ||
+					(value instanceof Object[] && ((Object[]) value).length == 0)) {
+				return Optional.empty();
+			}
+			return Optional.of(value);
 		}
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ServletCookieValueMethodArgumentResolver.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.
@@ -52,7 +52,7 @@ public class ServletCookieValueMethodArgumentResolver extends AbstractCookieValu
 	protected Object resolveName(String cookieName, MethodParameter parameter, NativeWebRequest webRequest) throws Exception {
 		HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
 		Cookie cookieValue = WebUtils.getCookie(servletRequest, cookieName);
-		if (Cookie.class.isAssignableFrom(parameter.getParameterType())) {
+		if (Cookie.class.isAssignableFrom(parameter.getNestedParameterType())) {
 			return cookieValue;
 		}
 		else if (cookieValue != null) {

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ServletInvocableHandlerMethod.java

@@ -262,6 +262,12 @@ public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
 			this.returnType = ResolvableType.forType(super.getGenericParameterType()).getGeneric(0);
 		}
 
+		public ConcurrentResultMethodParameter(ConcurrentResultMethodParameter original) {
+			super(original);
+			this.returnValue = original.returnValue;
+			this.returnType = original.returnType;
+		}
+
 		@Override
 		public Class<?> getParameterType() {
 			if (this.returnValue != null) {
@@ -283,6 +289,11 @@ public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
 		public Type getGenericParameterType() {
 			return this.returnType.getType();
 		}
+
+		@Override
+		public ConcurrentResultMethodParameter clone() {
+			return new ConcurrentResultMethodParameter(this);
+		}
 	}
 
 }

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/RequestPartMethodArgumentResolverTests.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.
@@ -41,6 +41,7 @@ import org.springframework.mock.web.test.MockHttpServletResponse;
 import org.springframework.mock.web.test.MockMultipartFile;
 import org.springframework.mock.web.test.MockMultipartHttpServletRequest;
 import org.springframework.mock.web.test.MockPart;
+import org.springframework.util.ReflectionUtils;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 import org.springframework.web.bind.MethodArgumentNotValidException;
 import org.springframework.web.bind.WebDataBinder;
@@ -53,7 +54,6 @@ import org.springframework.web.method.support.ModelAndViewContainer;
 import org.springframework.web.multipart.MultipartException;
 import org.springframework.web.multipart.MultipartFile;
 import org.springframework.web.multipart.support.MissingServletRequestPartException;
-import org.springframework.web.multipart.support.RequestPartServletServerHttpRequest;
 
 import static org.junit.Assert.*;
 import static org.mockito.BDDMockito.*;
@@ -86,7 +86,9 @@ public class RequestPartMethodArgumentResolverTests {
 	private MethodParameter paramPartArray;
 	private MethodParameter paramRequestParamAnnot;
 	private MethodParameter optionalMultipartFile;
+	private MethodParameter optionalMultipartFileList;
 	private MethodParameter optionalPart;
+	private MethodParameter optionalPartList;
 	private MethodParameter optionalRequestPart;
 
 	private NativeWebRequest webRequest;
@@ -97,10 +99,7 @@ public class RequestPartMethodArgumentResolverTests {
 	@SuppressWarnings("unchecked")
 	@Before
 	public void setUp() throws Exception {
-		Method method = getClass().getMethod("handle", SimpleBean.class, SimpleBean.class,
-				SimpleBean.class, MultipartFile.class, List.class, MultipartFile[].class,
-				Integer.TYPE, MultipartFile.class, Part.class, List.class, Part[].class,
-				MultipartFile.class, Optional.class, Optional.class, Optional.class);
+		Method method = ReflectionUtils.findMethod(getClass(), "handle", (Class<?>[]) null);
 
 		paramRequestPart = new SynthesizingMethodParameter(method, 0);
 		paramRequestPart.initParameterNameDiscovery(new LocalVariableTableParameterNameDiscoverer());
@@ -119,9 +118,13 @@ public class RequestPartMethodArgumentResolverTests {
 		paramRequestParamAnnot = new SynthesizingMethodParameter(method, 11);
 		optionalMultipartFile = new SynthesizingMethodParameter(method, 12);
 		optionalMultipartFile.initParameterNameDiscovery(new LocalVariableTableParameterNameDiscoverer());
-		optionalPart = new SynthesizingMethodParameter(method, 13);
+		optionalMultipartFileList = new SynthesizingMethodParameter(method, 13);
+		optionalMultipartFileList.initParameterNameDiscovery(new LocalVariableTableParameterNameDiscoverer());
+		optionalPart = new SynthesizingMethodParameter(method, 14);
 		optionalPart.initParameterNameDiscovery(new LocalVariableTableParameterNameDiscoverer());
-		optionalRequestPart = new SynthesizingMethodParameter(method, 14);
+		optionalPartList = new SynthesizingMethodParameter(method, 15);
+		optionalPartList.initParameterNameDiscovery(new LocalVariableTableParameterNameDiscoverer());
+		optionalRequestPart = new SynthesizingMethodParameter(method, 16);
 
 		messageConverter = mock(HttpMessageConverter.class);
 		given(messageConverter.getSupportedMediaTypes()).willReturn(Collections.singletonList(MediaType.TEXT_PLAIN));
@@ -136,35 +139,41 @@ public class RequestPartMethodArgumentResolverTests {
 		multipartRequest = new MockMultipartHttpServletRequest();
 		multipartRequest.addFile(multipartFile1);
 		multipartRequest.addFile(multipartFile2);
+		multipartRequest.addFile(new MockMultipartFile("otherPart", "", "text/plain", content));
 		webRequest = new ServletWebRequest(multipartRequest, new MockHttpServletResponse());
 	}
 
 
 	@Test
 	public void supportsParameter() {
-		assertTrue("RequestPart parameter not supported", resolver.supportsParameter(paramRequestPart));
-		assertTrue("MultipartFile parameter not supported", resolver.supportsParameter(paramMultipartFileNotAnnot));
-		assertTrue("Part parameter not supported", resolver.supportsParameter(paramPart));
-		assertTrue("List<Part> parameter not supported", resolver.supportsParameter(paramPartList));
-		assertTrue("Part[] parameter not supported", resolver.supportsParameter(paramPartArray));
-		assertTrue("MultipartFile parameter not supported", resolver.supportsParameter(paramMultipartFile));
-		assertTrue("List<MultipartFile> parameter not supported", resolver.supportsParameter(paramMultipartFileList));
-		assertTrue("MultipartFile[] parameter not supported", resolver.supportsParameter(paramMultipartFileArray));
-		assertFalse("non-RequestPart parameter should not be supported", resolver.supportsParameter(paramInt));
-		assertFalse("@RequestParam args should not be supported", resolver.supportsParameter(paramRequestParamAnnot));
+		assertTrue(resolver.supportsParameter(paramRequestPart));
+		assertTrue(resolver.supportsParameter(paramNamedRequestPart));
+		assertTrue(resolver.supportsParameter(paramValidRequestPart));
+		assertTrue(resolver.supportsParameter(paramMultipartFile));
+		assertTrue(resolver.supportsParameter(paramMultipartFileList));
+		assertTrue(resolver.supportsParameter(paramMultipartFileArray));
+		assertFalse(resolver.supportsParameter(paramInt));
+		assertTrue(resolver.supportsParameter(paramMultipartFileNotAnnot));
+		assertTrue(resolver.supportsParameter(paramPart));
+		assertTrue(resolver.supportsParameter(paramPartList));
+		assertTrue(resolver.supportsParameter(paramPartArray));
+		assertFalse(resolver.supportsParameter(paramRequestParamAnnot));
+		assertTrue(resolver.supportsParameter(optionalMultipartFile));
+		assertTrue(resolver.supportsParameter(optionalMultipartFileList));
+		assertTrue(resolver.supportsParameter(optionalPart));
+		assertTrue(resolver.supportsParameter(optionalPartList));
+		assertTrue(resolver.supportsParameter(optionalRequestPart));
 	}
 
 	@Test
 	public void resolveMultipartFile() throws Exception {
 		Object actual = resolver.resolveArgument(paramMultipartFile, null, webRequest, null);
-		assertNotNull(actual);
 		assertSame(multipartFile1, actual);
 	}
 
 	@Test
 	public void resolveMultipartFileList() throws Exception {
 		Object actual = resolver.resolveArgument(paramMultipartFileList, null, webRequest, null);
-		assertNotNull(actual);
 		assertTrue(actual instanceof List);
 		assertEquals(Arrays.asList(multipartFile1, multipartFile2), actual);
 	}
@@ -175,6 +184,7 @@ public class RequestPartMethodArgumentResolverTests {
 		assertNotNull(actual);
 		assertTrue(actual instanceof MultipartFile[]);
 		MultipartFile[] parts = (MultipartFile[]) actual;
+		assertEquals(2, parts.length);
 		assertEquals(parts[0], multipartFile1);
 		assertEquals(parts[1], multipartFile2);
 	}
@@ -184,6 +194,7 @@ public class RequestPartMethodArgumentResolverTests {
 		MockMultipartHttpServletRequest request = new MockMultipartHttpServletRequest();
 		MultipartFile expected = new MockMultipartFile("multipartFileNotAnnot", "Hello World".getBytes());
 		request.addFile(expected);
+		request.addFile(new MockMultipartFile("otherPart", "", "text/plain", "Hello World".getBytes()));
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramMultipartFileNotAnnot, null, webRequest, null);
@@ -194,52 +205,52 @@ public class RequestPartMethodArgumentResolverTests {
 
 	@Test
 	public void resolvePartArgument() throws Exception {
-		MockPart expected = new MockPart("part", "Hello World".getBytes());
 		MockHttpServletRequest request = new MockHttpServletRequest();
 		request.setMethod("POST");
 		request.setContentType("multipart/form-data");
+		MockPart expected = new MockPart("part", "Hello World".getBytes());
 		request.addPart(expected);
+		request.addPart(new MockPart("otherPart", "Hello World".getBytes()));
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramPart, null, webRequest, null);
-
 		assertTrue(result instanceof Part);
 		assertEquals("Invalid result", expected, result);
 	}
 
 	@Test
 	public void resolvePartListArgument() throws Exception {
-		MockPart part1 = new MockPart("requestPart1", "Hello World 1".getBytes());
-		MockPart part2 = new MockPart("requestPart2", "Hello World 2".getBytes());
 		MockHttpServletRequest request = new MockHttpServletRequest();
 		request.setMethod("POST");
 		request.setContentType("multipart/form-data");
+		MockPart part1 = new MockPart("requestPart", "Hello World 1".getBytes());
+		MockPart part2 = new MockPart("requestPart", "Hello World 2".getBytes());
 		request.addPart(part1);
 		request.addPart(part2);
+		request.addPart(new MockPart("otherPart", "Hello World".getBytes()));
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramPartList, null, webRequest, null);
-
 		assertTrue(result instanceof List);
 		assertEquals(Arrays.asList(part1, part2), result);
 	}
 
 	@Test
 	public void resolvePartArrayArgument() throws Exception {
-		MockPart part1 = new MockPart("requestPart1", "Hello World 1".getBytes());
-		MockPart part2 = new MockPart("requestPart2", "Hello World 2".getBytes());
 		MockHttpServletRequest request = new MockHttpServletRequest();
 		request.setMethod("POST");
 		request.setContentType("multipart/form-data");
+		MockPart part1 = new MockPart("requestPart", "Hello World 1".getBytes());
+		MockPart part2 = new MockPart("requestPart", "Hello World 2".getBytes());
 		request.addPart(part1);
 		request.addPart(part2);
+		request.addPart(new MockPart("otherPart", "Hello World".getBytes()));
 		webRequest = new ServletWebRequest(request);
 
 		Object result = resolver.resolveArgument(paramPartArray, null, webRequest, null);
-
 		assertTrue(result instanceof Part[]);
 		Part[] parts = (Part[]) result;
-		assertThat(parts, Matchers.arrayWithSize(2));
+		assertEquals(2, parts.length);
 		assertEquals(parts[0], part1);
 		assertEquals(parts[1], part2);
 	}
@@ -302,8 +313,8 @@ public class RequestPartMethodArgumentResolverTests {
 	@Test  // SPR-9079
 	public void isMultipartRequestPut() throws Exception {
 		this.multipartRequest.setMethod("PUT");
-		Object actual = resolver.resolveArgument(paramMultipartFile, null, webRequest, null);
-		assertSame(multipartFile1, actual);
+		Object actualValue = resolver.resolveArgument(paramMultipartFile, null, webRequest, null);
+		assertSame(multipartFile1, actualValue);
 	}
 
 	@Test
@@ -311,12 +322,16 @@ public class RequestPartMethodArgumentResolverTests {
 		MockMultipartHttpServletRequest request = new MockMultipartHttpServletRequest();
 		MultipartFile expected = new MockMultipartFile("optionalMultipartFile", "Hello World".getBytes());
 		request.addFile(expected);
+		request.addFile(new MockMultipartFile("otherPart", "", "text/plain", "Hello World".getBytes()));
 		webRequest = new ServletWebRequest(request);
 
-		Object result = resolver.resolveArgument(optionalMultipartFile, null, webRequest, null);
+		Object actualValue = resolver.resolveArgument(optionalMultipartFile, null, webRequest, null);
+		assertTrue(actualValue instanceof Optional);
+		assertEquals("Invalid result", expected, ((Optional) actualValue).get());
 
-		assertTrue(result instanceof Optional);
-		assertEquals("Invalid result", expected, ((Optional) result).get());
+		actualValue = resolver.resolveArgument(optionalMultipartFile, null, webRequest, null);
+		assertTrue(actualValue instanceof Optional);
+		assertEquals("Invalid result", expected, ((Optional) actualValue).get());
 	}
 
 	@Test
@@ -324,10 +339,62 @@ public class RequestPartMethodArgumentResolverTests {
 		MockMultipartHttpServletRequest request = new MockMultipartHttpServletRequest();
 		webRequest = new ServletWebRequest(request);
 
-		Object result = resolver.resolveArgument(optionalMultipartFile, null, webRequest, null);
+		Object actualValue = resolver.resolveArgument(optionalMultipartFile, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+
+		actualValue = resolver.resolveArgument(optionalMultipartFile, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+	}
+
+	@Test
+	public void resolveOptionalMultipartFileArgumentWithoutMultipartRequest() throws Exception {
+		webRequest = new ServletWebRequest(new MockHttpServletRequest());
+
+		Object actualValue = resolver.resolveArgument(optionalMultipartFile, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+
+		actualValue = resolver.resolveArgument(optionalMultipartFile, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+	}
+
+	@Test
+	public void resolveOptionalMultipartFileList() throws Exception {
+		MockMultipartHttpServletRequest request = new MockMultipartHttpServletRequest();
+		MultipartFile expected = new MockMultipartFile("requestPart", "Hello World".getBytes());
+		request.addFile(expected);
+		request.addFile(new MockMultipartFile("otherPart", "", "text/plain", "Hello World".getBytes()));
+		webRequest = new ServletWebRequest(request);
+
+		Object actualValue = resolver.resolveArgument(optionalMultipartFileList, null, webRequest, null);
+		assertTrue(actualValue instanceof Optional);
+		assertEquals("Invalid result", Collections.singletonList(expected), ((Optional) actualValue).get());
 
-		assertTrue(result instanceof Optional);
-		assertFalse("Invalid result", ((Optional) result).isPresent());
+		actualValue = resolver.resolveArgument(optionalMultipartFileList, null, webRequest, null);
+		assertTrue(actualValue instanceof Optional);
+		assertEquals("Invalid result", Collections.singletonList(expected), ((Optional) actualValue).get());
+	}
+
+	@Test
+	public void resolveOptionalMultipartFileListNotPresent() throws Exception {
+		MockMultipartHttpServletRequest request = new MockMultipartHttpServletRequest();
+		webRequest = new ServletWebRequest(request);
+
+		Object actualValue = resolver.resolveArgument(optionalMultipartFileList, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+
+		actualValue = resolver.resolveArgument(optionalMultipartFileList, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+	}
+
+	@Test
+	public void resolveOptionalMultipartFileListWithoutMultipartRequest() throws Exception {
+		webRequest = new ServletWebRequest(new MockHttpServletRequest());
+
+		Object actualValue = resolver.resolveArgument(optionalMultipartFileList, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+
+		actualValue = resolver.resolveArgument(optionalMultipartFileList, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
 	}
 
 	@Test
@@ -337,12 +404,16 @@ public class RequestPartMethodArgumentResolverTests {
 		request.setMethod("POST");
 		request.setContentType("multipart/form-data");
 		request.addPart(expected);
+		request.addPart(new MockPart("otherPart", "Hello World".getBytes()));
 		webRequest = new ServletWebRequest(request);
 
-		Object result = resolver.resolveArgument(optionalPart, null, webRequest, null);
+		Object actualValue = resolver.resolveArgument(optionalPart, null, webRequest, null);
+		assertTrue(actualValue instanceof Optional);
+		assertEquals("Invalid result", expected, ((Optional) actualValue).get());
 
-		assertTrue(result instanceof Optional);
-		assertEquals("Invalid result", expected, ((Optional) result).get());
+		actualValue = resolver.resolveArgument(optionalPart, null, webRequest, null);
+		assertTrue(actualValue instanceof Optional);
+		assertEquals("Invalid result", expected, ((Optional) actualValue).get());
 	}
 
 	@Test
@@ -352,36 +423,108 @@ public class RequestPartMethodArgumentResolverTests {
 		request.setContentType("multipart/form-data");
 		webRequest = new ServletWebRequest(request);
 
-		Object result = resolver.resolveArgument(optionalPart, null, webRequest, null);
+		Object actualValue = resolver.resolveArgument(optionalPart, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+
+		actualValue = resolver.resolveArgument(optionalPart, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+	}
+
+	@Test
+	public void resolveOptionalPartArgumentWithoutMultipartRequest() throws Exception {
+		webRequest = new ServletWebRequest(new MockHttpServletRequest());
+
+		Object actualValue = resolver.resolveArgument(optionalPart, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+
+		actualValue = resolver.resolveArgument(optionalPart, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+	}
+
+	@Test
+	public void resolveOptionalPartList() throws Exception {
+		MockPart expected = new MockPart("requestPart", "Hello World".getBytes());
+		MockHttpServletRequest request = new MockHttpServletRequest();
+		request.setMethod("POST");
+		request.setContentType("multipart/form-data");
+		request.addPart(expected);
+		request.addPart(new MockPart("otherPart", "Hello World".getBytes()));
+		webRequest = new ServletWebRequest(request);
+
+		Object actualValue = resolver.resolveArgument(optionalPartList, null, webRequest, null);
+		assertTrue(actualValue instanceof Optional);
+		assertEquals("Invalid result", Collections.singletonList(expected), ((Optional) actualValue).get());
+
+		actualValue = resolver.resolveArgument(optionalPartList, null, webRequest, null);
+		assertTrue(actualValue instanceof Optional);
+		assertEquals("Invalid result", Collections.singletonList(expected), ((Optional) actualValue).get());
+	}
+
+	@Test
+	public void resolveOptionalPartListNotPresent() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest();
+		request.setMethod("POST");
+		request.setContentType("multipart/form-data");
+		webRequest = new ServletWebRequest(request);
+
+		Object actualValue = resolver.resolveArgument(optionalPartList, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
 
-		assertTrue(result instanceof Optional);
-		assertFalse("Invalid result", ((Optional) result).isPresent());
+		actualValue = resolver.resolveArgument(optionalPartList, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+	}
+
+	@Test
+	public void resolveOptionalPartListWithoutMultipartRequest() throws Exception {
+		webRequest = new ServletWebRequest(new MockHttpServletRequest());
+
+		Object actualValue = resolver.resolveArgument(optionalPartList, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+
+		actualValue = resolver.resolveArgument(optionalPartList, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
 	}
 
 	@Test
 	public void resolveOptionalRequestPart() throws Exception {
 		SimpleBean simpleBean = new SimpleBean("foo");
-
 		given(messageConverter.canRead(SimpleBean.class, MediaType.TEXT_PLAIN)).willReturn(true);
 		given(messageConverter.read(eq(SimpleBean.class), isA(HttpInputMessage.class))).willReturn(simpleBean);
 
 		ModelAndViewContainer mavContainer = new ModelAndViewContainer();
+
 		Object actualValue = resolver.resolveArgument(optionalRequestPart, mavContainer, webRequest, new ValidatingBinderFactory());
+		assertEquals("Invalid argument value", Optional.of(simpleBean), actualValue);
+		assertFalse("The requestHandled flag shouldn't change", mavContainer.isRequestHandled());
 
+		actualValue = resolver.resolveArgument(optionalRequestPart, mavContainer, webRequest, new ValidatingBinderFactory());
 		assertEquals("Invalid argument value", Optional.of(simpleBean), actualValue);
 		assertFalse("The requestHandled flag shouldn't change", mavContainer.isRequestHandled());
 	}
 
 	@Test
 	public void resolveOptionalRequestPartNotPresent() throws Exception {
-		given(messageConverter.canRead(SimpleBean.class, MediaType.TEXT_PLAIN)).willReturn(true);
-		given(messageConverter.read(eq(SimpleBean.class), isA(RequestPartServletServerHttpRequest.class))).willReturn(null);
+		MockHttpServletRequest request = new MockHttpServletRequest();
+		request.setMethod("POST");
+		request.setContentType("multipart/form-data");
+		webRequest = new ServletWebRequest(request);
 
-		ModelAndViewContainer mavContainer = new ModelAndViewContainer();
-		Object actualValue = resolver.resolveArgument(optionalRequestPart, mavContainer, webRequest, new ValidatingBinderFactory());
+		Object actualValue = resolver.resolveArgument(optionalRequestPart, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
 
+		actualValue = resolver.resolveArgument(optionalRequestPart, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+	}
+
+	@Test
+	public void resolveOptionalRequestPartWithoutMultipartRequest() throws Exception {
+		webRequest = new ServletWebRequest(new MockHttpServletRequest());
+
+		Object actualValue = resolver.resolveArgument(optionalRequestPart, null, webRequest, null);
+		assertEquals("Invalid argument value", Optional.empty(), actualValue);
+
+		actualValue = resolver.resolveArgument(optionalRequestPart, null, webRequest, null);
 		assertEquals("Invalid argument value", Optional.empty(), actualValue);
-		assertFalse("The requestHandled flag shouldn't change", mavContainer.isRequestHandled());
 	}
 
 
@@ -390,8 +533,8 @@ public class RequestPartMethodArgumentResolverTests {
 		given(messageConverter.read(eq(SimpleBean.class), isA(HttpInputMessage.class))).willReturn(argValue);
 
 		ModelAndViewContainer mavContainer = new ModelAndViewContainer();
-		Object actualValue = resolver.resolveArgument(parameter, mavContainer, webRequest, new ValidatingBinderFactory());
 
+		Object actualValue = resolver.resolveArgument(parameter, mavContainer, webRequest, new ValidatingBinderFactory());
 		assertEquals("Invalid argument value", argValue, actualValue);
 		assertFalse("The requestHandled flag shouldn't change", mavContainer.isRequestHandled());
 	}
@@ -425,22 +568,26 @@ public class RequestPartMethodArgumentResolverTests {
 		}
 	}
 
+
 	@SuppressWarnings("unused")
-	public void handle(@RequestPart SimpleBean requestPart,
-					   @RequestPart(value="requestPart", required=false) SimpleBean namedRequestPart,
-					   @Valid @RequestPart("requestPart") SimpleBean validRequestPart,
-					   @RequestPart("requestPart") MultipartFile multipartFile,
-					   @RequestPart("requestPart") List<MultipartFile> multipartFileList,
-					   @RequestPart("requestPart") MultipartFile[] multipartFileArray,
-					   int i,
-					   MultipartFile multipartFileNotAnnot,
-					   Part part,
-					   @RequestPart("part") List<Part> partList,
-					   @RequestPart("part") Part[] partArray,
-					   @RequestParam MultipartFile requestParamAnnot,
-					   Optional<MultipartFile> optionalMultipartFile,
-					   Optional<Part> optionalPart,
-					   @RequestPart("requestPart") Optional<SimpleBean> optionalRequestPart) {
+	public void handle(
+			@RequestPart SimpleBean requestPart,
+			@RequestPart(value="requestPart", required=false) SimpleBean namedRequestPart,
+			@Valid @RequestPart("requestPart") SimpleBean validRequestPart,
+			@RequestPart("requestPart") MultipartFile multipartFile,
+			@RequestPart("requestPart") List<MultipartFile> multipartFileList,
+			@RequestPart("requestPart") MultipartFile[] multipartFileArray,
+			int i,
+			MultipartFile multipartFileNotAnnot,
+			Part part,
+			@RequestPart("requestPart") List<Part> partList,
+			@RequestPart("requestPart") Part[] partArray,
+			@RequestParam MultipartFile requestParamAnnot,
+			Optional<MultipartFile> optionalMultipartFile,
+			@RequestPart("requestPart") Optional<List<MultipartFile>> optionalMultipartFileList,
+			Optional<Part> optionalPart,
+			@RequestPart("requestPart") Optional<List<Part>> optionalPartList,
+			@RequestPart("requestPart") Optional<SimpleBean> optionalRequestPart) {
 	}
 
 }

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/support/DefaultHandlerExceptionResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 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.
@@ -47,7 +47,9 @@ import org.springframework.web.servlet.mvc.multiaction.NoSuchRequestHandlingMeth
 
 import static org.junit.Assert.*;
 
-/** @author Arjen Poutsma */
+/**
+ * @author Arjen Poutsma
+ */
 public class DefaultHandlerExceptionResolverTests {
 
 	private DefaultHandlerExceptionResolver exceptionResolver;
@@ -174,7 +176,9 @@ public class DefaultHandlerExceptionResolverTests {
 		assertNotNull("No ModelAndView returned", mav);
 		assertTrue("No Empty ModelAndView returned", mav.isEmpty());
 		assertEquals("Invalid status code", 400, response.getStatus());
-		assertEquals("Required request part 'name' is not present.", response.getErrorMessage());
+		assertTrue(response.getErrorMessage().contains("request part"));
+		assertTrue(response.getErrorMessage().contains("name"));
+		assertTrue(response.getErrorMessage().contains("not present"));
 	}
 
 	@Test
@@ -211,6 +215,7 @@ public class DefaultHandlerExceptionResolverTests {
 		assertSame(ex, request.getAttribute("javax.servlet.error.exception"));
 	}
 
+
 	@SuppressWarnings("unused")
 	public void handle(String arg) {
 	}