Fix resource-chain XML syntax for cache

This change moves the resource-cache configuration to the
<resource-chain/> tag, since enabling/disabling resource cache should
be driven by a property or a SpEL expression.

So now that configuration can be set with XML attributes:

  <mvc:resource-chain resource-cache="true"
  cache-manager="resourceCache" cache-name="test-resource-cache">

In order to mirror the JavaConfig behavior, the "resource-cache"
attribute is required.

Issue: SPR-12129

spring-webmvc/src/main/java/org/springframework/web/servlet/config/ResourcesBeanDefinitionParser.java

@@ -200,8 +200,8 @@ class ResourcesBeanDefinitionParser implements BeanDefinitionParser {
 	private void parseResourceCache(ManagedList<? super Object> resourceResolvers,
 			ManagedList<? super Object> resourceTransformers, Element element, Object source) {
 
-		Element resourceCacheElement = DomUtils.getChildElementByTagName(element, "resource-cache");
-		if (resourceCacheElement != null) {
+		String resourceCache = element.getAttribute("resource-cache");
+		if ("true".equals(resourceCache)) {
 			ConstructorArgumentValues cavs = new ConstructorArgumentValues();
 
 			RootBeanDefinition cachingResolverDef = new RootBeanDefinition(CachingResourceResolver.class);
@@ -214,8 +214,8 @@ class ResourcesBeanDefinitionParser implements BeanDefinitionParser {
 			cachingTransformerDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
 			cachingTransformerDef.setConstructorArgumentValues(cavs);
 
-			String cacheManagerName = resourceCacheElement.getAttribute("cache-manager");
-			String cacheName = resourceCacheElement.getAttribute("cache-name");
+			String cacheManagerName = element.getAttribute("cache-manager");
+			String cacheName = element.getAttribute("cache-name");
 			if (StringUtils.hasText(cacheManagerName) && StringUtils.hasText(cacheName)) {
 				RuntimeBeanReference cacheManagerRef = new RuntimeBeanReference(cacheManagerName);
 				cavs.addIndexedArgumentValue(0, cacheManagerRef);

spring-webmvc/src/main/java/org/springframework/web/servlet/config/annotation/ResourceHandlerRegistration.java

@@ -99,7 +99,7 @@ public class ResourceHandlerRegistration {
 	 *
 	 * @param cacheResources whether to cache the result of resource resolution;
 	 * 		setting this to "true" is recommended for production (and "false" for
-	 * 	    development, especially when applying a version strategy.
+	 * 	    development, especially when applying a version strategy).
 	 * @return the same {@link ResourceHandlerRegistration} instance for chained method invocation
 	 * @since 4.1
 	 */

spring-webmvc/src/main/resources/org/springframework/web/servlet/config/spring-mvc-4.1.xsd

@@ -338,18 +338,6 @@
 		</xsd:complexType>
 	</xsd:element>
 
-	<xsd:complexType name="resource-cache">
-		<xsd:annotation>
-			<xsd:documentation source="org.springframework.web.servlet.resource.CachingResourceResolver"><![CDATA[
-	A ResourceResolver that resolves resources from a Cache or otherwise delegates to the resolver chain
-	and saves the result in the cache. Can use a custom Cache if a CacheManager is provided as a bean reference
-	in the "cache-manager" attribute, and the cache name provided in the "cache-name" attribute.
-			]]></xsd:documentation>
-		</xsd:annotation>
-		<xsd:attribute name="cache-manager" type="xsd:string" use="optional"/>
-		<xsd:attribute name="cache-name" type="xsd:string" use="optional"/>
-	</xsd:complexType>
-
 	<xsd:complexType name="content-version-strategy">
 		<xsd:annotation>
 			<xsd:documentation source="org.springframework.web.servlet.resource.ContentVersionStrategy"><![CDATA[
@@ -471,16 +459,22 @@
 		<xsd:annotation>
 			<xsd:documentation source="org.springframework.web.servlet.config.annotation.ResourceChainRegistration"><![CDATA[
 	Assists with the registration of resource resolvers and transformers.
-	Unless set to "false", the auto-registration add default Resolvers (a PathResourceResolver) and Transformers
+	Unless set to "false", the auto-registration adds default Resolvers (a PathResourceResolver) and Transformers
 	(CssLinkResourceTransformer, if a VersionResourceResolver has been manually registered).
+	The resource-cache attribute sets whether to cache the result of resource resolution/transformation;
+	setting this to "true" is recommended for production (and "false" for development).
+	A custom Cache can be configured if a CacheManager is provided as a bean reference
+	in the "cache-manager" attribute, and the cache name provided in the "cache-name" attribute.
 			]]></xsd:documentation>
 		</xsd:annotation>
 		<xsd:sequence>
-			<xsd:element name="resource-cache" type="resource-cache" minOccurs="0" maxOccurs="1"/>
 			<xsd:element name="resolvers" type="resource-resolvers" minOccurs="0" maxOccurs="1"/>
 			<xsd:element name="transformers" type="resource-transformers" minOccurs="0" maxOccurs="1"/>
 		</xsd:sequence>
+		<xsd:attribute name="resource-cache" type="xsd:boolean" use="required"/>
 		<xsd:attribute name="auto-registration" type="xsd:boolean" default="true" use="optional"/>
+		<xsd:attribute name="cache-manager" type="xsd:string" use="optional"/>
+		<xsd:attribute name="cache-name" type="xsd:string" use="optional"/>
 	</xsd:complexType>
 
 	<xsd:element name="resources">

spring-webmvc/src/test/resources/org/springframework/web/servlet/config/mvc-config-resources-chain-no-auto.xml

@@ -6,7 +6,7 @@
 		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
 
 	<mvc:resources mapping="/resources/**" location="/, classpath:/META-INF/">
-		<mvc:resource-chain auto-registration="false">
+		<mvc:resource-chain resource-cache="false" auto-registration="false">
 			<mvc:resolvers>
 				<mvc:version-resolver>
 					<mvc:fixed-version-strategy version="abc" patterns="/**/*.js"/>

spring-webmvc/src/test/resources/org/springframework/web/servlet/config/mvc-config-resources-chain.xml

@@ -22,8 +22,7 @@
 		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">
 
 	<mvc:resources mapping="/resources/**" location="/, classpath:/META-INF/">
-		<mvc:resource-chain>
-			<mvc:resource-cache cache-manager="resourceCache" cache-name="test-resource-cache"/>
+		<mvc:resource-chain resource-cache="true" cache-manager="resourceCache" cache-name="test-resource-cache">
 			<mvc:resolvers>
 				<mvc:version-resolver>
 					<mvc:fixed-version-strategy version="abc" patterns="/**/*.js"/>