#340 - Polishing.

Moved AffordanceModelFactory into core package as it's SPI. Switched to Spring Factories lookup of implementation classes so that we avoid a package dependency between the MVC package and the media type specific packages. Removed reference to MediaType from AffordanceModelFactory to AffordanceModel so that a factory can even provide models for different MediaTypes (i.e. different flavors of the same one, e.g. HAL Forms for JSON and XML). Also removed addAffordanceModel(…) from Affordance to not force the implementations into mutability. Made most of the affordance building API types package protected. HalFormsAffordanceModel now uses MethodParameters abstraction to simplify model parsing code.

Tweaked HAL forms model to work with factory methods for required properties and wither methods to add optional properties. Tweaked and inlined mixin types in Jackson module for HAL forms.

Slight API polishing on Link to make sure Affordance collecting methods are not named with….

Tweaked Lombok setup to use all caps for logger constants. Removed deprecation warnings in Jackson2HalModule.

Author: odrotbohm

lombok.config

@@ -0,0 +1,3 @@
+lombok.anyConstructor.suppressConstructorProperties=true
+lombok.nonNull.exceptionType = IllegalArgumentException
+lombok.log.fieldName = LOG

src/main/java/org/springframework/hateoas/Affordance.java

@@ -15,12 +15,14 @@
  */
 package org.springframework.hateoas;
 
+import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
 
 /**
  * Abstract representation of an action a link is able to take. Web frameworks must provide concrete implementation.
  *
  * @author Greg Turnquist
+ * @author Oliver Gierke
  */
 public interface Affordance {
 
@@ -29,7 +31,7 @@ public interface Affordance {
 	 *
 	 * @return
 	 */
-	String getHttpMethod();
+	HttpMethod getHttpMethod();
 
 	/**
 	 * Name for the REST action this {@link Affordance} can take.
@@ -44,14 +46,5 @@ public interface Affordance {
 	 * @param mediaType
 	 * @return
 	 */
-	AffordanceModel getAffordanceModel(MediaType mediaType);
-
-	/**
-	 * Add a new {@link AffordanceModel} for a given {@link MediaType}.
-	 *
-	 * @param mediaType
-	 * @param affordanceModel
-	 */
-	void addAffordanceModel(MediaType mediaType, AffordanceModel affordanceModel);
-
+	<T extends AffordanceModel> T getAffordanceModel(MediaType mediaType);
 }

src/main/java/org/springframework/hateoas/AffordanceModel.java

@@ -15,11 +15,23 @@
  */
 package org.springframework.hateoas;
 
+import java.util.Collection;
+
+import org.springframework.http.MediaType;
+
 /**
- * Marker interface for mediatypes to build up type-specific details for an {@link Affordance}
+ * An affordance model is a media type specific description of an affordance.
  * 
  * @author Greg Turnquist
+ * @author Oliver Gierke
  */
 public interface AffordanceModel {
 
+	/**
+	 * The media types this is a model for. Can be multiple ones as often media types come in different flavors like an
+	 * XML and JSON one and in simple cases a single model might serve them all.
+	 * 
+	 * @return will never be {@literal null}.
+	 */
+	Collection<MediaType> getMediaTypes();
 }

src/main/java/org/springframework/hateoas/Link.java

@@ -34,12 +34,12 @@
 import javax.xml.bind.annotation.XmlTransient;
 import javax.xml.bind.annotation.XmlType;
 
-import org.springframework.hateoas.core.LinkBuilderSupport;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonInclude;
 
 /**
  * Value object for links.
@@ -48,6 +48,7 @@
  * @author Greg Turnquist
  */
 @XmlType(name = "link", namespace = Link.ATOM_NAMESPACE)
+@JsonInclude(JsonInclude.Include.NON_NULL)
 @JsonIgnoreProperties("templated")
 @AllArgsConstructor(access = AccessLevel.PACKAGE)
 @Getter
@@ -113,11 +114,11 @@ public Link(UriTemplate template, String rel) {
 	}
 
 	public Link(String href, String rel, List<Affordance> affordances) {
-		
+
 		this(href, rel);
 
 		Assert.notNull(affordances, "affordances must not be null!");
-		
+
 		this.affordances = affordances;
 	}
 
@@ -134,7 +135,7 @@ protected Link() {
 	 * @return
 	 */
 	public List<Affordance> getAffordances() {
-		return new ArrayList<Affordance>(Collections.unmodifiableCollection(this.affordances));
+		return Collections.unmodifiableList(this.affordances);
 	}
 
 	/**
@@ -149,35 +150,46 @@ public Link withSelfRel() {
 	/**
 	 * Create new {@link Link} with an additional {@link Affordance}.
 	 *
-	 * @param affordance
+	 * @param affordance must not be {@literal null}.
 	 * @return
 	 */
-	public Link withAffordance(Affordance affordance) {
+	public Link andAffordance(Affordance affordance) {
+
+		Assert.notNull(affordance, "Affordance must not be null!");
 
 		List<Affordance> newAffordances = new ArrayList<Affordance>();
 		newAffordances.addAll(this.affordances);
 		newAffordances.add(affordance);
 
-		return new Link(this.rel, this.href, this.hreflang ,this.media, this.title, this.type,
-			this.deprecation, this.template, newAffordances);
+		return withAffordances(newAffordances);
 	}
 
 	/**
 	 * Create new {@link Link} with additional {@link Affordance}s.
 	 * 
-	 * @param affordances
+	 * @param affordances must not be {@literal null}.
 	 * @return
 	 */
-	public Link addAffordances(List<Affordance> affordances) {
+	public Link andAffordances(List<Affordance> affordances) {
 
 		List<Affordance> newAffordances = new ArrayList<Affordance>();
 		newAffordances.addAll(this.affordances);
 		newAffordances.addAll(affordances);
 
-		return new Link(this.rel, this.href, this.hreflang ,this.media, this.title, this.type,
-			this.deprecation, this.template, newAffordances);
+		return withAffordances(newAffordances);
 	}
 
+	/**
+	 * Creats a new {@link Link} with the given {@link Affordance}s.
+	 * 
+	 * @param affordances must not be {@literal null}.
+	 * @return
+	 */
+	public Link withAffordances(List<Affordance> affordances) {
+
+		return new Link(this.rel, this.href, this.hreflang, this.media, this.title, this.type, this.deprecation,
+				this.template, affordances);
+	}
 
 	/**
 	 * Returns the variable names contained in the template.

src/main/java/org/springframework/hateoas/config/EnableHypermediaSupport.java

@@ -15,6 +15,8 @@
  */
 package org.springframework.hateoas.config;
 
+import lombok.extern.slf4j.Slf4j;
+
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
@@ -25,8 +27,6 @@
 import java.util.List;
 import java.util.Map;
 
-import lombok.extern.slf4j.Slf4j;
-
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Import;
 import org.springframework.context.annotation.ImportSelector;
@@ -54,7 +54,7 @@
 @Target(ElementType.TYPE)
 @Documented
 @Import({ HypermediaSupportBeanDefinitionRegistrar.class, HateoasConfiguration.class,
-	EnableHypermediaSupport.HypermediaConfigurationImportSelector.class})
+		EnableHypermediaSupport.HypermediaConfigurationImportSelector.class })
 public @interface EnableHypermediaSupport {
 
 	/**
@@ -68,6 +68,7 @@
 	 * Hypermedia representation types supported.
 	 * 
 	 * @author Oliver Gierke
+	 * @author Greg Turnquist
 	 */
 	enum HypermediaType {
 
@@ -81,6 +82,7 @@ enum HypermediaType {
 
 		/**
 		 * HAL-FORMS - Independent, backward-compatible extension of the HAL designed to add runtime FORM support
+		 * 
 		 * @see https://rwcbook.github.io/hal-forms/
 		 */
 		HAL_FORMS(HalFormsWebMvcConfigurer.class);
@@ -109,8 +111,8 @@ public String[] selectImports(AnnotationMetadata metadata) {
 				types = HypermediaType.values();
 			}
 
-			log.debug("Registering support for hypermedia types {} according to configuration on {}",
-				types, metadata.getClassName());
+			LOG.debug("Registering support for hypermedia types {} according to configuration on {}", types,
+					metadata.getClassName());
 
 			List<String> configurationNames = new ArrayList<String>();
 

src/main/java/org/springframework/hateoas/config/HypermediaSupportBeanDefinitionRegistrar.java

@@ -86,7 +86,6 @@ class HypermediaSupportBeanDefinitionRegistrar implements ImportBeanDefinitionRe
 
 	private static final String DELEGATING_REL_PROVIDER_BEAN_NAME = "_relProvider";
 	private static final String LINK_DISCOVERER_REGISTRY_BEAN_NAME = "_linkDiscovererRegistry";
-	private static final String AFFORDANCE_MODEL_FACTORY_REGISTRY_BEAN_NAME = "_affordanceModelFactoryRegistry";
 	private static final String HAL_OBJECT_MAPPER_BEAN_NAME = "_halObjectMapper";
 	private static final String HAL_FORMS_OBJECT_MAPPER_BEAN_NAME = "_halFormsObjectMapper";
 	private static final String MESSAGE_SOURCE_BEAN_NAME = "linkRelationMessageSource";
@@ -146,7 +145,8 @@ public void registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionR
 		registerRelProviderPluginRegistryAndDelegate(registry);
 	}
 
-	private static void registerHypermediaComponents(AnnotationMetadata metadata, BeanDefinitionRegistry registry, String objectMapperBeanName) {
+	private static void registerHypermediaComponents(AnnotationMetadata metadata, BeanDefinitionRegistry registry,
+			String objectMapperBeanName) {
 
 		if (JACKSON2_PRESENT) {
 
@@ -316,7 +316,7 @@ private List<HttpMessageConverter<?>> potentiallyRegisterModule(List<HttpMessage
 
 				ObjectMapper halObjectMapper = beanFactory.getBean(HAL_OBJECT_MAPPER_BEAN_NAME, ObjectMapper.class);
 				MessageSourceAccessor linkRelationMessageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME,
-					MessageSourceAccessor.class);
+						MessageSourceAccessor.class);
 
 				halObjectMapper.registerModule(new Jackson2HalModule());
 
@@ -340,7 +340,7 @@ private List<HttpMessageConverter<?>> potentiallyRegisterModule(List<HttpMessage
 
 				ObjectMapper halFormsObjectMapper = beanFactory.getBean(HAL_FORMS_OBJECT_MAPPER_BEAN_NAME, ObjectMapper.class);
 				MessageSourceAccessor linkRelationMessageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME,
-					MessageSourceAccessor.class);
+						MessageSourceAccessor.class);
 
 				halFormsObjectMapper.registerModule(new Jackson2HalFormsModule());
 
@@ -354,7 +354,7 @@ private List<HttpMessageConverter<?>> potentiallyRegisterModule(List<HttpMessage
 				}
 
 				MappingJackson2HttpMessageConverter halFormsConverter = new TypeConstrainedMappingJackson2HttpMessageConverter(
-					ResourceSupport.class);
+						ResourceSupport.class);
 				halFormsConverter.setSupportedMediaTypes(Arrays.asList(HAL_FORMS_JSON));
 				halFormsConverter.setObjectMapper(halFormsObjectMapper);
 				result.add(halFormsConverter);

src/main/java/org/springframework/hateoas/AffordanceModelFactory.java renamed to src/main/java/org/springframework/hateoas/core/AffordanceModelFactory.java

@@ -13,8 +13,10 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.springframework.hateoas;
+package org.springframework.hateoas.core;
 
+import org.springframework.hateoas.Affordance;
+import org.springframework.hateoas.AffordanceModel;
 import org.springframework.hateoas.core.DummyInvocationUtils.MethodInvocation;
 import org.springframework.http.MediaType;
 import org.springframework.plugin.core.Plugin;
@@ -24,15 +26,9 @@
  * TODO: Replace this with an interface and a default implementation of {@link #supports(MediaType)} in Java 8.
  * 
  * @author Greg Turnquist
+ * @author Oliver Gierke
  */
-public abstract class AffordanceModelFactory implements Plugin<MediaType> {
-
-	/**
-	 * Look up the {@link MediaType} of this factory.
-	 *
-	 * @return
-	 */
-	abstract public MediaType getMediaType();
+public interface AffordanceModelFactory extends Plugin<MediaType> {
 
 	/**
 	 * Look up the {@link AffordanceModel} for this factory.
@@ -42,16 +38,5 @@ public abstract class AffordanceModelFactory implements Plugin<MediaType> {
 	 * @param components
 	 * @return
 	 */
-	abstract public AffordanceModel getAffordanceModel(Affordance affordance, MethodInvocation invocationValue, UriComponents components);
-
-	/**
-	 * Find factories based on {@link MediaType}.
-	 * 
-	 * @param delimiter
-	 * @return
-	 */
-	@Override
-	public boolean supports(MediaType delimiter) {
-		return delimiter != null && delimiter.equals(this.getMediaType());
-	}
+	AffordanceModel getAffordanceModel(Affordance affordance, MethodInvocation invocationValue, UriComponents components);
 }

src/main/java/org/springframework/hateoas/core/AnnotationMappingDiscoverer.java

@@ -21,9 +21,11 @@
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.regex.Pattern;
 
+import org.springframework.http.HttpMethod;
 import org.springframework.util.Assert;
 import org.springframework.web.bind.annotation.RequestMethod;
 
@@ -111,15 +113,15 @@ public String getMapping(Class<?> type, Method method) {
 	}
 
 	/**
-	 * Extract {@link org.springframework.web.bind.annotation.RequestMapping}'s list of {@link RequestMethod}s
-	 * into an array of {@link String}s.
+	 * Extract {@link org.springframework.web.bind.annotation.RequestMapping}'s list of {@link RequestMethod}s into an
+	 * array of {@link String}s.
 	 * 
 	 * @param type
 	 * @param method
 	 * @return
 	 */
 	@Override
-	public String[] getRequestType(Class<?> type, Method method) {
+	public Collection<HttpMethod> getRequestMethod(Class<?> type, Method method) {
 
 		Assert.notNull(type, "Type must not be null!");
 		Assert.notNull(method, "Method must not be null!");
@@ -129,13 +131,13 @@ public String[] getRequestType(Class<?> type, Method method) {
 
 		RequestMethod[] requestMethods = (RequestMethod[]) value;
 
-		List<String> requestMethodNames = new ArrayList<String>();
+		List<HttpMethod> requestMethodNames = new ArrayList<HttpMethod>();
 
 		for (RequestMethod requestMethod : requestMethods) {
-			requestMethodNames.add(requestMethod.toString());
+			requestMethodNames.add(HttpMethod.valueOf(requestMethod.toString()));
 		}
 
-		return requestMethodNames.toArray(new String[]{});
+		return requestMethodNames;
 	}
 
 	private String[] getMappingFrom(Annotation annotation) {