Hal 47: additional hal-support for spring-hateoas

.gitignore

@@ -1,4 +1,5 @@
 target/
+test-output/
 .settings/
 .project
 .classpath

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

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2013 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.hateoas;
+
+/**
+ * @author Oliver Gierke
+ */
+public interface RelProvider {
+
+	String getRelForCollectionResource(Object type);
+
+	String getRelForSingleResource(Object type);
+}

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

@@ -15,7 +15,8 @@
  */
 package org.springframework.hateoas.config;
 
-import static org.springframework.beans.factory.support.BeanDefinitionReaderUtils.*;
+import static org.springframework.beans.factory.support.BeanDefinitionReaderUtils.registerBeanDefinition;
+import static org.springframework.beans.factory.support.BeanDefinitionReaderUtils.registerWithGeneratedName;
 
 import java.util.List;
 import java.util.Map;
@@ -103,12 +104,12 @@ private AbstractBeanDefinition getLinkDiscovererBeanDefinition(HypermediaType ty
 		AbstractBeanDefinition definition;
 
 		switch (type) {
-			case HAL:
-				definition = new RootBeanDefinition(HalLinkDiscoverer.class);
-				break;
-			case DEFAULT:
-			default:
-				definition = new RootBeanDefinition(DefaultLinkDiscoverer.class);
+		case HAL:
+			definition = new RootBeanDefinition(HalLinkDiscoverer.class);
+			break;
+		case DEFAULT:
+		default:
+			definition = new RootBeanDefinition(DefaultLinkDiscoverer.class);
 		}
 
 		definition.setSource(this);

src/main/java/org/springframework/hateoas/hal/AnnotationRelProvider.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2013 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.hateoas.hal;
+
+import org.springframework.hateoas.RelProvider;
+import org.springframework.hateoas.Resource;
+
+/**
+ * @author Oliver Gierke
+ */
+public class AnnotationRelProvider implements RelProvider {
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.RelProvider#getRelForCollectionResource(java.lang.Object)
+	 */
+	@Override
+	public String getRelForCollectionResource(Object resource) {
+		// check for hateoas wrapper type
+		if (Resource.class.isInstance(resource)) {
+			resource = ((Resource) resource).getContent();
+		}
+
+		HalRelation annotation = resource.getClass().getAnnotation(HalRelation.class);
+		if (annotation == null || HalRelation.NO_RELATION.equals(annotation.collectionRelation())) {
+			return null;
+		}
+		return annotation.value();
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.RelProvider#getRelForSingleResource(java.lang.Object)
+	 */
+	@Override
+	public String getRelForSingleResource(Object resource) {
+		// check for hateoas wrapper type
+		if (Resource.class.isInstance(resource)) {
+			resource = ((Resource) resource).getContent();
+		}
+
+		HalRelation annotation = resource.getClass().getAnnotation(HalRelation.class);
+		if (annotation == null || HalRelation.NO_RELATION.equals(annotation.value())) {
+			return null;
+		}
+		return annotation.value();
+	}
+}

src/main/java/org/springframework/hateoas/hal/HalRelation.java

@@ -0,0 +1,18 @@
+package org.springframework.hateoas.hal;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ ElementType.TYPE, ElementType.FIELD, ElementType.METHOD, ElementType.ANNOTATION_TYPE })
+@Retention(RetentionPolicy.RUNTIME)
+public @interface HalRelation {
+
+	public static final String NO_RELATION = "";
+
+	String value() default NO_RELATION;
+
+	String collectionRelation() default NO_RELATION;
+
+}