Added provider interface for relation types by entity type.

Author: odrotbohm

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(Class<?> type);
+
+	String getRelForSingleResource(Class<?> type);
+}

src/main/java/org/springframework/hateoas/mvc/ControllerRelProvider.java

@@ -0,0 +1,60 @@
+/*
+ * 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.mvc;
+
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.hateoas.ExposesResourceFor;
+import org.springframework.hateoas.RelProvider;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+/**
+ * @author Oliver Gierke
+ */
+public class ControllerRelProvider implements RelProvider {
+
+	private final Class<?> entityType;
+	private final String collectionResourceRel;
+	private final String singleResourceRel;
+
+	public ControllerRelProvider(Class<?> controller) {
+
+		ExposesResourceFor annotation = AnnotationUtils.findAnnotation(controller, ExposesResourceFor.class);
+		Assert.notNull(annotation);
+
+		this.entityType = annotation.value();
+		this.singleResourceRel = StringUtils.uncapitalize(entityType.getSimpleName());
+		this.collectionResourceRel = singleResourceRel + "List";
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.RelProvider#getRelForCollectionResource(java.lang.Class)
+	 */
+	@Override
+	public String getRelForCollectionResource(Class<?> type) {
+		return collectionResourceRel;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.RelProvider#getRelForSingleResource(java.lang.Class)
+	 */
+	@Override
+	public String getRelForSingleResource(Class<?> type) {
+		return singleResourceRel;
+	}
+}