Allow @ResponseBody on the type level

This change enables having @ResponseBody on the type-level in which
case it inherited and does not need to be added on the method level.

For added convenience, there is also a new @RestController annotation,
a meta-annotation in turn annotated with @Controller and @ResponseBody.
Classes with the new annotation do not need to have @ResponseBody
declared on the method level as it is inherited.

Issue: SPR-10814

spring-web/src/main/java/org/springframework/web/bind/annotation/ResponseBody.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2013 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.
@@ -23,15 +23,18 @@ import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
 /**
- * Annotation which indicates that a method return value should be bound to the web response body.
- * Supported for annotated handler methods in Servlet environments.
+ * Annotation that indicates a method return value should be bound to the web response
+ * body. Supported for annotated handler methods in Servlet environments.
+ * <p>
+ * As of version 4.0 this annotation can also be added on the type level in which case
+ * is inherited and does not need to be added on the method level.
  *
  * @author Arjen Poutsma
  * @since 3.0
  * @see RequestBody
- * @see org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter
+ * @see RestController
  */
-@Target(ElementType.METHOD)
+@Target({ElementType.TYPE, ElementType.METHOD})
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
 public @interface ResponseBody {

spring-web/src/main/java/org/springframework/web/bind/annotation/RestController.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2002-2012 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.bind.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.stereotype.Controller;
+
+/**
+ * A convenience annotation that is itself annotated with {@link Controller @Controller}
+ * and {@link ResponseBody @ResponseBody}.
+ * <p>
+ * Types that carry this annotation are treated as
+ * controllers where {@link RequestMapping @RequestMapping} methods assume
+ * {@link ResponseBody @ResponseBody} semantics by default.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.0
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Controller
+@ResponseBody
+public @interface RestController {
+
+}