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 {
+
+}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestResponseBodyMethodProcessor.java

@@ -81,7 +81,8 @@ public class RequestResponseBodyMethodProcessor extends AbstractMessageConverter
 
 	@Override
 	public boolean supportsReturnType(MethodParameter returnType) {
-		return returnType.getMethodAnnotation(ResponseBody.class) != null;
+		return ((AnnotationUtils.findAnnotation(returnType.getDeclaringClass(), ResponseBody.class) != null)
+				|| (returnType.getMethodAnnotation(ResponseBody.class) != null));
 	}
 
 	/**

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/RequestResponseBodyMethodProcessorTests.java

@@ -16,9 +16,6 @@
 
 package org.springframework.web.servlet.mvc.method.annotation;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-
 import java.io.Serializable;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
@@ -39,12 +36,17 @@ import org.springframework.util.MultiValueMap;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.bind.support.WebDataBinderFactory;
 import org.springframework.web.context.request.NativeWebRequest;
 import org.springframework.web.context.request.ServletWebRequest;
 import org.springframework.web.method.HandlerMethod;
 import org.springframework.web.method.support.ModelAndViewContainer;
 
+import static org.junit.Assert.*;
+
 /**
  * Test fixture for a {@link RequestResponseBodyMethodProcessor} with actual delegation
  * to HttpMessageConverter instances.
@@ -231,6 +233,34 @@ public class RequestResponseBodyMethodProcessorTests {
 		assertEquals("text/plain;charset=UTF-8", servletResponse.getHeader("Content-Type"));
 	}
 
+	@Test
+	public void supportsReturnTypeResponseBodyOnType() throws Exception {
+
+		Method method = ResponseBodyController.class.getMethod("handle");
+		MethodParameter returnType = new MethodParameter(method, -1);
+
+		List<HttpMessageConverter<?>> converters = new ArrayList<HttpMessageConverter<?>>();
+		converters.add(new StringHttpMessageConverter());
+
+		RequestResponseBodyMethodProcessor processor = new RequestResponseBodyMethodProcessor(converters);
+
+		assertTrue("Failed to recognize type-level @ResponseBody", processor.supportsReturnType(returnType));
+	}
+
+	@Test
+	public void supportsReturnTypeRestController() throws Exception {
+
+		Method method = TestRestController.class.getMethod("handle");
+		MethodParameter returnType = new MethodParameter(method, -1);
+
+		List<HttpMessageConverter<?>> converters = new ArrayList<HttpMessageConverter<?>>();
+		converters.add(new StringHttpMessageConverter());
+
+		RequestResponseBodyMethodProcessor processor = new RequestResponseBodyMethodProcessor(converters);
+
+		assertTrue("Failed to recognize type-level @RestController", processor.supportsReturnType(returnType));
+	}
+
 
 	public String handle(
 			@RequestBody List<SimpleBean> list,
@@ -289,4 +319,22 @@ public class RequestResponseBodyMethodProcessorTests {
 		}
 	}
 
+	@ResponseBody
+	private static class ResponseBodyController {
+
+		@RequestMapping
+		public String handle() {
+			return "hello";
+		}
+	}
+
+	@RestController
+	private static class TestRestController {
+
+		@RequestMapping
+		public String handle() {
+			return "hello";
+		}
+	}
+
 }

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ServletAnnotationControllerHandlerMethodTests.java

@@ -16,14 +16,6 @@
 
 package org.springframework.web.servlet.mvc.method.annotation;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
-
 import java.beans.PropertyEditorSupport;
 import java.io.IOException;
 import java.io.Serializable;
@@ -64,10 +56,6 @@ import org.junit.Test;
 import org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator;
 import org.springframework.aop.interceptor.SimpleTraceInterceptor;
 import org.springframework.aop.support.DefaultPointcutAdvisor;
-import org.springframework.tests.sample.beans.DerivedTestBean;
-import org.springframework.tests.sample.beans.GenericBean;
-import org.springframework.tests.sample.beans.ITestBean;
-import org.springframework.tests.sample.beans.TestBean;
 import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
@@ -101,6 +89,10 @@ import org.springframework.mock.web.test.MockServletConfig;
 import org.springframework.mock.web.test.MockServletContext;
 import org.springframework.oxm.jaxb.Jaxb2Marshaller;
 import org.springframework.stereotype.Controller;
+import org.springframework.tests.sample.beans.DerivedTestBean;
+import org.springframework.tests.sample.beans.GenericBean;
+import org.springframework.tests.sample.beans.ITestBean;
+import org.springframework.tests.sample.beans.TestBean;
 import org.springframework.ui.ExtendedModelMap;
 import org.springframework.ui.Model;
 import org.springframework.ui.ModelMap;
@@ -123,6 +115,7 @@ import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.bind.annotation.SessionAttributes;
 import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
 import org.springframework.web.bind.support.WebArgumentResolver;
@@ -142,6 +135,8 @@ import org.springframework.web.servlet.mvc.support.RedirectAttributes;
 import org.springframework.web.servlet.support.RequestContextUtils;
 import org.springframework.web.servlet.view.InternalResourceViewResolver;
 
+import static org.junit.Assert.*;
+
 /**
  * The origin of this test class is {@link ServletAnnotationControllerHandlerMethodTests}.
  *
@@ -1569,6 +1564,18 @@ public class ServletAnnotationControllerHandlerMethodTests extends AbstractServl
 		assertEquals("count:3", response.getContentAsString());
 	}
 
+	@Test
+	public void restController() throws Exception {
+
+		initServletWithControllers(ThisWillActuallyRun.class);
+
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/");
+		MockHttpServletResponse response = new MockHttpServletResponse();
+		getServlet().service(request, response);
+		assertEquals("Hello World!", response.getContentAsString());
+	}
+
+
 	/*
 	 * Controllers
 	 */
@@ -2979,6 +2986,16 @@ public class ServletAnnotationControllerHandlerMethodTests extends AbstractServl
 		}
 	}
 
+	@RestController
+	static class ThisWillActuallyRun {
+
+		@RequestMapping(value = "/", method = RequestMethod.GET)
+		public String home() {
+			return "Hello World!";
+		}
+	}
+
+
 // Test cases deleted from the original SevletAnnotationControllerTests:
 
 //	@Ignore("Controller interface => no method-level @RequestMapping annotation")