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-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")