Fix issue with DeferredResult on @RestController

Before this change, async result handling on controller methods failed
to observe type-level annotations annotations. The issue was never
noticed until we started supporting type-level @ResponseBody and the
@RestController meta annotation.

Issue: SPR-10905

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

@@ -174,9 +174,10 @@ public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
 	}
 
 	/**
-	 * Return a ServletInvocableHandlerMethod that will process the value returned
-	 * from an async operation essentially either applying return value handling or
-	 * raising an exception if the end result is an Exception.
+	 * Create a ServletInvocableHandlerMethod that will return the given value from an
+	 * async operation instead of invoking the controller method again. The async result
+	 * value is then either processed as if the controller method returned it or an
+	 * exception is raised if the async result value itself is an Exception.
 	 */
 	ServletInvocableHandlerMethod wrapConcurrentResult(final Object result) {
 
@@ -197,9 +198,12 @@ public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
 
 
 	/**
-	 * A ServletInvocableHandlerMethod sub-class that invokes a given
-	 * {@link Callable} and "inherits" the annotations of the containing class
-	 * instance, useful for invoking a Callable returned from a HandlerMethod.
+	 * A sub-class of {@link HandlerMethod} that invokes the given {@link Callable}
+	 * instead of the target controller method. This is useful for resuming processing
+	 * with the result of an async operation. The goal is to process the value returned
+	 * from the Callable as if it was returned by the target controller method, i.e.
+	 * taking into consideration both method and type-level controller annotations (e.g.
+	 * {@code @ResponseBody}, {@code @ResponseStatus}, etc).
 	 */
 	private class CallableHandlerMethod extends ServletInvocableHandlerMethod {
 
@@ -208,6 +212,17 @@ public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
 			this.setHandlerMethodReturnValueHandlers(ServletInvocableHandlerMethod.this.returnValueHandlers);
 		}
 
+		/**
+		 * Bridge to type-level annotations of the target controller method.
+		 */
+		@Override
+		public Class<?> getBeanType() {
+			return ServletInvocableHandlerMethod.this.getBeanType();
+		}
+
+		/**
+		 * Bridge to method-level annotations of the target controller method.
+		 */
 		@Override
 		public <A extends Annotation> A getMethodAnnotation(Class<A> annotationType) {
 			return ServletInvocableHandlerMethod.this.getMethodAnnotation(annotationType);

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

@@ -15,12 +15,9 @@
  */
 
 package org.springframework.web.servlet.mvc.method.annotation;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
-
 import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.List;
 
 import javax.servlet.http.HttpServletResponse;
 
@@ -28,13 +25,18 @@ import org.junit.Before;
 import org.junit.Test;
 import org.springframework.core.MethodParameter;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.HttpMessageNotWritableException;
+import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.mock.web.test.MockHttpServletRequest;
 import org.springframework.mock.web.test.MockHttpServletResponse;
 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.context.request.NativeWebRequest;
 import org.springframework.web.context.request.ServletWebRequest;
+import org.springframework.web.context.request.async.DeferredResult;
 import org.springframework.web.method.annotation.RequestParamMethodArgumentResolver;
 import org.springframework.web.method.support.HandlerMethodArgumentResolverComposite;
 import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
@@ -42,6 +44,8 @@ import org.springframework.web.method.support.HandlerMethodReturnValueHandlerCom
 import org.springframework.web.method.support.ModelAndViewContainer;
 import org.springframework.web.servlet.view.RedirectView;
 
+import static org.junit.Assert.*;
+
 /**
  * Test fixture with {@link ServletInvocableHandlerMethod}.
  *
@@ -73,7 +77,7 @@ public class ServletInvocableHandlerMethodTests {
 
 	@Test
 	public void invokeAndHandle_VoidWithResponseStatus() throws Exception {
-		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod("responseStatus");
+		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod(new Handler(), "responseStatus");
 		handlerMethod.invokeAndHandle(webRequest, mavContainer);
 
 		assertTrue("Null return value + @ResponseStatus should result in 'request handled'",
@@ -85,7 +89,7 @@ public class ServletInvocableHandlerMethodTests {
 	public void invokeAndHandle_VoidWithHttpServletResponseArgument() throws Exception {
 		argumentResolvers.addResolver(new ServletResponseMethodArgumentResolver());
 
-		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod("httpServletResponse", HttpServletResponse.class);
+		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod(new Handler(), "httpServletResponse", HttpServletResponse.class);
 		handlerMethod.invokeAndHandle(webRequest, mavContainer);
 
 		assertTrue("Null return value + HttpServletResponse arg should result in 'request handled'",
@@ -98,7 +102,7 @@ public class ServletInvocableHandlerMethodTests {
 		int lastModifiedTimestamp = 1000 * 1000;
 		webRequest.checkNotModified(lastModifiedTimestamp);
 
-		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod("notModified");
+		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod(new Handler(), "notModified");
 		handlerMethod.invokeAndHandle(webRequest, mavContainer);
 
 		assertTrue("Null return value + 'not modified' request should result in 'request handled'",
@@ -109,7 +113,7 @@ public class ServletInvocableHandlerMethodTests {
 
 	@Test
 	public void invokeAndHandle_NotVoidWithResponseStatusAndReason() throws Exception {
-		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod("responseStatusWithReason");
+		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod(new Handler(), "responseStatusWithReason");
 		handlerMethod.invokeAndHandle(webRequest, mavContainer);
 
 		assertTrue("When a phrase is used, the response should not be used any more", mavContainer.isRequestHandled());
@@ -121,7 +125,7 @@ public class ServletInvocableHandlerMethodTests {
 	public void invokeAndHandle_Exception() throws Exception {
 		returnValueHandlers.addHandler(new ExceptionRaisingReturnValueHandler());
 
-		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod("handle");
+		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod(new Handler(), "handle");
 		handlerMethod.invokeAndHandle(webRequest, mavContainer);
 		fail("Expected exception");
 	}
@@ -133,7 +137,7 @@ public class ServletInvocableHandlerMethodTests {
 		returnValueHandlers.addHandler(new ViewNameMethodReturnValueHandler());
 
 		// Invoke without a request parameter (String return value)
-		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod("dynamicReturnValue", String.class);
+		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod(new Handler(), "dynamicReturnValue", String.class);
 		handlerMethod.invokeAndHandle(webRequest, mavContainer);
 
 		assertNotNull(mavContainer.getView());
@@ -146,11 +150,45 @@ public class ServletInvocableHandlerMethodTests {
 		assertEquals("view", mavContainer.getViewName());
 	}
 
+	@Test
+	public void wrapConcurrentResult_MethodLevelResponseBody() throws Exception {
+		wrapConcurrentResult_ResponseBody(new MethodLevelResponseBodyHandler());
+	}
+
+	@Test
+	public void wrapConcurrentResult_TypeLevelResponseBody() throws Exception {
+		wrapConcurrentResult_ResponseBody(new TypeLevelResponseBodyHandler());
+	}
+
+	private void wrapConcurrentResult_ResponseBody(Object handler) throws Exception {
+		List<HttpMessageConverter<?>> converters = new ArrayList<HttpMessageConverter<?>>();
+		converters.add(new StringHttpMessageConverter());
+		returnValueHandlers.addHandler(new RequestResponseBodyMethodProcessor(converters));
+		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod(handler, "handle");
+		handlerMethod = handlerMethod.wrapConcurrentResult("bar");
+		handlerMethod.invokeAndHandle(webRequest, mavContainer);
+
+		assertEquals("bar", response.getContentAsString());
+	}
+
+	@Test
+	public void wrapConcurrentResult_ResponseEntity() throws Exception {
+		List<HttpMessageConverter<?>> converters = new ArrayList<HttpMessageConverter<?>>();
+		converters.add(new StringHttpMessageConverter());
+		returnValueHandlers.addHandler(new HttpEntityMethodProcessor(converters));
+		ServletInvocableHandlerMethod handlerMethod = getHandlerMethod(new ResponseEntityHandler(), "handle");
+		handlerMethod = handlerMethod.wrapConcurrentResult(new ResponseEntity<>("bar", HttpStatus.OK));
+		handlerMethod.invokeAndHandle(webRequest, mavContainer);
+
+		assertEquals("bar", response.getContentAsString());
+	}
 
-	private ServletInvocableHandlerMethod getHandlerMethod(String methodName, Class<?>... argTypes)
-			throws NoSuchMethodException {
-		Method method = Handler.class.getDeclaredMethod(methodName, argTypes);
-		ServletInvocableHandlerMethod handlerMethod = new ServletInvocableHandlerMethod(new Handler(), method);
+
+	private ServletInvocableHandlerMethod getHandlerMethod(Object controller,
+			String methodName, Class<?>... argTypes) throws NoSuchMethodException {
+
+		Method method = controller.getClass().getDeclaredMethod(methodName, argTypes);
+		ServletInvocableHandlerMethod handlerMethod = new ServletInvocableHandlerMethod(controller, method);
 		handlerMethod.setHandlerMethodArgumentResolvers(argumentResolvers);
 		handlerMethod.setHandlerMethodReturnValueHandlers(returnValueHandlers);
 		return handlerMethod;
@@ -183,6 +221,31 @@ public class ServletInvocableHandlerMethodTests {
 		}
 	}
 
+	private static class MethodLevelResponseBodyHandler {
+
+		@ResponseBody
+		public DeferredResult<String> handle() {
+			return new DeferredResult<>();
+		}
+	}
+
+	@ResponseBody
+	private static class TypeLevelResponseBodyHandler {
+
+		@SuppressWarnings("unused")
+		public DeferredResult<String> handle() {
+			return new DeferredResult<String>();
+		}
+	}
+
+	private static class ResponseEntityHandler {
+
+		public DeferredResult<ResponseEntity<String>> handle() {
+			return new DeferredResult<>();
+		}
+	}
+
+
 	private static class ExceptionRaisingReturnValueHandler implements HandlerMethodReturnValueHandler {
 
 		@Override