Support ResponseStatus on reactive controllers

This commit adds support for `@ResponseStatus` annotations on reactive
controller methods. `HandlerResultHandler`s implementations now
set the status on the `ServerWebExchange`, if and only if the
invocation of the controller method succeeded.

Issue: SPR-14830

spring-web-reactive/src/main/java/org/springframework/web/reactive/result/AbstractHandlerResultHandler.java

@@ -23,10 +23,13 @@ import java.util.List;
 import java.util.Optional;
 import java.util.Set;
 
+import org.springframework.core.MethodParameter;
 import org.springframework.core.Ordered;
 import org.springframework.core.ReactiveAdapterRegistry;
+import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.http.MediaType;
 import org.springframework.util.Assert;
+import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.reactive.HandlerMapping;
 import org.springframework.web.reactive.accept.RequestedContentTypeResolver;
 import org.springframework.web.server.ServerWebExchange;
@@ -38,7 +41,7 @@ import org.springframework.web.server.ServerWebExchange;
  * @author Rossen Stoyanchev
  * @since 5.0
  */
-public abstract class ContentNegotiatingResultHandlerSupport implements Ordered {
+public abstract class AbstractHandlerResultHandler implements Ordered {
 
 	private static final MediaType MEDIA_TYPE_APPLICATION_ALL = new MediaType("application");
 
@@ -50,11 +53,11 @@ public abstract class ContentNegotiatingResultHandlerSupport implements Ordered
 	private int order = LOWEST_PRECEDENCE;
 
 
-	protected ContentNegotiatingResultHandlerSupport(RequestedContentTypeResolver contentTypeResolver) {
+	protected AbstractHandlerResultHandler(RequestedContentTypeResolver contentTypeResolver) {
 		this(contentTypeResolver, new ReactiveAdapterRegistry());
 	}
 
-	protected ContentNegotiatingResultHandlerSupport(RequestedContentTypeResolver contentTypeResolver,
+	protected AbstractHandlerResultHandler(RequestedContentTypeResolver contentTypeResolver,
 			ReactiveAdapterRegistry adapterRegistry) {
 
 		Assert.notNull(contentTypeResolver, "'contentTypeResolver' is required.");
@@ -151,4 +154,17 @@ public abstract class ContentNegotiatingResultHandlerSupport implements Ordered
 		return (comparator.compare(acceptable, producible) <= 0 ? acceptable : producible);
 	}
 
+	/**
+	 * Optionally set the response status using the information provided by {@code @ResponseStatus}.
+	 * @param methodParameter the controller method return parameter
+	 * @param exchange the server exchange being handled
+	 */
+	protected void updateResponseStatus(MethodParameter methodParameter, ServerWebExchange exchange) {
+		ResponseStatus annotation = methodParameter.getMethodAnnotation(ResponseStatus.class);
+		if (annotation != null) {
+			annotation = AnnotationUtils.synthesizeAnnotation(annotation, methodParameter.getMethod());
+			exchange.getResponse().setStatusCode(annotation.code());
+		}
+	}
+
 }

spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/annotation/AbstractMessageWriterResultHandler.java

@@ -33,7 +33,7 @@ import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.util.Assert;
 import org.springframework.web.reactive.accept.RequestedContentTypeResolver;
-import org.springframework.web.reactive.result.ContentNegotiatingResultHandlerSupport;
+import org.springframework.web.reactive.result.AbstractHandlerResultHandler;
 import org.springframework.web.server.NotAcceptableStatusException;
 import org.springframework.web.server.ServerWebExchange;
 
@@ -44,7 +44,7 @@ import org.springframework.web.server.ServerWebExchange;
  * @author Rossen Stoyanchev
  * @since 5.0
  */
-public abstract class AbstractMessageWriterResultHandler extends ContentNegotiatingResultHandlerSupport {
+public abstract class AbstractMessageWriterResultHandler extends AbstractHandlerResultHandler {
 
 	private final List<HttpMessageWriter<?>> messageWriters;
 
@@ -110,7 +110,8 @@ public abstract class AbstractMessageWriterResultHandler extends ContentNegotiat
 		}
 
 		if (void.class == elementType.getRawClass() || Void.class == elementType.getRawClass()) {
-			return Mono.from((Publisher<Void>) publisher);
+			return Mono.from((Publisher<Void>) publisher)
+					.doOnSubscribe(sub -> updateResponseStatus(bodyParameter, exchange));
 		}
 
 		List<MediaType> producibleTypes = getProducibleMediaTypes(elementType);
@@ -125,11 +126,12 @@ public abstract class AbstractMessageWriterResultHandler extends ContentNegotiat
 		if (bestMediaType != null) {
 			for (HttpMessageWriter<?> messageWriter : getMessageWriters()) {
 				if (messageWriter.canWrite(elementType, bestMediaType)) {
-					return (messageWriter instanceof ServerHttpMessageWriter ?
-							((ServerHttpMessageWriter<?>)messageWriter).write((Publisher) publisher,
+					Mono<Void> bodyWriter = (messageWriter instanceof ServerHttpMessageWriter ?
+							((ServerHttpMessageWriter<?>) messageWriter).write((Publisher) publisher,
 									bodyType, elementType, bestMediaType, request, response, Collections.emptyMap()) :
 							messageWriter.write((Publisher) publisher, elementType,
 									bestMediaType, response, Collections.emptyMap()));
+					return bodyWriter.doOnSubscribe(sub -> updateResponseStatus(bodyParameter, exchange));
 				}
 			}
 		}

spring-web-reactive/src/main/java/org/springframework/web/reactive/result/view/ViewResolutionResultHandler.java

@@ -43,7 +43,7 @@ import org.springframework.web.bind.annotation.ModelAttribute;
 import org.springframework.web.reactive.HandlerResult;
 import org.springframework.web.reactive.HandlerResultHandler;
 import org.springframework.web.reactive.accept.RequestedContentTypeResolver;
-import org.springframework.web.reactive.result.ContentNegotiatingResultHandlerSupport;
+import org.springframework.web.reactive.result.AbstractHandlerResultHandler;
 import org.springframework.web.server.NotAcceptableStatusException;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.util.HttpRequestPathHelper;
@@ -74,7 +74,7 @@ import org.springframework.web.util.HttpRequestPathHelper;
  * @author Rossen Stoyanchev
  * @since 5.0
  */
-public class ViewResolutionResultHandler extends ContentNegotiatingResultHandlerSupport
+public class ViewResolutionResultHandler extends AbstractHandlerResultHandler
 		implements HandlerResultHandler, Ordered {
 
 	private final List<ViewResolver> viewResolvers = new ArrayList<>(4);
@@ -208,6 +208,7 @@ public class ViewResolutionResultHandler extends ContentNegotiatingResultHandler
 		}
 		Map<String, ?> model = result.getModel();
 		return viewMono.then(view -> {
+			updateResponseStatus(result.getReturnTypeSource(), exchange);
 			if (view instanceof View) {
 				return ((View) view).render(model, null, exchange);
 			}

spring-web-reactive/src/test/java/org/springframework/web/reactive/result/HandlerResultHandlerTests.java

@@ -46,10 +46,10 @@ import static org.springframework.http.MediaType.TEXT_PLAIN;
 import static org.springframework.web.reactive.HandlerMapping.PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE;
 
 /**
- * Unit tests for {@link ContentNegotiatingResultHandlerSupport}.
+ * Unit tests for {@link AbstractHandlerResultHandler}.
  * @author Rossen Stoyanchev
  */
-public class ContentNegotiatingResultHandlerSupportTests {
+public class HandlerResultHandlerTests {
 
 	private TestResultHandler resultHandler;
 
@@ -117,7 +117,7 @@ public class ContentNegotiatingResultHandlerSupportTests {
 
 
 	@SuppressWarnings("WeakerAccess")
-	private static class TestResultHandler extends ContentNegotiatingResultHandlerSupport {
+	private static class TestResultHandler extends AbstractHandlerResultHandler {
 
 		protected TestResultHandler() {
 			this(new HeaderContentTypeResolver());

spring-web-reactive/src/test/java/org/springframework/web/reactive/result/method/annotation/ResponseBodyResultHandlerTests.java

@@ -23,12 +23,14 @@ import java.util.List;
 import org.junit.Before;
 import org.junit.Test;
 import reactor.core.publisher.Mono;
+import reactor.test.StepVerifier;
 import rx.Completable;
 import rx.Single;
 
 import org.springframework.core.codec.ByteBufferEncoder;
 import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.http.codec.EncoderHttpMessageWriter;
 import org.springframework.http.codec.HttpMessageWriter;
@@ -42,6 +44,7 @@ import org.springframework.stereotype.Controller;
 import org.springframework.ui.ExtendedModelMap;
 import org.springframework.util.ObjectUtils;
 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.method.HandlerMethod;
 import org.springframework.web.reactive.HandlerResult;
@@ -114,6 +117,22 @@ public class ResponseBodyResultHandlerTests {
 		testSupports(controller, "handleToMonoResponseEntity", false);
 	}
 
+	@Test
+	public void writeResponseStatus() throws NoSuchMethodException {
+		Object controller = new TestRestController();
+		HandlerMethod hm = handlerMethod(controller, "handleToString");
+		HandlerResult handlerResult = new HandlerResult(hm, null, hm.getReturnType(), new ExtendedModelMap());
+
+		StepVerifier.create(this.resultHandler.handleResult(this.exchange, handlerResult)).expectComplete().verify();
+		assertEquals(HttpStatus.NO_CONTENT, this.response.getStatusCode());
+
+		hm = handlerMethod(controller, "handleToMonoVoid");
+		handlerResult = new HandlerResult(hm, null, hm.getReturnType(), new ExtendedModelMap());
+
+		StepVerifier.create(this.resultHandler.handleResult(this.exchange, handlerResult)).expectComplete().verify();
+		assertEquals(HttpStatus.CREATED, this.response.getStatusCode());
+	}
+
 	private void testSupports(Object controller, String method, boolean result) throws NoSuchMethodException {
 		HandlerMethod hm = handlerMethod(controller, method);
 		HandlerResult handlerResult = new HandlerResult(hm, null, hm.getReturnType(), new ExtendedModelMap());
@@ -134,6 +153,10 @@ public class ResponseBodyResultHandlerTests {
 	@RestController @SuppressWarnings("unused")
 	private static class TestRestController {
 
+		@ResponseStatus(code = HttpStatus.CREATED)
+		public Mono<Void> handleToMonoVoid() { return null;}
+
+		@ResponseStatus(code = HttpStatus.NO_CONTENT)
 		public String handleToString() {
 			return null;
 		}

spring-web-reactive/src/test/java/org/springframework/web/reactive/result/view/ViewResolutionResultHandlerTests.java

@@ -42,6 +42,7 @@ import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DefaultDataBufferFactory;
 import org.springframework.core.io.buffer.support.DataBufferTestUtils;
 import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.mock.http.server.reactive.test.MockServerHttpRequest;
@@ -50,6 +51,7 @@ import org.springframework.ui.ExtendedModelMap;
 import org.springframework.ui.Model;
 import org.springframework.ui.ModelMap;
 import org.springframework.web.bind.annotation.ModelAttribute;
+import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.reactive.HandlerResult;
 import org.springframework.web.reactive.accept.HeaderContentTypeResolver;
 import org.springframework.web.reactive.accept.RequestedContentTypeResolver;
@@ -128,18 +130,22 @@ public class ViewResolutionResultHandlerTests {
 		returnType = ResolvableType.forClass(View.class);
 		returnValue = new TestView("account");
 		testHandle("/path", returnType, returnValue, "account: {id=123}");
+		assertEquals(HttpStatus.NO_CONTENT, this.exchange.getResponse().getStatusCode());
 
 		returnType = ResolvableType.forClassWithGenerics(Mono.class, View.class);
 		returnValue = Mono.just(new TestView("account"));
 		testHandle("/path", returnType, returnValue, "account: {id=123}");
+		assertEquals(HttpStatus.SEE_OTHER, this.exchange.getResponse().getStatusCode());
 
 		returnType = ResolvableType.forClass(String.class);
 		returnValue = "account";
 		testHandle("/path", returnType, returnValue, "account: {id=123}", resolver);
+		assertEquals(HttpStatus.CREATED, this.exchange.getResponse().getStatusCode());
 
 		returnType = ResolvableType.forClassWithGenerics(Mono.class, String.class);
 		returnValue = Mono.just("account");
 		testHandle("/path", returnType, returnValue, "account: {id=123}", resolver);
+		assertEquals(HttpStatus.PARTIAL_CONTENT, this.exchange.getResponse().getStatusCode());
 
 		returnType = ResolvableType.forClass(Model.class);
 		returnValue = new ExtendedModelMap().addAttribute("name", "Joe");
@@ -392,12 +398,16 @@ public class ViewResolutionResultHandlerTests {
 	@SuppressWarnings("unused")
 	private static class TestController {
 
+		@ResponseStatus(code = HttpStatus.CREATED)
 		String string() { return null; }
 
+		@ResponseStatus(HttpStatus.NO_CONTENT)
 		View view() { return null; }
 
+		@ResponseStatus(HttpStatus.PARTIAL_CONTENT)
 		Mono<String> monoString() { return null; }
 
+		@ResponseStatus(code = HttpStatus.SEE_OTHER)
 		Mono<View> monoView() { return null; }
 
 		Mono<Void> monoVoid() { return null; }