WebFluxResponseStatusExceptionHandler for @ResponseStatus introspection

The web.server package is quite low-level and should not depend on web.bind in order to avoid a dependency cycle. Extracting the introspection of the ResponseStatus annotation into a WebFlux-level subclass resolves the cycle.

Issue: SPR-16567

spring-web/src/main/java/org/springframework/web/server/handler/ResponseStatusExceptionHandler.java

@@ -20,22 +20,15 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import reactor.core.publisher.Mono;
 
-import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.lang.Nullable;
-import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.server.ResponseStatusException;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebExceptionHandler;
 
 /**
- * Handle instances of {@link ResponseStatusException}, or of exceptions annotated
- * with {@link ResponseStatus @ResponseStatus}, by extracting the
- * {@code HttpStatus} from them and updating the status of the response.
- *
- * <p>If the response is already committed, the error remains unresolved and is
- * propagated.
+ * Handle {@link ResponseStatusException} by setting the response status.
  *
  * @author Rossen Stoyanchev
  * @author Sebastien Deleuze
@@ -48,7 +41,7 @@ public class ResponseStatusExceptionHandler implements WebExceptionHandler {
 
 	@Override
 	public Mono<Void> handle(ServerWebExchange exchange, Throwable ex) {
-		HttpStatus status = resolveHttpStatus(ex);
+		HttpStatus status = resolveStatus(ex);
 		if (status != null && exchange.getResponse().setStatusCode(status)) {
 			if (status.is5xxServerError()) {
 				logger.error(buildMessage(exchange.getRequest(), ex));
@@ -64,24 +57,34 @@ public class ResponseStatusExceptionHandler implements WebExceptionHandler {
 		return Mono.error(ex);
 	}
 
+	private String buildMessage(ServerHttpRequest request, Throwable ex) {
+		return "Failed to handle request [" + request.getMethod() + " " + request.getURI() + "]: " + ex.getMessage();
+	}
+
+	@Nullable
+	private HttpStatus resolveStatus(Throwable ex) {
+		HttpStatus status = determineStatus(ex);
+		if (status == null) {
+			Throwable cause = ex.getCause();
+			if (cause != null) {
+				status = resolveStatus(cause);
+			}
+		}
+		return status;
+	}
+
+	/**
+	 * Determine the HTTP status implied by the given exception.
+	 * @param ex the exception to introspect
+	 * @return the associated HTTP status, if any
+	 * @since 5.0.5
+	 */
 	@Nullable
-	private HttpStatus resolveHttpStatus(Throwable ex) {
+	protected HttpStatus determineStatus(Throwable ex) {
 		if (ex instanceof ResponseStatusException) {
 			return ((ResponseStatusException) ex).getStatus();
 		}
-		ResponseStatus status = AnnotatedElementUtils.findMergedAnnotation(ex.getClass(), ResponseStatus.class);
-		if (status != null) {
-			return status.code();
-		}
-		if (ex.getCause() != null) {
-			return resolveHttpStatus(ex.getCause());
-		}
 		return null;
 	}
 
-	private String buildMessage(ServerHttpRequest request, Throwable ex) {
-		return "Failed to handle request [" + request.getMethod() + " "
-				+ request.getURI() + "]: " + ex.getMessage();
-	}
-
-}
+}

spring-web/src/test/java/org/springframework/web/server/handler/ResponseStatusExceptionHandlerTests.java

@@ -18,6 +18,7 @@ package org.springframework.web.server.handler;
 
 import java.time.Duration;
 
+import org.junit.Before;
 import org.junit.Test;
 import reactor.core.publisher.Mono;
 import reactor.test.StepVerifier;
@@ -25,21 +26,31 @@ import reactor.test.StepVerifier;
 import org.springframework.http.HttpStatus;
 import org.springframework.mock.http.server.reactive.test.MockServerHttpRequest;
 import org.springframework.mock.web.test.server.MockServerWebExchange;
-import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.server.ResponseStatusException;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertSame;
+import static org.junit.Assert.*;
 
 /**
  * Unit tests for {@link ResponseStatusExceptionHandler}.
+ *
  * @author Rossen Stoyanchev
+ * @author Juergen Hoeller
  */
 public class ResponseStatusExceptionHandlerTests {
 
-	private final ResponseStatusExceptionHandler handler = new ResponseStatusExceptionHandler();
+	protected final MockServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get("/"));
+
+	protected ResponseStatusExceptionHandler handler;
 
-	private final MockServerWebExchange exchange = MockServerWebExchange.from(MockServerHttpRequest.get("/"));
+
+	@Before
+	public void setup() {
+		this.handler = createResponseStatusExceptionHandler();
+	}
+
+	protected ResponseStatusExceptionHandler createResponseStatusExceptionHandler() {
+		return new ResponseStatusExceptionHandler();
+	}
 
 
 	@Test
@@ -49,13 +60,6 @@ public class ResponseStatusExceptionHandlerTests {
 		assertEquals(HttpStatus.BAD_REQUEST, this.exchange.getResponse().getStatusCode());
 	}
 
-	@Test
-	public void handleAnnotatedException() {
-		Throwable ex = new CustomException();
-		this.handler.handle(this.exchange, ex).block(Duration.ofSeconds(5));
-		assertEquals(HttpStatus.I_AM_A_TEAPOT, this.exchange.getResponse().getStatusCode());
-	}
-
 	@Test
 	public void handleNestedResponseStatusException() {
 		Throwable ex = new Exception(new ResponseStatusException(HttpStatus.BAD_REQUEST, ""));
@@ -63,13 +67,6 @@ public class ResponseStatusExceptionHandlerTests {
 		assertEquals(HttpStatus.BAD_REQUEST, this.exchange.getResponse().getStatusCode());
 	}
 
-	@Test
-	public void handleNestedAnnotatedException() {
-		Throwable ex = new Exception(new CustomException());
-		this.handler.handle(this.exchange, ex).block(Duration.ofSeconds(5));
-		assertEquals(HttpStatus.I_AM_A_TEAPOT, this.exchange.getResponse().getStatusCode());
-	}
-
 	@Test
 	public void unresolvedException() {
 		Throwable expected = new IllegalStateException();
@@ -77,7 +74,7 @@ public class ResponseStatusExceptionHandlerTests {
 		StepVerifier.create(mono).consumeErrorWith(actual -> assertSame(expected, actual)).verify();
 	}
 
-	@Test // SPR-16231
+	@Test  // SPR-16231
 	public void responseCommitted() {
 		Throwable ex = new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "Oops");
 		this.exchange.getResponse().setStatusCode(HttpStatus.CREATED);
@@ -86,9 +83,4 @@ public class ResponseStatusExceptionHandlerTests {
 		StepVerifier.create(mono).consumeErrorWith(actual -> assertSame(ex, actual)).verify();
 	}
 
-
-	@ResponseStatus(HttpStatus.I_AM_A_TEAPOT)
-	private static class CustomException extends Exception {
-	}
-
 }

spring-webflux/src/main/java/org/springframework/web/reactive/config/WebFluxConfigurationSupport.java

@@ -52,6 +52,7 @@ import org.springframework.web.reactive.function.server.support.HandlerFunctionA
 import org.springframework.web.reactive.function.server.support.RouterFunctionMapping;
 import org.springframework.web.reactive.function.server.support.ServerResponseResultHandler;
 import org.springframework.web.reactive.handler.AbstractHandlerMapping;
+import org.springframework.web.reactive.handler.WebFluxResponseStatusExceptionHandler;
 import org.springframework.web.reactive.result.SimpleHandlerAdapter;
 import org.springframework.web.reactive.result.method.annotation.ArgumentResolverConfigurer;
 import org.springframework.web.reactive.result.method.annotation.RequestMappingHandlerAdapter;
@@ -62,7 +63,6 @@ import org.springframework.web.reactive.result.view.ViewResolutionResultHandler;
 import org.springframework.web.reactive.result.view.ViewResolver;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebExceptionHandler;
-import org.springframework.web.server.handler.ResponseStatusExceptionHandler;
 import org.springframework.web.server.i18n.AcceptHeaderLocaleContextResolver;
 import org.springframework.web.server.i18n.LocaleContextResolver;
 
@@ -108,7 +108,7 @@ public class WebFluxConfigurationSupport implements ApplicationContextAware {
 	@Bean
 	@Order(0)
 	public WebExceptionHandler responseStatusExceptionHandler() {
-		return new ResponseStatusExceptionHandler();
+		return new WebFluxResponseStatusExceptionHandler();
 	}
 
 	@Bean

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultHandlerStrategiesBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -25,10 +25,10 @@ import org.springframework.http.codec.HttpMessageReader;
 import org.springframework.http.codec.HttpMessageWriter;
 import org.springframework.http.codec.ServerCodecConfigurer;
 import org.springframework.util.Assert;
+import org.springframework.web.reactive.handler.WebFluxResponseStatusExceptionHandler;
 import org.springframework.web.reactive.result.view.ViewResolver;
 import org.springframework.web.server.WebExceptionHandler;
 import org.springframework.web.server.WebFilter;
-import org.springframework.web.server.handler.ResponseStatusExceptionHandler;
 import org.springframework.web.server.i18n.AcceptHeaderLocaleContextResolver;
 import org.springframework.web.server.i18n.LocaleContextResolver;
 
@@ -58,7 +58,7 @@ class DefaultHandlerStrategiesBuilder implements HandlerStrategies.Builder {
 
 	public void defaultConfiguration() {
 		this.codecConfigurer.registerDefaults(true);
-		this.exceptionHandlers.add(new ResponseStatusExceptionHandler());
+		this.exceptionHandlers.add(new WebFluxResponseStatusExceptionHandler());
 		this.localeContextResolver = new AcceptHeaderLocaleContextResolver();
 	}
 

spring-webflux/src/main/java/org/springframework/web/reactive/handler/WebFluxResponseStatusExceptionHandler.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2002-2018 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.reactive.handler;
+
+import org.springframework.core.annotation.AnnotatedElementUtils;
+import org.springframework.http.HttpStatus;
+import org.springframework.lang.Nullable;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.server.handler.ResponseStatusExceptionHandler;
+
+/**
+ * Common WebFlux exception handler that detects instances of
+ * {@link org.springframework.web.server.ResponseStatusException}
+ * (inherited from the base class) as well as exceptions annotated with
+ * {@link ResponseStatus @ResponseStatus} by determining the HTTP status
+ * for them and updating the status of the response accordingly.
+ *
+ * <p>If the response is already committed, the error remains unresolved
+ * and is propagated.
+ *
+ * @author Juergen Hoeller
+ * @author Rossen Stoyanchev
+ * @since 5.0.5
+ */
+public class WebFluxResponseStatusExceptionHandler extends ResponseStatusExceptionHandler {
+
+	@Override
+	@Nullable
+	protected HttpStatus determineStatus(Throwable ex) {
+		HttpStatus status = super.determineStatus(ex);
+		if (status == null) {
+			ResponseStatus ann = AnnotatedElementUtils.findMergedAnnotation(ex.getClass(), ResponseStatus.class);
+			if (ann != null) {
+				status = ann.code();
+			}
+		}
+		return status;
+	}
+
+}

spring-webflux/src/test/java/org/springframework/web/reactive/handler/WebFluxResponseStatusExceptionHandlerTests.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2002-2018 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.reactive.handler;
+
+import java.time.Duration;
+
+import org.junit.Test;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.reactive.handler.WebFluxResponseStatusExceptionHandler;
+import org.springframework.web.server.handler.ResponseStatusExceptionHandler;
+import org.springframework.web.server.handler.ResponseStatusExceptionHandlerTests;
+
+import static org.junit.Assert.*;
+
+/**
+ * Unit tests for {@link WebFluxResponseStatusExceptionHandler}.
+ *
+ * @author Juergen Hoeller
+ * @author Rossen Stoyanchev
+ */
+public class WebFluxResponseStatusExceptionHandlerTests extends ResponseStatusExceptionHandlerTests {
+
+	@Override
+	protected ResponseStatusExceptionHandler createResponseStatusExceptionHandler() {
+		return new WebFluxResponseStatusExceptionHandler();
+	}
+
+
+	@Test
+	public void handleAnnotatedException() {
+		Throwable ex = new CustomException();
+		this.handler.handle(this.exchange, ex).block(Duration.ofSeconds(5));
+		assertEquals(HttpStatus.I_AM_A_TEAPOT, this.exchange.getResponse().getStatusCode());
+	}
+
+	@Test
+	public void handleNestedAnnotatedException() {
+		Throwable ex = new Exception(new CustomException());
+		this.handler.handle(this.exchange, ex).block(Duration.ofSeconds(5));
+		assertEquals(HttpStatus.I_AM_A_TEAPOT, this.exchange.getResponse().getStatusCode());
+	}
+
+
+	@SuppressWarnings("serial")
+	@ResponseStatus(HttpStatus.I_AM_A_TEAPOT)
+	private static class CustomException extends Exception {
+	}
+
+}