Add HttpExceptionHandler

spring-web-reactive/src/main/java/org/springframework/http/server/reactive/ErrorHandlingHttpHandler.java

+/*
+ * Copyright 2002-2015 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.http.server.reactive;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.reactivestreams.Publisher;
+import reactor.Publishers;
+import reactor.core.publisher.convert.RxJava1Converter;
+import rx.Observable;
+
+import org.springframework.util.Assert;
+
+/**
+ * {@link HttpHandler} that delegates to a target {@link HttpHandler} and handles
+ * any errors from it by invoking one or more {@link HttpExceptionHandler}s
+ * sequentially until one of them completes successfully.
+ *
+ * @author Rossen Stoyanchev
+ */
+public class ErrorHandlingHttpHandler extends HttpHandlerDecorator {
+
+	private final List<HttpExceptionHandler> exceptionHandlers;
+
+
+	public ErrorHandlingHttpHandler(HttpHandler targetHandler, HttpExceptionHandler... exceptionHandlers) {
+		super(targetHandler);
+		Assert.notEmpty(exceptionHandlers, "At least one exception handler is required");
+		this.exceptionHandlers = Arrays.asList(exceptionHandlers);
+	}
+
+
+	@Override
+	public Publisher<Void> handle(ServerHttpRequest request, ServerHttpResponse response) {
+		Publisher<Void> publisher;
+		try {
+			publisher = getDelegate().handle(request, response);
+		}
+		catch (Throwable ex) {
+			publisher = Publishers.error(ex);
+		}
+		for (HttpExceptionHandler handler : this.exceptionHandlers) {
+			publisher = applyExceptionHandler(publisher, handler, request, response);
+		}
+		return publisher;
+	}
+
+	private static Publisher<Void> applyExceptionHandler(Publisher<Void> publisher,
+			HttpExceptionHandler handler, ServerHttpRequest request, ServerHttpResponse response) {
+
+		// see https://github.com/reactor/reactor/issues/580
+
+		Observable<Void> observable = RxJava1Converter.from(publisher).onErrorResumeNext(ex -> {
+			return RxJava1Converter.from(handler.handle(request, response, ex));
+		});
+		return RxJava1Converter.from(observable);
+	}
+
+}

spring-web-reactive/src/main/java/org/springframework/http/server/reactive/HttpExceptionHandler.java

+/*
+ * Copyright 2002-2015 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.http.server.reactive;
+
+import org.reactivestreams.Publisher;
+
+/**
+ * A contract for resolving exceptions from HTTP request handling.
+ *
+ * <p>{@link ErrorHandlingHttpHandler} provides a way of applying a list
+ * {@link HttpExceptionHandler}s to a target {@link HttpHandler}.
+ *
+ * @author Rossen Stoyanchev
+ * @see ErrorHandlingHttpHandler
+ */
+public interface HttpExceptionHandler {
+
+	/**
+	 * Handle the given exception and return a completion Publisher to indicate
+	 * when error handling is complete, or send an error signal if the exception
+	 * was not handled.
+	 *
+	 * @param request the current request
+	 * @param response the current response
+	 * @param ex the exception to handle
+	 * @return Publisher to indicate when exception handling is complete.
+	 */
+	Publisher<Void> handle(ServerHttpRequest request, ServerHttpResponse response, Throwable ex);
+
+}

spring-web-reactive/src/test/java/org/springframework/http/server/reactive/ErrorHandlingHttpHandlerTests.java

+/*
+ * Copyright 2002-2015 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.http.server.reactive;
+
+
+import java.net.URI;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.reactivestreams.Publisher;
+import reactor.Publishers;
+import reactor.rx.Streams;
+import reactor.rx.action.Signal;
+
+import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpStatus;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * @author Rossen Stoyanchev
+ */
+@SuppressWarnings("ThrowableResultOfMethodCallIgnored")
+public class ErrorHandlingHttpHandlerTests {
+
+	private MockServerHttpRequest request;
+
+	private MockServerHttpResponse response;
+
+
+	@Before
+	public void setUp() throws Exception {
+		this.request = new MockServerHttpRequest(HttpMethod.GET, new URI("http://localhost:8080"));
+		this.response = new MockServerHttpResponse();
+	}
+
+
+	@Test
+	public void handleErrorSignal() throws Exception {
+		HttpExceptionHandler exceptionHandler = new UnresolvedExceptionHandler();
+		HttpHandler targetHandler = new TestHttpHandler(new IllegalStateException("boo"));
+		HttpHandler handler = new ErrorHandlingHttpHandler(targetHandler, exceptionHandler);
+
+		Publisher<Void> publisher = handler.handle(this.request, this.response);
+		Streams.wrap(publisher).toList().await(5, TimeUnit.SECONDS);
+
+		assertEquals(HttpStatus.INTERNAL_SERVER_ERROR, this.response.getStatus());
+	}
+
+	@Test
+	public void handleErrorSignalWithMultipleHttpErrorHandlers() throws Exception {
+		HttpExceptionHandler[] exceptionHandlers = new HttpExceptionHandler[] {
+				new UnresolvedExceptionHandler(),
+				new UnresolvedExceptionHandler(),
+				new HttpStatusExceptionHandler(HttpStatus.INTERNAL_SERVER_ERROR),
+				new UnresolvedExceptionHandler()
+		};
+		HttpHandler targetHandler = new TestHttpHandler(new IllegalStateException("boo"));
+		HttpHandler httpHandler = new ErrorHandlingHttpHandler(targetHandler, exceptionHandlers);
+
+		Publisher<Void> publisher = httpHandler.handle(this.request, this.response);
+		Streams.wrap(publisher).toList().await(5, TimeUnit.SECONDS);
+
+		assertEquals(HttpStatus.INTERNAL_SERVER_ERROR, this.response.getStatus());
+	}
+
+	@Test
+	public void unresolvedException() throws Exception {
+		HttpExceptionHandler exceptionHandler = new UnresolvedExceptionHandler();
+		HttpHandler targetHandler = new TestHttpHandler(new IllegalStateException("boo"));
+		HttpHandler httpHandler = new ErrorHandlingHttpHandler(targetHandler, exceptionHandler);
+
+		Publisher<Void> publisher = httpHandler.handle(this.request, this.response);
+		Throwable ex = awaitErrorSignal(publisher);
+
+		assertEquals("boo", ex.getMessage());
+		assertNull(this.response.getStatus());
+	}
+
+	@Test
+	public void thrownExceptionBecomesErrorSignal() throws Exception {
+		HttpExceptionHandler exceptionHandler = new HttpStatusExceptionHandler(HttpStatus.INTERNAL_SERVER_ERROR);
+		HttpHandler targetHandler = new TestHttpHandler(new IllegalStateException("boo"), true);
+		HttpHandler handler = new ErrorHandlingHttpHandler(targetHandler, exceptionHandler);
+
+		Publisher<Void> publisher = handler.handle(this.request, this.response);
+		Streams.wrap(publisher).toList().await(5, TimeUnit.SECONDS);
+
+		assertEquals(HttpStatus.INTERNAL_SERVER_ERROR, this.response.getStatus());
+	}
+
+
+	private Throwable awaitErrorSignal(Publisher<?> publisher) throws Exception {
+		Signal<?> signal = Streams.wrap(publisher).materialize().toList().await(5, TimeUnit.SECONDS).get(0);
+		assertEquals("Unexpected signal: " + signal, Signal.Type.ERROR, signal.getType());
+		return signal.getThrowable();
+	}
+
+
+	private static class TestHttpHandler implements HttpHandler {
+
+		private final Throwable exception;
+
+		private final boolean raise;
+
+
+		public TestHttpHandler(Throwable exception) {
+			this(exception, false);
+		}
+
+		public TestHttpHandler(Throwable exception, boolean raise) {
+			this.exception = exception;
+			this.raise = raise;
+			assertTrue(exception instanceof RuntimeException || !this.raise);
+		}
+
+		@Override
+		public Publisher<Void> handle(ServerHttpRequest request, ServerHttpResponse response) {
+			if (this.raise) {
+				throw (RuntimeException) exception;
+			}
+			return Publishers.error(this.exception);
+		}
+	}
+
+
+	/** Leave the exception unresolved. */
+	private static class UnresolvedExceptionHandler implements HttpExceptionHandler {
+
+		@Override
+		public Publisher<Void> handle(ServerHttpRequest request, ServerHttpResponse response, Throwable ex) {
+			return Publishers.error(ex);
+		}
+	}
+
+	/** Set the response status to the given HttpStatus. */
+	private static class HttpStatusExceptionHandler implements HttpExceptionHandler {
+
+		private final HttpStatus status;
+
+		public HttpStatusExceptionHandler(HttpStatus status) {
+			this.status = status;
+		}
+
+		@Override
+		public Publisher<Void> handle(ServerHttpRequest request, ServerHttpResponse response, Throwable ex) {
+			response.setStatusCode(this.status);
+			return Publishers.empty();
+		}
+	}
+
+}

spring-web-reactive/src/test/java/org/springframework/web/reactive/method/InvocableHandlerMethodTests.java

@@ -23,8 +23,6 @@ import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
 import org.junit.Before;
 import org.junit.Test;
 import org.reactivestreams.Publisher;
@@ -49,9 +47,6 @@ import static org.mockito.Mockito.when;
 @SuppressWarnings("ThrowableResultOfMethodCallIgnored")
 public class InvocableHandlerMethodTests {
 
-	private static Log logger = LogFactory.getLog(InvocableHandlerMethodTests.class);
-
-
 	private ServerHttpRequest request;
 
 
@@ -66,9 +61,10 @@ public class InvocableHandlerMethodTests {
 		InvocableHandlerMethod hm = createHandlerMethod("noArgs");
 
 		Publisher<HandlerResult> publisher = hm.invokeForRequest(this.request);
-		Object value = awaitValue(publisher);
+		List<HandlerResult> values = Streams.wrap(publisher).toList().await(5, TimeUnit.SECONDS);
 
-		assertEquals("success", value);
+		assertEquals(1, values.size());
+		assertEquals("success", values.get(0).getValue());
 	}
 
 	@Test
@@ -78,9 +74,10 @@ public class InvocableHandlerMethodTests {
 		hm.setHandlerMethodArgumentResolvers(Collections.singletonList(new RequestParamArgumentResolver()));
 
 		Publisher<HandlerResult> publisher = hm.invokeForRequest(this.request);
-		Object value = awaitValue(publisher);
+		List<HandlerResult> values = Streams.wrap(publisher).toList().await(5, TimeUnit.SECONDS);
 
-		assertEquals("success:null", value);
+		assertEquals(1, values.size());
+		assertEquals("success:null", values.get(0).getValue());
 	}
 
 	@Test
@@ -89,9 +86,10 @@ public class InvocableHandlerMethodTests {
 		addResolver(hm, Publishers.just("value1"));
 
 		Publisher<HandlerResult> publisher = hm.invokeForRequest(this.request);
-		Object value = awaitValue(publisher);
+		List<HandlerResult> values = Streams.wrap(publisher).toList().await(5, TimeUnit.SECONDS);
 
-		assertEquals("success:value1", value);
+		assertEquals(1, values.size());
+		assertEquals("success:value1", values.get(0).getValue());
 	}
 
 	@Test
@@ -100,12 +98,10 @@ public class InvocableHandlerMethodTests {
 		addResolver(hm, Publishers.from(Arrays.asList("value1", "value2", "value3")));
 
 		Publisher<HandlerResult> publisher = hm.invokeForRequest(this.request);
-		List<Signal<HandlerResult>> signals = awaitSignals(publisher);
+		List<HandlerResult> values = Streams.wrap(publisher).toList().await(5, TimeUnit.SECONDS);
 
-		assertEquals("Expected only one value: " + signals.toString(), 2, signals.size());
-		assertEquals(Signal.Type.NEXT, signals.get(0).getType());
-		assertEquals(Signal.Type.COMPLETE, signals.get(1).getType());
-		assertEquals("success:value1", signals.get(0).get().getValue());
+		assertEquals(1, values.size());
+		assertEquals("success:value1", values.get(0).getValue());
 	}
 
 	@Test
@@ -191,28 +187,10 @@ public class InvocableHandlerMethodTests {
 		handlerMethod.setHandlerMethodArgumentResolvers(Collections.singletonList(resolver));
 	}
 
-	private Object awaitValue(Publisher<HandlerResult> publisher) throws Exception {
-		Object object = awaitSignal(publisher, Signal.Type.NEXT).get();
-		assertEquals(HandlerResult.class, object.getClass());
-		return ((HandlerResult) object).getValue();
-	}
-
-	private Throwable awaitErrorSignal(Publisher<HandlerResult> publisher) throws Exception {
-		return awaitSignal(publisher, Signal.Type.ERROR).getThrowable();
-	}
-
-	@SuppressWarnings("unchecked")
-	private Signal<HandlerResult> awaitSignal(Publisher<HandlerResult> publisher, Signal.Type type) throws Exception {
-		Signal<HandlerResult> signal = awaitSignals(publisher).get(0);
-		if (!type.equals(signal.getType()) && signal.isOnError()) {
-			logger.error("Unexpected error: ", signal.getThrowable());
-		}
-		assertEquals("Unexpected signal: " + signal, type, signal.getType());
-		return signal;
-	}
-
-	private List<Signal<HandlerResult>> awaitSignals(Publisher<HandlerResult> publisher) throws InterruptedException {
-		return Streams.wrap(publisher).materialize().toList().await(5, TimeUnit.SECONDS);
+	private Throwable awaitErrorSignal(Publisher<?> publisher) throws Exception {
+		Signal<?> signal = Streams.wrap(publisher).materialize().toList().await(5, TimeUnit.SECONDS).get(0);
+		assertEquals("Unexpected signal: " + signal, Signal.Type.ERROR, signal.getType());
+		return signal.getThrowable();
 	}