Add HttpExceptionHandler

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

@@ -0,0 +1,73 @@
+/*
+ * 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

@@ -0,0 +1,43 @@
+/*
+ * 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);
+
+}