Support returning Observable from Spring MVC Controllers.

Via spring 4.2 new AsyncHandlerMethodReturnValueHandler

fixes gh-231

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/rx/ObservableReturnValueHandler.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2013-2015 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.cloud.netflix.rx;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.web.context.request.NativeWebRequest;
+import org.springframework.web.context.request.async.DeferredResult;
+import org.springframework.web.context.request.async.WebAsyncUtils;
+import org.springframework.web.method.support.AsyncHandlerMethodReturnValueHandler;
+import org.springframework.web.method.support.ModelAndViewContainer;
+import rx.Observable;
+import rx.functions.Action1;
+
+/**
+ * Handles return values of type {@link rx.Observable}.
+ *
+ * @author Spencer Gibb
+ */
+public class ObservableReturnValueHandler implements AsyncHandlerMethodReturnValueHandler {
+
+	@Override
+	public boolean isAsyncReturnValue(Object returnValue, MethodParameter returnType) {
+		return returnValue != null && returnValue instanceof Observable;
+	}
+
+	@Override
+	public boolean supportsReturnType(MethodParameter returnType) {
+		return Observable.class.isAssignableFrom(returnType.getParameterType());
+	}
+
+	@Override
+	public void handleReturnValue(Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
+		if (returnValue == null) {
+			mavContainer.setRequestHandled(true);
+			return;
+		}
+
+		Observable<?> observable = Observable.class.cast(returnValue);
+
+		final DeferredResult<Object> deferredResult = new DeferredResult<>();
+
+        observable.subscribe(new Action1<Object>() {
+            @Override
+            public void call(Object o) {
+                deferredResult.setResult(o);
+            }
+        }, new Action1<Throwable>() {
+            @Override
+            public void call(Throwable throwable) {
+                deferredResult.setErrorResult(throwable);
+            }
+        });
+
+		WebAsyncUtils.getAsyncManager(webRequest)
+				.startDeferredResultProcessing(deferredResult, mavContainer);
+	}
+}

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/rx/RxJavaAutoConfiguration.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2013-2015 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.cloud.netflix.rx;
+
+import java.util.List;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
+
+import rx.Observable;
+
+/**
+ * @author Spencer Gibb
+ */
+@Configuration
+@ConditionalOnClass(Observable.class)
+public class RxJavaAutoConfiguration {
+
+	@Bean
+	public ObservableReturnValueHandler observableReturnValueHandler() {
+		return new ObservableReturnValueHandler();
+	}
+
+	@Bean
+	@ConditionalOnWebApplication
+	public WebMvcConfigurerAdapter observableMVCConfiguration() {
+		return new WebMvcConfigurerAdapter() {
+			@Override
+			public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
+				returnValueHandlers.add(observableReturnValueHandler());
+			}
+		};
+	}
+}

spring-cloud-netflix-core/src/main/resources/META-INF/spring.factories

@@ -8,6 +8,7 @@ org.springframework.cloud.netflix.hystrix.HystrixAutoConfiguration,\
 org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration,\
 org.springframework.cloud.netflix.ribbon.RibbonAutoConfiguration,\
 org.springframework.cloud.netflix.ribbon.eureka.RibbonEurekaAutoConfiguration,\
+org.springframework.cloud.netflix.rx.RxJavaAutoConfiguration,\
 org.springframework.cloud.netflix.servo.ServoMetricsAutoConfiguration
 
 org.springframework.cloud.bootstrap.BootstrapConfiguration=\

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/rx/ObservableReturnValueHandlerTests.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2013-2015 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.cloud.netflix.rx;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.IntegrationTest;
+import org.springframework.boot.test.SpringApplicationConfiguration;
+import org.springframework.boot.test.TestRestTemplate;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RestController;
+
+import rx.Observable;
+
+/**
+ * @author Spencer Gibb
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = ObservableReturnValueHandlerTests.Application.class)
+@WebAppConfiguration
+@IntegrationTest({ "server.port=0" })
+@DirtiesContext
+public class ObservableReturnValueHandlerTests {
+
+	@Value("${local.server.port}")
+	private int port = 0;
+
+	@Configuration
+	@EnableAutoConfiguration
+	@RestController
+	protected static class Application {
+		@RequestMapping(method = RequestMethod.GET, value = "/")
+		public Observable<String> hi() {
+			return Observable.just("hello world");
+		}
+	}
+
+	@Test
+	public void observableReturns() {
+		ResponseEntity<String> response = new TestRestTemplate().getForEntity("http://localhost:" + port, String.class);
+		assertNotNull("response was null", response);
+		assertEquals("response code was wrong", HttpStatus.OK, response.getStatusCode());
+		assertEquals("response was wrong", "hello world", response.getBody());
+	}
+}