Java tutorial
package com.kixeye.chassis.transport.http; /* * #%L * Chassis Transport Core * %% * Copyright (C) 2014 KIXEYE, Inc * %% * 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. * #L% */ import com.google.common.util.concurrent.FutureCallback; import com.google.common.util.concurrent.Futures; import com.google.common.util.concurrent.ListenableFuture; 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.HandlerMethodReturnValueHandler; import org.springframework.web.method.support.ModelAndViewContainer; import javax.annotation.Nullable; public class ListenableFutureReturnValueHandler implements HandlerMethodReturnValueHandler { @Override public boolean supportsReturnType(MethodParameter returnType) { Class<?> clazz = returnType.getParameterType(); return ListenableFuture.class.isAssignableFrom(clazz); } @Override public void handleReturnValue(Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception { if (returnValue == null) { mavContainer.setRequestHandled(true); return; } final DeferredResult<Object> deferredResult = new DeferredResult<>(); Futures.addCallback((ListenableFuture<?>) returnValue, new FutureCallback<Object>() { @Override public void onSuccess(@Nullable Object result) { deferredResult.setResult(result); } @Override public void onFailure(Throwable t) { deferredResult.setErrorResult(t); } }); WebAsyncUtils.getAsyncManager(webRequest).startDeferredResultProcessing(deferredResult, mavContainer); } }