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/*
* Copyright 2002-2016 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.servlet.mvc.method.annotation;
import java.util.concurrent.CompletionStage;
import java.util.function.Consumer;
import java.util.function.Function;
import org.springframework.core.MethodParameter;
import org.springframework.lang.UsesJava8;
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;
/**
* Handles return values of type {@link CompletionStage} (implemented by
* {@link java.util.concurrent.CompletableFuture} for example).
*
* @author Sebastien Deleuze
* @since 4.2
* @deprecated as of 4.3 {@link DeferredResultMethodReturnValueHandler} supports
* CompletionStage return values via an adapter mechanism.
*/
@Deprecated
@UsesJava8
public class CompletionStageReturnValueHandler implements AsyncHandlerMethodReturnValueHandler {
@Override
public boolean supportsReturnType(MethodParameter returnType) {
return CompletionStage.class.isAssignableFrom(returnType.getParameterType());
}
@Override
public boolean isAsyncReturnValue(Object returnValue, MethodParameter returnType) {
return (returnValue != null && returnValue instanceof CompletionStage);
}
@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<Object>();
WebAsyncUtils.getAsyncManager(webRequest).startDeferredResultProcessing(deferredResult, mavContainer);
@SuppressWarnings("unchecked")
CompletionStage<Object> future = (CompletionStage<Object>) returnValue;
future.thenAccept(new Consumer<Object>() {
@Override
public void accept(Object result) {
deferredResult.setResult(result);
}
});
future.exceptionally(new Function<Throwable, Object>() {
@Override
public Object apply(Throwable ex) {
deferredResult.setErrorResult(ex);
return null;
}
});
}
}
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