org.springframework.web.reactive.result.method.annotation.ResponseEntityResultHandler Maven / Gradle / Ivy
/*
* Copyright 2002-2018 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.reactive.result.method.annotation;
import java.time.Instant;
import java.util.EnumSet;
import java.util.List;
import java.util.Set;
import reactor.core.publisher.Mono;
import org.springframework.core.MethodParameter;
import org.springframework.core.ReactiveAdapter;
import org.springframework.core.ReactiveAdapterRegistry;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.HttpStatus;
import org.springframework.http.RequestEntity;
import org.springframework.http.ResponseEntity;
import org.springframework.http.codec.HttpMessageWriter;
import org.springframework.http.server.reactive.AbstractServerHttpResponse;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.reactive.HandlerResult;
import org.springframework.web.reactive.HandlerResultHandler;
import org.springframework.web.reactive.accept.RequestedContentTypeResolver;
import org.springframework.web.server.ServerWebExchange;
/**
* Handles {@link HttpEntity} and {@link ResponseEntity} return values.
*
* By default the order for this result handler is set to 0. It is generally
* safe to place it early in the order as it looks for a concrete return type.
*
* @author Rossen Stoyanchev
* @since 5.0
*/
public class ResponseEntityResultHandler extends AbstractMessageWriterResultHandler implements HandlerResultHandler {
private static final Set SAFE_METHODS = EnumSet.of(HttpMethod.GET, HttpMethod.HEAD);
/**
* Basic constructor with a default {@link ReactiveAdapterRegistry}.
* @param writers writers for serializing to the response body
* @param resolver to determine the requested content type
*/
public ResponseEntityResultHandler(List> writers,
RequestedContentTypeResolver resolver) {
this(writers, resolver, ReactiveAdapterRegistry.getSharedInstance());
}
/**
* Constructor with an {@link ReactiveAdapterRegistry} instance.
* @param writers writers for serializing to the response body
* @param resolver to determine the requested content type
* @param registry for adaptation to reactive types
*/
public ResponseEntityResultHandler(List> writers,
RequestedContentTypeResolver resolver, ReactiveAdapterRegistry registry) {
super(writers, resolver, registry);
setOrder(0);
}
@Override
public boolean supports(HandlerResult result) {
Class valueType = resolveReturnValueType(result);
if (isSupportedType(valueType)) {
return true;
}
ReactiveAdapter adapter = getAdapter(result);
return adapter != null && !adapter.isNoValue() &&
isSupportedType(result.getReturnType().getGeneric().toClass());
}
@Nullable
private static Class resolveReturnValueType(HandlerResult result) {
Class valueType = result.getReturnType().toClass();
Object value = result.getReturnValue();
if (valueType == Object.class && value != null) {
valueType = value.getClass();
}
return valueType;
}
private boolean isSupportedType(@Nullable Class clazz) {
return (clazz != null && ((HttpEntity.class.isAssignableFrom(clazz) &&
!RequestEntity.class.isAssignableFrom(clazz)) ||
HttpHeaders.class.isAssignableFrom(clazz)));
}
@Override
public Mono handleResult(ServerWebExchange exchange, HandlerResult result) {
Mono returnValueMono;
MethodParameter bodyParameter;
ReactiveAdapter adapter = getAdapter(result);
MethodParameter actualParameter = result.getReturnTypeSource();
if (adapter != null) {
Assert.isTrue(!adapter.isMultiValue(), "Only a single ResponseEntity supported");
returnValueMono = Mono.from(adapter.toPublisher(result.getReturnValue()));
bodyParameter = actualParameter.nested().nested();
}
else {
returnValueMono = Mono.justOrEmpty(result.getReturnValue());
bodyParameter = actualParameter.nested();
}
return returnValueMono.flatMap(returnValue -> {
HttpEntity httpEntity;
if (returnValue instanceof HttpEntity) {
httpEntity = (HttpEntity) returnValue;
}
else if (returnValue instanceof HttpHeaders) {
httpEntity = new ResponseEntity<>((HttpHeaders) returnValue, HttpStatus.OK);
}
else {
throw new IllegalArgumentException(
"HttpEntity or HttpHeaders expected but got: " + returnValue.getClass());
}
if (httpEntity instanceof ResponseEntity) {
ResponseEntity responseEntity = (ResponseEntity) httpEntity;
ServerHttpResponse response = exchange.getResponse();
if (response instanceof AbstractServerHttpResponse) {
((AbstractServerHttpResponse) response).setStatusCodeValue(responseEntity.getStatusCodeValue());
}
else {
response.setStatusCode(responseEntity.getStatusCode());
}
}
HttpHeaders entityHeaders = httpEntity.getHeaders();
HttpHeaders responseHeaders = exchange.getResponse().getHeaders();
if (!entityHeaders.isEmpty()) {
entityHeaders.entrySet().stream()
.forEach(entry -> responseHeaders.put(entry.getKey(), entry.getValue()));
}
if (httpEntity.getBody() == null || returnValue instanceof HttpHeaders) {
return exchange.getResponse().setComplete();
}
String etag = entityHeaders.getETag();
Instant lastModified = Instant.ofEpochMilli(entityHeaders.getLastModified());
HttpMethod httpMethod = exchange.getRequest().getMethod();
if (SAFE_METHODS.contains(httpMethod) && exchange.checkNotModified(etag, lastModified)) {
return exchange.getResponse().setComplete();
}
return writeBody(httpEntity.getBody(), bodyParameter, actualParameter, exchange);
});
}
}