org.springframework.http.codec.multipart.PartEventHttpMessageWriter Maven / Gradle / Ivy
/*
* Copyright 2002-2022 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
*
* https://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.codec.multipart;
import java.util.Collections;
import java.util.Map;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import org.springframework.core.ResolvableType;
import org.springframework.core.codec.Hints;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ReactiveHttpOutputMessage;
import org.springframework.http.codec.HttpMessageWriter;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* {@link HttpMessageWriter} for writing {@link PartEvent} objects. Useful for
* server-side proxies, that relay multipart requests to others services.
*
* @author Arjen Poutsma
* @since 6.0
* @see PartEvent
*/
public class PartEventHttpMessageWriter extends MultipartWriterSupport implements HttpMessageWriter {
public PartEventHttpMessageWriter() {
super(Collections.singletonList(MediaType.MULTIPART_FORM_DATA));
}
@Override
public boolean canWrite(ResolvableType elementType, @Nullable MediaType mediaType) {
if (PartEvent.class.isAssignableFrom(elementType.toClass())) {
if (mediaType == null) {
return true;
}
for (MediaType supportedMediaType : getWritableMediaTypes()) {
if (supportedMediaType.isCompatibleWith(mediaType)) {
return true;
}
}
}
return false;
}
@Override
public Mono write(Publisher partDataStream, ResolvableType elementType,
@Nullable MediaType mediaType, ReactiveHttpOutputMessage outputMessage,
Map hints) {
byte[] boundary = generateMultipartBoundary();
mediaType = getMultipartMediaType(mediaType, boundary);
outputMessage.getHeaders().setContentType(mediaType);
if (logger.isDebugEnabled()) {
logger.debug(Hints.getLogPrefix(hints) + "Encoding Publisher");
}
Flux body = Flux.from(partDataStream)
.windowUntil(PartEvent::isLast)
.concatMap(partData -> partData.switchOnFirst((signal, flux) -> {
if (signal.hasValue()) {
PartEvent value = signal.get();
Assert.state(value != null, "Null value");
Flux dataBuffers = flux.map(PartEvent::content)
.filter(buffer -> buffer.readableByteCount() > 0);
return encodePartData(boundary, outputMessage.bufferFactory(), value.headers(), dataBuffers);
}
else {
return flux.cast(DataBuffer.class);
}
}))
.concatWith(generateLastLine(boundary, outputMessage.bufferFactory()))
.doOnDiscard(DataBuffer.class, DataBufferUtils::release);
if (logger.isDebugEnabled()) {
body = body.doOnNext(buffer -> Hints.touchDataBuffer(buffer, hints, logger));
}
return outputMessage.writeWith(body);
}
private Flux encodePartData(byte[] boundary, DataBufferFactory bufferFactory, HttpHeaders headers, Flux body) {
return Flux.concat(
generateBoundaryLine(boundary, bufferFactory),
generatePartHeaders(headers, bufferFactory),
body,
generateNewLine(bufferFactory));
}
}