/*
 * 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.http.codec;

import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.Optional;

import org.apache.commons.logging.Log;
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.codec.ResourceDecoder;
import org.springframework.core.codec.ResourceEncoder;
import org.springframework.core.codec.ResourceRegionEncoder;
import org.springframework.core.io.InputStreamResource;
import org.springframework.core.io.Resource;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.support.ResourceRegion;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpLogging;
import org.springframework.http.HttpRange;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.MediaTypeFactory;
import org.springframework.http.ReactiveHttpOutputMessage;
import org.springframework.http.ZeroCopyHttpOutputMessage;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.lang.Nullable;
import org.springframework.util.MimeTypeUtils;

HttpMessageWriter that can write a Resource.

Also an implementation of HttpMessageWriter with support for writing one or more ResourceRegion's based on the HTTP ranges specified in the request.

For reading to a Resource, use ResourceDecoder wrapped with DecoderHttpMessageReader.

Author:Arjen Poutsma, Brian Clozel, Rossen Stoyanchev
See Also:
Since:5.0
/** * {@code HttpMessageWriter} that can write a {@link Resource}. * * <p>Also an implementation of {@code HttpMessageWriter} with support * for writing one or more {@link ResourceRegion}'s based on the HTTP ranges * specified in the request. * * <p>For reading to a Resource, use {@link ResourceDecoder} wrapped with * {@link DecoderHttpMessageReader}. * * @author Arjen Poutsma * @author Brian Clozel * @author Rossen Stoyanchev * @since 5.0 * @see ResourceEncoder * @see ResourceRegionEncoder * @see HttpRange */
public class ResourceHttpMessageWriter implements HttpMessageWriter<Resource> { private static final ResolvableType REGION_TYPE = ResolvableType.forClass(ResourceRegion.class); private static final Log logger = HttpLogging.forLogName(ResourceHttpMessageWriter.class); private final ResourceEncoder encoder; private final ResourceRegionEncoder regionEncoder; private final List<MediaType> mediaTypes; public ResourceHttpMessageWriter() { this(ResourceEncoder.DEFAULT_BUFFER_SIZE); } public ResourceHttpMessageWriter(int bufferSize) { this.encoder = new ResourceEncoder(bufferSize); this.regionEncoder = new ResourceRegionEncoder(bufferSize); this.mediaTypes = MediaType.asMediaTypes(this.encoder.getEncodableMimeTypes()); } @Override public boolean canWrite(ResolvableType elementType, @Nullable MediaType mediaType) { return this.encoder.canEncode(elementType, mediaType); } @Override public List<MediaType> getWritableMediaTypes() { return this.mediaTypes; } // Client or server: single Resource... @Override public Mono<Void> write(Publisher<? extends Resource> inputStream, ResolvableType elementType, @Nullable MediaType mediaType, ReactiveHttpOutputMessage message, Map<String, Object> hints) { return Mono.from(inputStream).flatMap(resource -> writeResource(resource, elementType, mediaType, message, hints)); } private Mono<Void> writeResource(Resource resource, ResolvableType type, @Nullable MediaType mediaType, ReactiveHttpOutputMessage message, Map<String, Object> hints) { HttpHeaders headers = message.getHeaders(); MediaType resourceMediaType = getResourceMediaType(mediaType, resource, hints); headers.setContentType(resourceMediaType); if (headers.getContentLength() < 0) { long length = lengthOf(resource); if (length != -1) { headers.setContentLength(length); } } return zeroCopy(resource, null, message, hints) .orElseGet(() -> { Mono<Resource> input = Mono.just(resource); DataBufferFactory factory = message.bufferFactory(); Flux<DataBuffer> body = this.encoder.encode(input, factory, type, resourceMediaType, hints); return message.writeWith(body); }); } private static MediaType getResourceMediaType( @Nullable MediaType mediaType, Resource resource, Map<String, Object> hints) { if (mediaType != null && mediaType.isConcrete() && !mediaType.equals(MediaType.APPLICATION_OCTET_STREAM)) { return mediaType; } mediaType = MediaTypeFactory.getMediaType(resource).orElse(MediaType.APPLICATION_OCTET_STREAM); if (logger.isDebugEnabled() && !Hints.isLoggingSuppressed(hints)) { logger.debug(Hints.getLogPrefix(hints) + "Resource associated with '" + mediaType + "'"); } return mediaType; } private static long lengthOf(Resource resource) { // Don't consume InputStream... if (InputStreamResource.class != resource.getClass()) { try { return resource.contentLength(); } catch (IOException ignored) { } } return -1; } private static Optional<Mono<Void>> zeroCopy(Resource resource, @Nullable ResourceRegion region, ReactiveHttpOutputMessage message, Map<String, Object> hints) { if (message instanceof ZeroCopyHttpOutputMessage && resource.isFile()) { try { File file = resource.getFile(); long pos = region != null ? region.getPosition() : 0; long count = region != null ? region.getCount() : file.length(); if (logger.isDebugEnabled()) { String formatted = region != null ? "region " + pos + "-" + (count) + " of " : ""; logger.debug(Hints.getLogPrefix(hints) + "Zero-copy " + formatted + "[" + resource + "]"); } return Optional.of(((ZeroCopyHttpOutputMessage) message).writeWith(file, pos, count)); } catch (IOException ex) { // should not happen } } return Optional.empty(); } // Server-side only: single Resource or sub-regions... @Override @SuppressWarnings("unchecked") public Mono<Void> write(Publisher<? extends Resource> inputStream, @Nullable ResolvableType actualType, ResolvableType elementType, @Nullable MediaType mediaType, ServerHttpRequest request, ServerHttpResponse response, Map<String, Object> hints) { HttpHeaders headers = response.getHeaders(); headers.set(HttpHeaders.ACCEPT_RANGES, "bytes"); List<HttpRange> ranges; try { ranges = request.getHeaders().getRange(); } catch (IllegalArgumentException ex) { response.setStatusCode(HttpStatus.REQUESTED_RANGE_NOT_SATISFIABLE); return response.setComplete(); } return Mono.from(inputStream).flatMap(resource -> { if (ranges.isEmpty()) { return writeResource(resource, elementType, mediaType, response, hints); } response.setStatusCode(HttpStatus.PARTIAL_CONTENT); List<ResourceRegion> regions = HttpRange.toResourceRegions(ranges, resource); MediaType resourceMediaType = getResourceMediaType(mediaType, resource, hints); if (regions.size() == 1){ ResourceRegion region = regions.get(0); headers.setContentType(resourceMediaType); long contentLength = lengthOf(resource); if (contentLength != -1) { long start = region.getPosition(); long end = start + region.getCount() - 1; end = Math.min(end, contentLength - 1); headers.add("Content-Range", "bytes " + start + '-' + end + '/' + contentLength); headers.setContentLength(end - start + 1); } return writeSingleRegion(region, response, hints); } else { String boundary = MimeTypeUtils.generateMultipartBoundaryString(); MediaType multipartType = MediaType.parseMediaType("multipart/byteranges;boundary=" + boundary); headers.setContentType(multipartType); Map<String, Object> allHints = Hints.merge(hints, ResourceRegionEncoder.BOUNDARY_STRING_HINT, boundary); return encodeAndWriteRegions(Flux.fromIterable(regions), resourceMediaType, response, allHints); } }); } private Mono<Void> writeSingleRegion(ResourceRegion region, ReactiveHttpOutputMessage message, Map<String, Object> hints) { return zeroCopy(region.getResource(), region, message, hints) .orElseGet(() -> { Publisher<? extends ResourceRegion> input = Mono.just(region); MediaType mediaType = message.getHeaders().getContentType(); return encodeAndWriteRegions(input, mediaType, message, hints); }); } private Mono<Void> encodeAndWriteRegions(Publisher<? extends ResourceRegion> publisher, @Nullable MediaType mediaType, ReactiveHttpOutputMessage message, Map<String, Object> hints) { Flux<DataBuffer> body = this.regionEncoder.encode( publisher, message.bufferFactory(), REGION_TYPE, mediaType, hints); return message.writeWith(body); } }