/*
* Copyright 2002-2017 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.core.codec;
import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousFileChannel;
import java.nio.channels.ReadableByteChannel;
import java.nio.charset.StandardCharsets;
import java.nio.file.StandardOpenOption;
import java.util.Map;
import java.util.OptionalLong;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import org.springframework.core.ResolvableType;
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.buffer.DataBufferUtils;
import org.springframework.core.io.support.ResourceRegion;
import org.springframework.util.Assert;
import org.springframework.util.MimeType;
import org.springframework.util.MimeTypeUtils;
import org.springframework.util.StreamUtils;
/**
* Encoder for {@link ResourceRegion}s.
*
* @author Brian Clozel
* @since 5.0
*/
public class ResourceRegionEncoder extends AbstractEncoder<ResourceRegion> {
public static final int DEFAULT_BUFFER_SIZE = StreamUtils.BUFFER_SIZE;
public static final String BOUNDARY_STRING_HINT = ResourceRegionEncoder.class.getName() + ".boundaryString";
private final int bufferSize;
public ResourceRegionEncoder() {
this(DEFAULT_BUFFER_SIZE);
}
public ResourceRegionEncoder(int bufferSize) {
super(MimeTypeUtils.APPLICATION_OCTET_STREAM, MimeTypeUtils.ALL);
Assert.isTrue(bufferSize > 0, "'bufferSize' must be larger than 0");
this.bufferSize = bufferSize;
}
@Override
public boolean canEncode(ResolvableType elementType, MimeType mimeType) {
return super.canEncode(elementType, mimeType)
&& ResourceRegion.class.isAssignableFrom(elementType.resolve(Object.class));
}
@Override
@SuppressWarnings("unchecked")
public Flux<DataBuffer> encode(Publisher<? extends ResourceRegion> inputStream,
DataBufferFactory bufferFactory, ResolvableType elementType, MimeType mimeType, Map<String, Object> hints) {
Assert.notNull(inputStream, "'inputStream' must not be null");
Assert.notNull(bufferFactory, "'bufferFactory' must not be null");
Assert.notNull(elementType, "'elementType' must not be null");
if (inputStream instanceof Mono) {
return ((Mono<? extends ResourceRegion>) inputStream)
.flatMapMany(region -> writeResourceRegion(region, bufferFactory));
}
else {
Assert.notNull(hints, "'hints' must not be null");
Assert.isTrue(hints.containsKey(BOUNDARY_STRING_HINT), "'hints' must contain boundaryString hint");
final String boundaryString = (String) hints.get(BOUNDARY_STRING_HINT);
byte[] startBoundary = getAsciiBytes("\r\n--" + boundaryString + "\r\n");
byte[] contentType = getAsciiBytes("Content-Type: " + mimeType.toString() + "\r\n");
Flux<DataBuffer> regions = Flux.from(inputStream).
concatMap(region ->
Flux.concat(
getRegionPrefix(bufferFactory, startBoundary, contentType, region),
writeResourceRegion(region, bufferFactory)
));
return Flux.concat(regions, getRegionSuffix(bufferFactory, boundaryString));
}
}
private Flux<DataBuffer> getRegionPrefix(DataBufferFactory bufferFactory, byte[] startBoundary,
byte[] contentType, ResourceRegion region) {
return Flux.just(
bufferFactory.allocateBuffer(startBoundary.length).write(startBoundary),
bufferFactory.allocateBuffer(contentType.length).write(contentType),
bufferFactory.wrap(ByteBuffer.wrap(getContentRangeHeader(region)))
);
}
private Flux<DataBuffer> writeResourceRegion(ResourceRegion region, DataBufferFactory bufferFactory) {
Flux<DataBuffer> in = readResourceRegion(region, bufferFactory);
return DataBufferUtils.takeUntilByteCount(in, region.getCount());
}
private Flux<DataBuffer> readResourceRegion(ResourceRegion region, DataBufferFactory bufferFactory) {
Resource resource = region.getResource();
try {
if (resource.isFile()) {
File file = region.getResource().getFile();
AsynchronousFileChannel channel =
AsynchronousFileChannel.open(file.toPath(), StandardOpenOption.READ);
return DataBufferUtils.read(channel, region.getPosition(),
bufferFactory, this.bufferSize);
}
}
catch (IOException ignore) {
// fallback to resource.readableChannel(), below
}
try {
ReadableByteChannel channel = resource.readableChannel();
Flux<DataBuffer> in = DataBufferUtils.read(channel, bufferFactory, this.bufferSize);
return DataBufferUtils.skipUntilByteCount(in, region.getPosition());
}
catch (IOException ex) {
return Flux.error(ex);
}
}
private Flux<DataBuffer> getRegionSuffix(DataBufferFactory bufferFactory, String boundaryString) {
byte[] endBoundary = getAsciiBytes("\r\n--" + boundaryString + "--");
return Flux.just(bufferFactory.allocateBuffer(endBoundary.length).write(endBoundary));
}
private byte[] getAsciiBytes(String in) {
return in.getBytes(StandardCharsets.US_ASCII);
}
private byte[] getContentRangeHeader(ResourceRegion region) {
long start = region.getPosition();
long end = start + region.getCount() - 1;
OptionalLong contentLength = contentLength(region.getResource());
if (contentLength.isPresent()) {
return getAsciiBytes("Content-Range: bytes " + start + '-' + end + '/' + contentLength.getAsLong() + "\r\n\r\n");
}
else {
return getAsciiBytes("Content-Range: bytes " + start + '-' + end + "\r\n\r\n");
}
}
/**
* Determine, if possible, the contentLength of the given resource without reading it.
* @param resource the resource instance
* @return the contentLength of the resource
*/
private OptionalLong contentLength(Resource resource) {
// Don't try to determine contentLength on InputStreamResource - cannot be read afterwards...
// Note: custom InputStreamResource subclasses could provide a pre-calculated content length!
if (InputStreamResource.class != resource.getClass()) {
try {
return OptionalLong.of(resource.contentLength());
}
catch (IOException ignored) {
}
}
return OptionalLong.empty();
}
}