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/*
* Copyright 2002-2019 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.core.codec;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
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.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.MimeType;
import org.springframework.util.MimeTypeUtils;
import org.springframework.util.StreamUtils;
/**
* Encoder for {@link ResourceRegion ResourceRegions}.
*
* @author Brian Clozel
* @since 5.0
*/
public class ResourceRegionEncoder extends AbstractEncoder {
/**
* The default buffer size used by the encoder.
*/
public static final int DEFAULT_BUFFER_SIZE = StreamUtils.BUFFER_SIZE;
/**
* The hint key that contains the boundary string.
*/
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, @Nullable MimeType mimeType) {
return super.canEncode(elementType, mimeType)
&& ResourceRegion.class.isAssignableFrom(elementType.toClass());
}
@Override
public Flux encode(Publisher input,
DataBufferFactory bufferFactory, ResolvableType elementType, @Nullable MimeType mimeType,
@Nullable Map hints) {
Assert.notNull(input, "'inputStream' must not be null");
Assert.notNull(bufferFactory, "'bufferFactory' must not be null");
Assert.notNull(elementType, "'elementType' must not be null");
if (input instanceof Mono) {
return Mono.from(input)
.flatMapMany(region -> {
if (!region.getResource().isReadable()) {
return Flux.error(new EncodingException(
"Resource " + region.getResource() + " is not readable"));
}
return writeResourceRegion(region, bufferFactory, hints);
});
}
else {
final String boundaryString = Hints.getRequiredHint(hints, BOUNDARY_STRING_HINT);
byte[] startBoundary = toAsciiBytes("\r\n--" + boundaryString + "\r\n");
byte[] contentType = mimeType != null ? toAsciiBytes("Content-Type: " + mimeType + "\r\n") : new byte[0];
return Flux.from(input)
.concatMap(region -> {
if (!region.getResource().isReadable()) {
return Flux.error(new EncodingException(
"Resource " + region.getResource() + " is not readable"));
}
Flux prefix = Flux.just(
bufferFactory.wrap(startBoundary),
bufferFactory.wrap(contentType),
bufferFactory.wrap(getContentRangeHeader(region))); // only wrapping, no allocation
return prefix.concatWith(writeResourceRegion(region, bufferFactory, hints));
})
.concatWithValues(getRegionSuffix(bufferFactory, boundaryString));
}
// No doOnDiscard (no caching after DataBufferUtils#read)
}
private Flux writeResourceRegion(
ResourceRegion region, DataBufferFactory bufferFactory, @Nullable Map hints) {
Resource resource = region.getResource();
long position = region.getPosition();
long count = region.getCount();
if (logger.isDebugEnabled() && !Hints.isLoggingSuppressed(hints)) {
logger.debug(Hints.getLogPrefix(hints) +
"Writing region " + position + "-" + (position + count) + " of [" + resource + "]");
}
Flux in = DataBufferUtils.read(resource, position, bufferFactory, this.bufferSize);
return DataBufferUtils.takeUntilByteCount(in, count);
}
private DataBuffer getRegionSuffix(DataBufferFactory bufferFactory, String boundaryString) {
byte[] endBoundary = toAsciiBytes("\r\n--" + boundaryString + "--");
return bufferFactory.wrap(endBoundary);
}
private byte[] toAsciiBytes(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()) {
long length = contentLength.getAsLong();
return toAsciiBytes("Content-Range: bytes " + start + '-' + end + '/' + length + "\r\n\r\n");
}
else {
return toAsciiBytes("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();
}
}
