001/*
002 * Copyright 2002-2019 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.core.codec;
018
019import java.util.Map;
020
021import reactor.core.publisher.Flux;
022
023import org.springframework.core.ResolvableType;
024import org.springframework.core.io.Resource;
025import org.springframework.core.io.buffer.DataBuffer;
026import org.springframework.core.io.buffer.DataBufferFactory;
027import org.springframework.core.io.buffer.DataBufferUtils;
028import org.springframework.lang.Nullable;
029import org.springframework.util.Assert;
030import org.springframework.util.MimeType;
031import org.springframework.util.MimeTypeUtils;
032import org.springframework.util.StreamUtils;
033
034/**
035 * Encoder for {@link Resource Resources}.
036 *
037 * @author Arjen Poutsma
038 * @since 5.0
039 */
040public class ResourceEncoder extends AbstractSingleValueEncoder<Resource> {
041
042        /**
043         * The default buffer size used by the encoder.
044         */
045        public static final int DEFAULT_BUFFER_SIZE = StreamUtils.BUFFER_SIZE;
046
047        private final int bufferSize;
048
049
050        public ResourceEncoder() {
051                this(DEFAULT_BUFFER_SIZE);
052        }
053
054        public ResourceEncoder(int bufferSize) {
055                super(MimeTypeUtils.APPLICATION_OCTET_STREAM, MimeTypeUtils.ALL);
056                Assert.isTrue(bufferSize > 0, "'bufferSize' must be larger than 0");
057                this.bufferSize = bufferSize;
058        }
059
060
061        @Override
062        public boolean canEncode(ResolvableType elementType, @Nullable MimeType mimeType) {
063                Class<?> clazz = elementType.toClass();
064                return (super.canEncode(elementType, mimeType) && Resource.class.isAssignableFrom(clazz));
065        }
066
067        @Override
068        protected Flux<DataBuffer> encode(Resource resource, DataBufferFactory bufferFactory,
069                        ResolvableType type, @Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
070
071                if (logger.isDebugEnabled() && !Hints.isLoggingSuppressed(hints)) {
072                        String logPrefix = Hints.getLogPrefix(hints);
073                        logger.debug(logPrefix + "Writing [" + resource + "]");
074                }
075                return DataBufferUtils.read(resource, bufferFactory, this.bufferSize);
076        }
077
078}