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.http.codec;
018
019import java.util.List;
020import java.util.Map;
021
022import org.apache.commons.logging.Log;
023import reactor.core.publisher.Flux;
024import reactor.core.publisher.Mono;
025
026import org.springframework.core.ResolvableType;
027import org.springframework.core.codec.AbstractDecoder;
028import org.springframework.core.codec.Decoder;
029import org.springframework.core.codec.Hints;
030import org.springframework.http.HttpLogging;
031import org.springframework.http.HttpMessage;
032import org.springframework.http.MediaType;
033import org.springframework.http.ReactiveHttpInputMessage;
034import org.springframework.http.server.reactive.ServerHttpRequest;
035import org.springframework.http.server.reactive.ServerHttpResponse;
036import org.springframework.lang.Nullable;
037import org.springframework.util.Assert;
038
039/**
040 * {@code HttpMessageReader} that wraps and delegates to a {@link Decoder}.
041 *
042 * <p>Also a {@code HttpMessageReader} that pre-resolves decoding hints
043 * from the extra information available on the server side such as the request
044 * or controller method parameter annotations.
045 *
046 * @author Arjen Poutsma
047 * @author Sebastien Deleuze
048 * @author Rossen Stoyanchev
049 * @since 5.0
050 * @param <T> the type of objects in the decoded output stream
051 */
052public class DecoderHttpMessageReader<T> implements HttpMessageReader<T> {
053
054        private final Decoder<T> decoder;
055
056        private final List<MediaType> mediaTypes;
057
058
059        /**
060         * Create an instance wrapping the given {@link Decoder}.
061         */
062        public DecoderHttpMessageReader(Decoder<T> decoder) {
063                Assert.notNull(decoder, "Decoder is required");
064                initLogger(decoder);
065                this.decoder = decoder;
066                this.mediaTypes = MediaType.asMediaTypes(decoder.getDecodableMimeTypes());
067        }
068
069        private static void initLogger(Decoder<?> decoder) {
070                if (decoder instanceof AbstractDecoder &&
071                                decoder.getClass().getName().startsWith("org.springframework.core.codec")) {
072                        Log logger = HttpLogging.forLog(((AbstractDecoder<?>) decoder).getLogger());
073                        ((AbstractDecoder<?>) decoder).setLogger(logger);
074                }
075        }
076
077
078        /**
079         * Return the {@link Decoder} of this reader.
080         */
081        public Decoder<T> getDecoder() {
082                return this.decoder;
083        }
084
085        @Override
086        public List<MediaType> getReadableMediaTypes() {
087                return this.mediaTypes;
088        }
089
090
091        @Override
092        public boolean canRead(ResolvableType elementType, @Nullable MediaType mediaType) {
093                return this.decoder.canDecode(elementType, mediaType);
094        }
095
096        @Override
097        public Flux<T> read(ResolvableType elementType, ReactiveHttpInputMessage message, Map<String, Object> hints) {
098                MediaType contentType = getContentType(message);
099                return this.decoder.decode(message.getBody(), elementType, contentType, hints);
100        }
101
102        @Override
103        public Mono<T> readMono(ResolvableType elementType, ReactiveHttpInputMessage message, Map<String, Object> hints) {
104                MediaType contentType = getContentType(message);
105                return this.decoder.decodeToMono(message.getBody(), elementType, contentType, hints);
106        }
107
108        /**
109         * Determine the Content-Type of the HTTP message based on the
110         * "Content-Type" header or otherwise default to
111         * {@link MediaType#APPLICATION_OCTET_STREAM}.
112         * @param inputMessage the HTTP message
113         * @return the MediaType, possibly {@code null}.
114         */
115        @Nullable
116        protected MediaType getContentType(HttpMessage inputMessage) {
117                MediaType contentType = inputMessage.getHeaders().getContentType();
118                return (contentType != null ? contentType : MediaType.APPLICATION_OCTET_STREAM);
119        }
120
121
122        // Server-side only...
123
124        @Override
125        public Flux<T> read(ResolvableType actualType, ResolvableType elementType,
126                        ServerHttpRequest request, ServerHttpResponse response, Map<String, Object> hints) {
127
128                Map<String, Object> allHints = Hints.merge(hints,
129                                getReadHints(actualType, elementType, request, response));
130
131                return read(elementType, request, allHints);
132        }
133
134        @Override
135        public Mono<T> readMono(ResolvableType actualType, ResolvableType elementType,
136                        ServerHttpRequest request, ServerHttpResponse response, Map<String, Object> hints) {
137
138                Map<String, Object> allHints = Hints.merge(hints,
139                                getReadHints(actualType, elementType, request, response));
140
141                return readMono(elementType, request, allHints);
142        }
143
144        /**
145         * Get additional hints for decoding for example based on the server request
146         * or annotations from controller method parameters. By default, delegate to
147         * the decoder if it is an instance of {@link HttpMessageDecoder}.
148         */
149        protected Map<String, Object> getReadHints(ResolvableType actualType,
150                        ResolvableType elementType, ServerHttpRequest request, ServerHttpResponse response) {
151
152                if (this.decoder instanceof HttpMessageDecoder) {
153                        HttpMessageDecoder<?> decoder = (HttpMessageDecoder<?>) this.decoder;
154                        return decoder.getDecodeHints(actualType, elementType, request, response);
155                }
156                return Hints.none();
157        }
158
159}