001/*
002 * Copyright 2002-2017 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.messaging.converter;
018
019import org.springframework.lang.Nullable;
020import org.springframework.messaging.MessageHeaders;
021import org.springframework.util.MimeType;
022
023/**
024 * A default {@link ContentTypeResolver} that checks the
025 * {@link MessageHeaders#CONTENT_TYPE} header or falls back to a default value.
026 *
027 * <p>The header value is expected to be a {@link org.springframework.util.MimeType}
028 * or a {@code String} that can be parsed into a {@code MimeType}.
029 *
030 * @author Rossen Stoyanchev
031 * @since 4.0
032 */
033public class DefaultContentTypeResolver implements ContentTypeResolver {
034
035        @Nullable
036        private MimeType defaultMimeType;
037
038
039        /**
040         * Set the default MIME type to use when there is no
041         * {@link MessageHeaders#CONTENT_TYPE} header present.
042         * <p>This property does not have a default value.
043         */
044        public void setDefaultMimeType(@Nullable MimeType defaultMimeType) {
045                this.defaultMimeType = defaultMimeType;
046        }
047
048        /**
049         * Return the default MIME type to use if no
050         * {@link MessageHeaders#CONTENT_TYPE} header is present.
051         */
052        @Nullable
053        public MimeType getDefaultMimeType() {
054                return this.defaultMimeType;
055        }
056
057
058        @Override
059        @Nullable
060        public MimeType resolve(@Nullable MessageHeaders headers) {
061                if (headers == null || headers.get(MessageHeaders.CONTENT_TYPE) == null) {
062                        return this.defaultMimeType;
063                }
064                Object value = headers.get(MessageHeaders.CONTENT_TYPE);
065                if (value == null) {
066                        return null;
067                }
068                else if (value instanceof MimeType) {
069                        return (MimeType) value;
070                }
071                else if (value instanceof String) {
072                        return MimeType.valueOf((String) value);
073                }
074                else {
075                        throw new IllegalArgumentException(
076                                        "Unknown type for contentType header value: " + value.getClass());
077                }
078        }
079
080        @Override
081        public String toString() {
082                return "DefaultContentTypeResolver[" + "defaultMimeType=" + this.defaultMimeType + "]";
083        }
084
085}