001/*
002 * Copyright 2002-2014 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.web.servlet.mvc.method.annotation;
018
019import org.springframework.core.MethodParameter;
020import org.springframework.http.MediaType;
021import org.springframework.http.converter.HttpMessageConverter;
022import org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter;
023import org.springframework.http.converter.json.MappingJacksonValue;
024import org.springframework.http.server.ServerHttpRequest;
025import org.springframework.http.server.ServerHttpResponse;
026
027/**
028 * A convenient base class for {@code ResponseBodyAdvice} implementations
029 * that customize the response before JSON serialization with
030 * {@link AbstractJackson2HttpMessageConverter}'s concrete subclasses.
031 *
032 * @author Rossen Stoyanchev
033 * @author Sebastien Deleuze
034 * @since 4.1
035 */
036public abstract class AbstractMappingJacksonResponseBodyAdvice implements ResponseBodyAdvice<Object> {
037
038        @Override
039        public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
040                return AbstractJackson2HttpMessageConverter.class.isAssignableFrom(converterType);
041        }
042
043        @Override
044        public final Object beforeBodyWrite(Object body, MethodParameter returnType,
045                        MediaType contentType, Class<? extends HttpMessageConverter<?>> converterType,
046                        ServerHttpRequest request, ServerHttpResponse response) {
047
048                MappingJacksonValue container = getOrCreateContainer(body);
049                beforeBodyWriteInternal(container, contentType, returnType, request, response);
050                return container;
051        }
052
053        /**
054         * Wrap the body in a {@link MappingJacksonValue} value container (for providing
055         * additional serialization instructions) or simply cast it if already wrapped.
056         */
057        protected MappingJacksonValue getOrCreateContainer(Object body) {
058                return (body instanceof MappingJacksonValue ? (MappingJacksonValue) body : new MappingJacksonValue(body));
059        }
060
061        /**
062         * Invoked only if the converter type is {@code MappingJackson2HttpMessageConverter}.
063         */
064        protected abstract void beforeBodyWriteInternal(MappingJacksonValue bodyContainer, MediaType contentType,
065                        MethodParameter returnType, ServerHttpRequest request, ServerHttpResponse response);
066
067}