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; 026import org.springframework.lang.Nullable; 027 028/** 029 * A convenient base class for {@code ResponseBodyAdvice} implementations 030 * that customize the response before JSON serialization with 031 * {@link AbstractJackson2HttpMessageConverter}'s concrete subclasses. 032 * 033 * @author Rossen Stoyanchev 034 * @author Sebastien Deleuze 035 * @since 4.1 036 */ 037public abstract class AbstractMappingJacksonResponseBodyAdvice implements ResponseBodyAdvice<Object> { 038 039 @Override 040 public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) { 041 return AbstractJackson2HttpMessageConverter.class.isAssignableFrom(converterType); 042 } 043 044 @Override 045 @Nullable 046 public final Object beforeBodyWrite(@Nullable Object body, MethodParameter returnType, 047 MediaType contentType, Class<? extends HttpMessageConverter<?>> converterType, 048 ServerHttpRequest request, ServerHttpResponse response) { 049 050 if (body == null) { 051 return null; 052 } 053 MappingJacksonValue container = getOrCreateContainer(body); 054 beforeBodyWriteInternal(container, contentType, returnType, request, response); 055 return container; 056 } 057 058 /** 059 * Wrap the body in a {@link MappingJacksonValue} value container (for providing 060 * additional serialization instructions) or simply cast it if already wrapped. 061 */ 062 protected MappingJacksonValue getOrCreateContainer(Object body) { 063 return (body instanceof MappingJacksonValue ? (MappingJacksonValue) body : new MappingJacksonValue(body)); 064 } 065 066 /** 067 * Invoked only if the converter type is {@code MappingJackson2HttpMessageConverter}. 068 */ 069 protected abstract void beforeBodyWriteInternal(MappingJacksonValue bodyContainer, MediaType contentType, 070 MethodParameter returnType, ServerHttpRequest request, ServerHttpResponse response); 071 072}