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.reactivestreams.Publisher; 023import reactor.core.publisher.Mono; 024 025import org.springframework.core.MethodParameter; 026import org.springframework.core.ResolvableType; 027import org.springframework.http.MediaType; 028import org.springframework.http.ReactiveHttpOutputMessage; 029import org.springframework.http.server.reactive.ServerHttpRequest; 030import org.springframework.http.server.reactive.ServerHttpResponse; 031import org.springframework.lang.Nullable; 032 033/** 034 * Strategy for encoding a stream of objects of type {@code <T>} and writing 035 * the encoded stream of bytes to an {@link ReactiveHttpOutputMessage}. 036 * 037 * @author Rossen Stoyanchev 038 * @author Arjen Poutsma 039 * @author Sebastien Deleuze 040 * @since 5.0 041 * @param <T> the type of objects in the input stream 042 */ 043public interface HttpMessageWriter<T> { 044 045 /** 046 * Return the {@link MediaType}'s that this writer supports. 047 */ 048 List<MediaType> getWritableMediaTypes(); 049 050 /** 051 * Whether the given object type is supported by this writer. 052 * @param elementType the type of object to check 053 * @param mediaType the media type for the write (possibly {@code null}) 054 * @return {@code true} if writable, {@code false} otherwise 055 */ 056 boolean canWrite(ResolvableType elementType, @Nullable MediaType mediaType); 057 058 /** 059 * Write an given stream of object to the output message. 060 * @param inputStream the objects to write 061 * @param elementType the type of objects in the stream which must have been 062 * previously checked via {@link #canWrite(ResolvableType, MediaType)} 063 * @param mediaType the content type for the write (possibly {@code null} to 064 * indicate that the default content type of the writer must be used) 065 * @param message the message to write to 066 * @param hints additional information about how to encode and write 067 * @return indicates completion or error 068 */ 069 Mono<Void> write(Publisher<? extends T> inputStream, ResolvableType elementType, 070 @Nullable MediaType mediaType, ReactiveHttpOutputMessage message, Map<String, Object> hints); 071 072 /** 073 * Server-side only alternative to 074 * {@link #write(Publisher, ResolvableType, MediaType, ReactiveHttpOutputMessage, Map)} 075 * with additional context available. 076 * @param actualType the actual return type of the method that returned the 077 * value; for annotated controllers, the {@link MethodParameter} can be 078 * accessed via {@link ResolvableType#getSource()}. 079 * @param elementType the type of Objects in the input stream 080 * @param mediaType the content type to use (possibly {@code null} indicating 081 * the default content type of the writer should be used) 082 * @param request the current request 083 * @param response the current response 084 * @return a {@link Mono} that indicates completion of writing or error 085 */ 086 default Mono<Void> write(Publisher<? extends T> inputStream, ResolvableType actualType, 087 ResolvableType elementType, @Nullable MediaType mediaType, ServerHttpRequest request, 088 ServerHttpResponse response, Map<String, Object> hints) { 089 090 return write(inputStream, elementType, mediaType, response, hints); 091 } 092 093}