/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
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package org.springframework.http.codec;

import java.util.List;
import java.util.Map;

import org.reactivestreams.Publisher;
import reactor.core.publisher.Mono;

import org.springframework.core.MethodParameter;
import org.springframework.core.ResolvableType;
import org.springframework.http.MediaType;
import org.springframework.http.ReactiveHttpOutputMessage;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.lang.Nullable;

Strategy for encoding a stream of objects of type <T> and writing the encoded stream of bytes to an ReactiveHttpOutputMessage.
Author:Rossen Stoyanchev, Arjen Poutsma, Sebastien Deleuze
Type parameters:
  • <T> – the type of objects in the input stream
Since:5.0
/** * Strategy for encoding a stream of objects of type {@code <T>} and writing * the encoded stream of bytes to an {@link ReactiveHttpOutputMessage}. * * @author Rossen Stoyanchev * @author Arjen Poutsma * @author Sebastien Deleuze * @since 5.0 * @param <T> the type of objects in the input stream */
public interface HttpMessageWriter<T> {
Return the MediaType's that this writer supports.
/** * Return the {@link MediaType}'s that this writer supports. */
List<MediaType> getWritableMediaTypes();
Whether the given object type is supported by this writer.
Params:
  • elementType – the type of object to check
  • mediaType – the media type for the write, possibly null
Returns:true if writable, false otherwise
/** * Whether the given object type is supported by this writer. * @param elementType the type of object to check * @param mediaType the media type for the write, possibly {@code null} * @return {@code true} if writable, {@code false} otherwise */
boolean canWrite(ResolvableType elementType, @Nullable MediaType mediaType);
Write an given stream of object to the output message.
Params:
  • inputStream – the objects to write
  • elementType – the type of objects in the stream which must have been previously checked via canWrite(ResolvableType, MediaType)
  • mediaType – the content type for the write, possibly null to indicate that the default content type of the writer must be used.
  • message – the message to write to
  • hints – additional information about how to encode and write
Returns:indicates completion or error
/** * Write an given stream of object to the output message. * @param inputStream the objects to write * @param elementType the type of objects in the stream which must have been * previously checked via {@link #canWrite(ResolvableType, MediaType)} * @param mediaType the content type for the write, possibly {@code null} to * indicate that the default content type of the writer must be used. * @param message the message to write to * @param hints additional information about how to encode and write * @return indicates completion or error */
Mono<Void> write(Publisher<? extends T> inputStream, ResolvableType elementType, @Nullable MediaType mediaType, ReactiveHttpOutputMessage message, Map<String, Object> hints);
Server-side only alternative to write(Publisher, ResolvableType, MediaType, ReactiveHttpOutputMessage, Map) with additional context available.
Params:
  • actualType – the actual return type of the method that returned the value; for annotated controllers, the MethodParameter can be accessed via ResolvableType.getSource().
  • elementType – the type of Objects in the input stream
  • mediaType – the content type to use, possibly null indicating the default content type of the writer should be used.
  • request – the current request
  • response – the current response
Returns:a Mono that indicates completion of writing or error
/** * Server-side only alternative to * {@link #write(Publisher, ResolvableType, MediaType, ReactiveHttpOutputMessage, Map)} * with additional context available. * @param actualType the actual return type of the method that returned the * value; for annotated controllers, the {@link MethodParameter} can be * accessed via {@link ResolvableType#getSource()}. * @param elementType the type of Objects in the input stream * @param mediaType the content type to use, possibly {@code null} indicating * the default content type of the writer should be used. * @param request the current request * @param response the current response * @return a {@link Mono} that indicates completion of writing or error */
default Mono<Void> write(Publisher<? extends T> inputStream, ResolvableType actualType, ResolvableType elementType, @Nullable MediaType mediaType, ServerHttpRequest request, ServerHttpResponse response, Map<String, Object> hints) { return write(inputStream, elementType, mediaType, response, hints); } }