/*
* Copyright 2002-2017 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
* limitations under the License.
*/
package org.springframework.web.reactive.function;
import java.util.List;
import java.util.Optional;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Mono;
import org.springframework.core.ResolvableType;
import org.springframework.core.io.Resource;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.MediaType;
import org.springframework.http.ReactiveHttpOutputMessage;
import org.springframework.http.client.reactive.ClientHttpRequest;
import org.springframework.http.codec.HttpMessageWriter;
import org.springframework.http.codec.ServerSentEvent;
import org.springframework.http.codec.multipart.Part;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.util.Assert;
import org.springframework.util.MultiValueMap;
/**
* Implementations of {@link BodyInserter} that write various bodies, such a reactive streams,
* server-sent events, resources, etc.
*
* @author Arjen Poutsma
* @since 5.0
*/
public abstract class BodyInserters {
private static final ResolvableType RESOURCE_TYPE =
ResolvableType.forClass(Resource.class);
private static final ResolvableType SERVER_SIDE_EVENT_TYPE =
ResolvableType.forClass(ServerSentEvent.class);
private static final ResolvableType FORM_TYPE =
ResolvableType.forClassWithGenerics(MultiValueMap.class, String.class, String.class);
private static final ResolvableType MULTIPART_VALUE_TYPE = ResolvableType.forClassWithGenerics(
MultiValueMap.class, String.class, Part.class);
private static final BodyInserter<Void, ReactiveHttpOutputMessage> EMPTY =
(response, context) -> response.setComplete();
/**
* Return an empty {@code BodyInserter} that writes nothing.
* @return an empty {@code BodyInserter}
*/
@SuppressWarnings("unchecked")
public static <T> BodyInserter<T, ReactiveHttpOutputMessage> empty() {
return (BodyInserter<T, ReactiveHttpOutputMessage>)EMPTY;
}
/**
* Return a {@code BodyInserter} that writes the given single object.
* @param body the body of the response
* @return a {@code BodyInserter} that writes a single object
*/
public static <T> BodyInserter<T, ReactiveHttpOutputMessage> fromObject(T body) {
Assert.notNull(body, "'body' must not be null");
return bodyInserterFor(Mono.just(body), ResolvableType.forInstance(body));
}
/**
* Return a {@code BodyInserter} that writes the given {@link Publisher}.
* @param publisher the publisher to stream to the response body
* @param elementClass the class of elements contained in the publisher
* @param <T> the type of the elements contained in the publisher
* @param <P> the type of the {@code Publisher}
* @return a {@code BodyInserter} that writes a {@code Publisher}
*/
public static <T, P extends Publisher<T>> BodyInserter<P, ReactiveHttpOutputMessage> fromPublisher(
P publisher, Class<T> elementClass) {
Assert.notNull(publisher, "'publisher' must not be null");
Assert.notNull(elementClass, "'elementClass' must not be null");
return bodyInserterFor(publisher, ResolvableType.forClass(elementClass));
}
/**
* Return a {@code BodyInserter} that writes the given {@link Publisher}.
* @param publisher the publisher to stream to the response body
* @param elementType the type of elements contained in the publisher
* @param <T> the type of the elements contained in the publisher
* @param <P> the type of the {@code Publisher}
* @return a {@code BodyInserter} that writes a {@code Publisher}
*/
public static <T, P extends Publisher<T>> BodyInserter<P, ReactiveHttpOutputMessage> fromPublisher(
P publisher, ResolvableType elementType) {
Assert.notNull(publisher, "'publisher' must not be null");
Assert.notNull(elementType, "'elementType' must not be null");
return bodyInserterFor(publisher, elementType);
}
/**
* Return a {@code BodyInserter} that writes the given {@code Resource}.
* <p>If the resource can be resolved to a {@linkplain Resource#getFile() file}, it will
* be copied using <a href="https://en.wikipedia.org/wiki/Zero-copy">zero-copy</a>.
* @param resource the resource to write to the output message
* @param <T> the type of the {@code Resource}
* @return a {@code BodyInserter} that writes a {@code Publisher}
*/
public static <T extends Resource> BodyInserter<T, ReactiveHttpOutputMessage> fromResource(T resource) {
Assert.notNull(resource, "'resource' must not be null");
return (outputMessage, context) -> {
Mono<T> inputStream = Mono.just(resource);
HttpMessageWriter<Resource> messageWriter = resourceHttpMessageWriter(context);
Optional<ServerHttpRequest> serverRequest = context.serverRequest();
if (serverRequest.isPresent() && outputMessage instanceof ServerHttpResponse) {
return messageWriter.write(inputStream, RESOURCE_TYPE, RESOURCE_TYPE, null,
serverRequest.get(), (ServerHttpResponse) outputMessage, context.hints());
}
else {
return messageWriter.write(inputStream, RESOURCE_TYPE, null,
outputMessage, context.hints());
}
};
}
private static HttpMessageWriter<Resource> resourceHttpMessageWriter(BodyInserter.Context context) {
return context.messageWriters().get()
.filter(messageWriter -> messageWriter.canWrite(RESOURCE_TYPE, null))
.findFirst()
.map(BodyInserters::<Resource>cast)
.orElseThrow(() -> new IllegalStateException(
"Could not find HttpMessageWriter that supports Resource objects"));
}
/**
* Return a {@code BodyInserter} that writes the given {@code ServerSentEvent} publisher.
* @param eventsPublisher the {@code ServerSentEvent} publisher to write to the response body
* @param <T> the type of the elements contained in the {@link ServerSentEvent}
* @return a {@code BodyInserter} that writes a {@code ServerSentEvent} publisher
* @see <a href="https://www.w3.org/TR/eventsource/">Server-Sent Events W3C recommendation</a>
*/
// Note that the returned BodyInserter is parameterized to ServerHttpResponse, not
// ReactiveHttpOutputMessage like other methods, since sending SSEs only typically happens on
// the server-side
public static <T, S extends Publisher<ServerSentEvent<T>>> BodyInserter<S, ServerHttpResponse> fromServerSentEvents(
S eventsPublisher) {
Assert.notNull(eventsPublisher, "'eventsPublisher' must not be null");
return (serverResponse, context) -> {
HttpMessageWriter<ServerSentEvent<T>> messageWriter =
findMessageWriter(context, SERVER_SIDE_EVENT_TYPE, MediaType.TEXT_EVENT_STREAM);
return context.serverRequest()
.map(serverRequest -> messageWriter.write(eventsPublisher, SERVER_SIDE_EVENT_TYPE,
SERVER_SIDE_EVENT_TYPE, MediaType.TEXT_EVENT_STREAM, serverRequest,
serverResponse, context.hints()))
.orElseGet(() -> messageWriter.write(eventsPublisher, SERVER_SIDE_EVENT_TYPE,
MediaType.TEXT_EVENT_STREAM, serverResponse, context.hints()));
};
}
/**
* Return a {@code BodyInserter} that writes the given {@code Publisher} publisher as
* Server-Sent Events.
* @param eventsPublisher the publisher to write to the response body as Server-Sent Events
* @param eventClass the class of event contained in the publisher
* @param <T> the type of the elements contained in the publisher
* @return a {@code BodyInserter} that writes the given {@code Publisher} publisher as
* Server-Sent Events
* @see <a href="https://www.w3.org/TR/eventsource/">Server-Sent Events W3C recommendation</a>
*/
// Note that the returned BodyInserter is parameterized to ServerHttpResponse, not
// ReactiveHttpOutputMessage like other methods, since sending SSEs only typically happens on
// the server-side
public static <T, S extends Publisher<T>> BodyInserter<S, ServerHttpResponse> fromServerSentEvents(S eventsPublisher,
Class<T> eventClass) {
Assert.notNull(eventsPublisher, "'eventsPublisher' must not be null");
Assert.notNull(eventClass, "'eventClass' must not be null");
return fromServerSentEvents(eventsPublisher, ResolvableType.forClass(eventClass));
}
/**
* Return a {@code BodyInserter} that writes the given {@code Publisher} publisher as
* Server-Sent Events.
* @param eventsPublisher the publisher to write to the response body as Server-Sent Events
* @param eventType the type of event contained in the publisher
* @param <T> the type of the elements contained in the publisher
* @return a {@code BodyInserter} that writes the given {@code Publisher} publisher as
* Server-Sent Events
* @see <a href="https://www.w3.org/TR/eventsource/">Server-Sent Events W3C recommendation</a>
*/
// Note that the returned BodyInserter is parameterized to ServerHttpResponse, not
// ReactiveHttpOutputMessage like other methods, since sending SSEs only typically happens on
// the server-side
public static <T, S extends Publisher<T>> BodyInserter<S, ServerHttpResponse> fromServerSentEvents(S eventsPublisher,
ResolvableType eventType) {
Assert.notNull(eventsPublisher, "'eventsPublisher' must not be null");
Assert.notNull(eventType, "'eventType' must not be null");
return (serverResponse, context) -> {
HttpMessageWriter<T> messageWriter =
findMessageWriter(context, SERVER_SIDE_EVENT_TYPE, MediaType.TEXT_EVENT_STREAM);
return context.serverRequest()
.map(serverRequest -> messageWriter.write(eventsPublisher, eventType,
eventType, MediaType.TEXT_EVENT_STREAM, serverRequest,
serverResponse, context.hints()))
.orElseGet(() -> messageWriter.write(eventsPublisher, eventType,
MediaType.TEXT_EVENT_STREAM, serverResponse, context.hints()));
};
}
/**
* Return a {@code BodyInserter} that writes the given {@code MultiValueMap} as URL-encoded
* form data.
* @param formData the form data to write to the output message
* @return a {@code BodyInserter} that writes form data
*/
// Note that the returned BodyInserter is parameterized to ClientHttpRequest, not
// ReactiveHttpOutputMessage like other methods, since sending form data only typically happens
// on the server-side
public static BodyInserter<MultiValueMap<String, String>, ClientHttpRequest> fromFormData(
MultiValueMap<String, String> formData) {
Assert.notNull(formData, "'formData' must not be null");
return (outputMessage, context) -> {
HttpMessageWriter<MultiValueMap<String, String>> messageWriter =
findMessageWriter(context, FORM_TYPE, MediaType.APPLICATION_FORM_URLENCODED);
return messageWriter.write(Mono.just(formData), FORM_TYPE,
MediaType.APPLICATION_FORM_URLENCODED, outputMessage, context.hints());
};
}
/**
* Return a {@code BodyInserter} that writes the given {@code MultiValueMap} as Multipart
* data.
* @param multipartData the form data to write to the output message
* @return a {@code BodyInserter} that writes form data
*/
// Note that the returned BodyInserter is parameterized to ClientHttpRequest, not
// ReactiveHttpOutputMessage like other methods, since sending form data only typically happens
// on the server-side
public static BodyInserter<MultiValueMap<String, ?>, ClientHttpRequest> fromMultipartData(
MultiValueMap<String, ?> multipartData) {
Assert.notNull(multipartData, "'multipartData' must not be null");
return (outputMessage, context) -> {
HttpMessageWriter<MultiValueMap<String, ?>> messageWriter =
findMessageWriter(context, MULTIPART_VALUE_TYPE, MediaType.MULTIPART_FORM_DATA);
return messageWriter.write(Mono.just(multipartData), FORM_TYPE,
MediaType.MULTIPART_FORM_DATA, outputMessage, context.hints());
};
}
/**
* Return a {@code BodyInserter} that writes the given {@code Publisher<DataBuffer>} to the body.
* @param publisher the data buffer publisher to write
* @param <T> the type of the publisher
* @return a {@code BodyInserter} that writes directly to the body
* @see ReactiveHttpOutputMessage#writeWith(Publisher)
*/
public static <T extends Publisher<DataBuffer>> BodyInserter<T, ReactiveHttpOutputMessage> fromDataBuffers(
T publisher) {
Assert.notNull(publisher, "'publisher' must not be null");
return (outputMessage, context) -> outputMessage.writeWith(publisher);
}
private static <T, P extends Publisher<?>, M extends ReactiveHttpOutputMessage> BodyInserter<T, M> bodyInserterFor(
P body, ResolvableType bodyType) {
return (outputMessage, context) -> {
MediaType contentType = outputMessage.getHeaders().getContentType();
Supplier<Stream<HttpMessageWriter<?>>> messageWriters = context.messageWriters();
return messageWriters.get()
.filter(messageWriter -> messageWriter.canWrite(bodyType, contentType))
.findFirst()
.map(BodyInserters::cast)
.map(messageWriter -> {
Optional<ServerHttpRequest> serverRequest = context.serverRequest();
if (serverRequest.isPresent() && outputMessage instanceof ServerHttpResponse) {
return messageWriter.write(body, bodyType, bodyType, contentType,
serverRequest.get(), (ServerHttpResponse) outputMessage,
context.hints());
} else {
return messageWriter.write(body, bodyType, contentType, outputMessage,
context.hints());
}
})
.orElseGet(() -> {
List<MediaType> supportedMediaTypes = messageWriters.get()
.flatMap(reader -> reader.getWritableMediaTypes().stream())
.collect(Collectors.toList());
UnsupportedMediaTypeException error =
new UnsupportedMediaTypeException(contentType, supportedMediaTypes);
return Mono.error(error);
});
};
}
private static <T> HttpMessageWriter<T> findMessageWriter(
BodyInserter.Context context, ResolvableType type, MediaType mediaType) {
return context.messageWriters().get()
.filter(messageWriter -> messageWriter.canWrite(type, mediaType))
.findFirst()
.map(BodyInserters::<T>cast)
.orElseThrow(() -> new IllegalStateException(
"Could not find HttpMessageWriter that supports " + mediaType));
}
@SuppressWarnings("unchecked")
private static <T> HttpMessageWriter<T> cast(HttpMessageWriter<?> messageWriter) {
return (HttpMessageWriter<T>) messageWriter;
}
}