org.springframework.http.codec.protobuf.ProtobufHttpMessageWriter Maven / Gradle / Ivy
/*
* 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
*
* https://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.http.codec.protobuf;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentMap;
import com.google.protobuf.Descriptors;
import com.google.protobuf.Message;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import org.springframework.core.ResolvableType;
import org.springframework.core.codec.DecodingException;
import org.springframework.core.codec.Encoder;
import org.springframework.http.MediaType;
import org.springframework.http.ReactiveHttpOutputMessage;
import org.springframework.http.codec.EncoderHttpMessageWriter;
import org.springframework.http.codec.HttpMessageEncoder;
import org.springframework.lang.Nullable;
import org.springframework.util.ConcurrentReferenceHashMap;
/**
* {@code HttpMessageWriter} that can write a protobuf {@link Message} and adds
* {@code X-Protobuf-Schema}, {@code X-Protobuf-Message} headers and a
* {@code delimited=true} parameter is added to the content type if a flux is serialized.
*
* For {@code HttpMessageReader}, just use
* {@code new DecoderHttpMessageReader(new ProtobufDecoder())}.
*
* @author Sebastien Deleuze
* @since 5.1
* @see ProtobufEncoder
*/
public class ProtobufHttpMessageWriter extends EncoderHttpMessageWriter {
private static final String X_PROTOBUF_SCHEMA_HEADER = "X-Protobuf-Schema";
private static final String X_PROTOBUF_MESSAGE_HEADER = "X-Protobuf-Message";
private static final ConcurrentMap, Method> methodCache = new ConcurrentReferenceHashMap<>();
/**
* Create a new {@code ProtobufHttpMessageWriter} with a default {@link ProtobufEncoder}.
*/
public ProtobufHttpMessageWriter() {
super(new ProtobufEncoder());
}
/**
* Create a new {@code ProtobufHttpMessageWriter} with the given encoder.
* @param encoder the Protobuf message encoder to use
*/
public ProtobufHttpMessageWriter(Encoder encoder) {
super(encoder);
}
@SuppressWarnings("unchecked")
@Override
public Mono write(Publisher inputStream, ResolvableType elementType,
@Nullable MediaType mediaType, ReactiveHttpOutputMessage message, Map hints) {
try {
Message.Builder builder = getMessageBuilder(elementType.toClass());
Descriptors.Descriptor descriptor = builder.getDescriptorForType();
message.getHeaders().add(X_PROTOBUF_SCHEMA_HEADER, descriptor.getFile().getName());
message.getHeaders().add(X_PROTOBUF_MESSAGE_HEADER, descriptor.getFullName());
if (inputStream instanceof Flux) {
if (mediaType == null) {
message.getHeaders().setContentType(((HttpMessageEncoder)getEncoder()).getStreamingMediaTypes().get(0));
}
else if (!ProtobufEncoder.DELIMITED_VALUE.equals(mediaType.getParameters().get(ProtobufEncoder.DELIMITED_KEY))) {
Map parameters = new HashMap<>(mediaType.getParameters());
parameters.put(ProtobufEncoder.DELIMITED_KEY, ProtobufEncoder.DELIMITED_VALUE);
message.getHeaders().setContentType(new MediaType(mediaType.getType(), mediaType.getSubtype(), parameters));
}
}
return super.write(inputStream, elementType, mediaType, message, hints);
}
catch (Exception ex) {
return Mono.error(new DecodingException("Could not read Protobuf message: " + ex.getMessage(), ex));
}
}
/**
* Create a new {@code Message.Builder} instance for the given class.
* This method uses a ConcurrentHashMap for caching method lookups.
*/
private static Message.Builder getMessageBuilder(Class clazz) throws Exception {
Method method = methodCache.get(clazz);
if (method == null) {
method = clazz.getMethod("newBuilder");
methodCache.put(clazz, method);
}
return (Message.Builder) method.invoke(clazz);
}
}