/*
* Copyright 2002-2014 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.http.converter.protobuf;
import com.google.protobuf.ExtensionRegistry;
import com.google.protobuf.Message;
import com.google.protobuf.TextFormat;
import com.googlecode.protobuf.format.HtmlFormat;
import com.googlecode.protobuf.format.JsonFormat;
import com.googlecode.protobuf.format.XmlFormat;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.util.FileCopyUtils;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.lang.reflect.Method;
import java.nio.charset.Charset;
import java.util.concurrent.ConcurrentHashMap;
/**
* An {@code HttpMessageConverter} that can read and write Protobuf
* {@link com.google.protobuf.Message} using
* <a href="https://developers.google.com/protocol-buffers/">Google Protocol buffers</a>.
*
* <p>By default it supports {@code "application/json"}, {@code "application/xml"},
* {@code "text/plain"} and {@code "application/x-protobuf"} while writing also
* supports {@code "text/html"}
*
* <p>To generate Message Java classes you need to install the protoc binary.
*
* <p>Tested against Protobuf version 2.5.0.
*
* @author Alex Antonov
* @author Brian Clozel
* @since 4.1
*/
public class ProtobufHttpMessageConverter extends AbstractHttpMessageConverter<Message> {
public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
public static final MediaType PROTOBUF = new MediaType("application", "x-protobuf", DEFAULT_CHARSET);
public static final String X_PROTOBUF_SCHEMA_HEADER = "X-Protobuf-Schema";
public static final String X_PROTOBUF_MESSAGE_HEADER = "X-Protobuf-Message";
private static final ConcurrentHashMap<Class<?>, Method> methodCache = new ConcurrentHashMap<Class<?>, Method>();
private ExtensionRegistry extensionRegistry = ExtensionRegistry.newInstance();
/**
* Construct a new instance.
*/
public ProtobufHttpMessageConverter() {
this(null);
}
/**
* Construct a new instance with an {@link ExtensionRegistryInitializer}
* that allows the registration of message extensions.
*/
public ProtobufHttpMessageConverter(ExtensionRegistryInitializer registryInitializer) {
super(PROTOBUF, MediaType.TEXT_PLAIN, MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON);
if (this.extensionRegistry != null) {
registryInitializer.initializeExtensionRegistry(this.extensionRegistry);
}
}
@Override
protected boolean supports(Class<?> clazz) {
return Message.class.isAssignableFrom(clazz);
}
@Override
protected Message readInternal(Class<? extends Message> clazz, HttpInputMessage inputMessage)
throws IOException, HttpMessageNotReadableException {
MediaType contentType = inputMessage.getHeaders().getContentType();
contentType = (contentType != null ? contentType : PROTOBUF);
Charset charset = getCharset(inputMessage.getHeaders());
InputStreamReader reader = new InputStreamReader(inputMessage.getBody(), charset);
try {
Message.Builder builder = getMessageBuilder(clazz);
if (MediaType.APPLICATION_JSON.isCompatibleWith(contentType)) {
JsonFormat.merge(reader, this.extensionRegistry, builder);
}
else if (MediaType.TEXT_PLAIN.isCompatibleWith(contentType)) {
TextFormat.merge(reader, this.extensionRegistry, builder);
}
else if (MediaType.APPLICATION_XML.isCompatibleWith(contentType)) {
XmlFormat.merge(reader, this.extensionRegistry, builder);
}
else {
builder.mergeFrom(inputMessage.getBody(), this.extensionRegistry);
}
return builder.build();
}
catch (Exception e) {
throw new HttpMessageNotReadableException("Could not read Protobuf message: " + e.getMessage(), e);
}
}
private Charset getCharset(HttpHeaders headers) {
if (headers == null || headers.getContentType() == null || headers.getContentType().getCharSet() == null) {
return DEFAULT_CHARSET;
}
return headers.getContentType().getCharSet();
}
/**
* Create a new {@code Message.Builder} instance for the given class.
* <p>This method uses a ConcurrentHashMap for caching method lookups.
*/
private Message.Builder getMessageBuilder(Class<? extends Message> 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);
}
/**
* This method overrides the parent implementation, since this HttpMessageConverter
* can also produce {@code MediaType.HTML "text/html"} ContentType.
*/
@Override
protected boolean canWrite(MediaType mediaType) {
return super.canWrite(mediaType) || MediaType.TEXT_HTML.isCompatibleWith(mediaType);
}
@Override
protected void writeInternal(Message message, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
MediaType contentType = outputMessage.getHeaders().getContentType();
Charset charset = getCharset(contentType);
OutputStreamWriter writer = new OutputStreamWriter(outputMessage.getBody(), charset);
if (MediaType.TEXT_HTML.isCompatibleWith(contentType)) {
HtmlFormat.print(message, writer);
}
else if (MediaType.APPLICATION_JSON.isCompatibleWith(contentType)) {
JsonFormat.print(message, writer);
}
else if (MediaType.TEXT_PLAIN.isCompatibleWith(contentType)) {
TextFormat.print(message, writer);
}
else if (MediaType.APPLICATION_XML.isCompatibleWith(contentType)) {
XmlFormat.print(message, writer);
}
else if (PROTOBUF.isCompatibleWith(contentType)) {
//setProtoHeader(outputMessage, message);
FileCopyUtils.copy(message.toByteArray(), outputMessage.getBody());
}
}
private Charset getCharset(MediaType contentType) {
return contentType.getCharSet() != null ? contentType.getCharSet() : DEFAULT_CHARSET;
}
/**
* Set the "X-Protobuf-*" HTTP headers when responding with a message of
* content type "application/x-protobuf"
*/
private void setProtoHeader(HttpOutputMessage response, Message message) {
response.getHeaders().set(X_PROTOBUF_SCHEMA_HEADER, message.getDescriptorForType().getFile().getName());
response.getHeaders().set(X_PROTOBUF_MESSAGE_HEADER, message.getDescriptorForType().getFullName());
}
@Override
protected MediaType getDefaultContentType(Message message) {
return PROTOBUF;
}
}