org.springframework.http.converter.protobuf.ProtobufHttpMessageConverter Maven / Gradle / Ivy
/*
* Copyright 2002-2016 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 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;
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.ProtobufFormatter;
import com.googlecode.protobuf.format.XmlFormat;
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;
/**
* An {@code HttpMessageConverter} that reads and writes {@link com.google.protobuf.Message}s
* using Google Protocol Buffers.
*
* By default, it supports {@code "application/x-protobuf"}, {@code "text/plain"},
* {@code "application/json"}, {@code "application/xml"}, while also writing {@code "text/html"}.
*
*
To generate {@code Message} Java classes, you need to install the {@code protoc} binary.
*
*
Requires Protobuf 2.6 and Protobuf Java Format 1.4, as of Spring 4.3.
*
* @author Alex Antonov
* @author Brian Clozel
* @author Juergen Hoeller
* @since 4.1
*/
public class ProtobufHttpMessageConverter extends AbstractHttpMessageConverter {
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 ProtobufFormatter JSON_FORMAT = new JsonFormat();
private static final ProtobufFormatter XML_FORMAT = new XmlFormat();
private static final ProtobufFormatter HTML_FORMAT = new HtmlFormat();
private static final ConcurrentHashMap, Method> methodCache = new ConcurrentHashMap, Method>();
private final 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_JSON, MediaType.APPLICATION_XML);
if (registryInitializer != null) {
registryInitializer.initializeExtensionRegistry(this.extensionRegistry);
}
}
@Override
protected boolean supports(Class clazz) {
return Message.class.isAssignableFrom(clazz);
}
@Override
protected MediaType getDefaultContentType(Message message) {
return PROTOBUF;
}
@Override
protected Message readInternal(Class clazz, HttpInputMessage inputMessage)
throws IOException, HttpMessageNotReadableException {
MediaType contentType = inputMessage.getHeaders().getContentType();
if (contentType == null) {
contentType = PROTOBUF;
}
Charset charset = contentType.getCharset();
if (charset == null) {
charset = DEFAULT_CHARSET;
}
try {
Message.Builder builder = getMessageBuilder(clazz);
if (MediaType.TEXT_PLAIN.isCompatibleWith(contentType)) {
InputStreamReader reader = new InputStreamReader(inputMessage.getBody(), charset);
TextFormat.merge(reader, this.extensionRegistry, builder);
}
else if (MediaType.APPLICATION_JSON.isCompatibleWith(contentType)) {
JSON_FORMAT.merge(inputMessage.getBody(), charset, this.extensionRegistry, builder);
}
else if (MediaType.APPLICATION_XML.isCompatibleWith(contentType)) {
XML_FORMAT.merge(inputMessage.getBody(), charset, this.extensionRegistry, builder);
}
else {
builder.mergeFrom(inputMessage.getBody(), this.extensionRegistry);
}
return builder.build();
}
catch (Exception ex) {
throw new HttpMessageNotReadableException("Could not read Protobuf message: " + ex.getMessage(), ex);
}
}
/**
* 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();
if (contentType == null) {
contentType = getDefaultContentType(message);
}
Charset charset = contentType.getCharset();
if (charset == null) {
charset = DEFAULT_CHARSET;
}
if (MediaType.TEXT_PLAIN.isCompatibleWith(contentType)) {
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputMessage.getBody(), charset);
TextFormat.print(message, outputStreamWriter);
outputStreamWriter.flush();
}
else if (MediaType.APPLICATION_JSON.isCompatibleWith(contentType)) {
JSON_FORMAT.print(message, outputMessage.getBody(), charset);
}
else if (MediaType.APPLICATION_XML.isCompatibleWith(contentType)) {
XML_FORMAT.print(message, outputMessage.getBody(), charset);
}
else if (MediaType.TEXT_HTML.isCompatibleWith(contentType)) {
HTML_FORMAT.print(message, outputMessage.getBody(), charset);
}
else if (PROTOBUF.isCompatibleWith(contentType)) {
setProtoHeader(outputMessage, message);
FileCopyUtils.copy(message.toByteArray(), outputMessage.getBody());
}
}
/**
* Set the "X-Protobuf-*" HTTP headers when responding with a message of
* content type "application/x-protobuf"
* Note: outputMessage.getBody() should not have been called
* before because it writes HTTP headers (making them read only).
*/
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());
}
/**
* 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);
}
}