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Add Google Protobuf support with a MessageConverter

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This change adds a new HttpMessageConverter supporting
Google protocol buffers (aka Protobuf).
This message converter supports the following media types:
* application/json
* application/xml
* text/plain
* text/html (output only)
* and by default application/x-protobuf

Note, in order to generate Proto Message classes, the protoc binary
must be available on your system.

Issue: SPR-5807/SPR-6259
This commit is contained in:
Brian Clozel
2014-07-17 18:24:03 +02:00
committed by Rossen Stoyanchev
parent 105ea196e4
commit b56703eadc
10 changed files with 1540 additions and 0 deletions
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40
spring-web/src/main/java/org/springframework/http/converter/protobuf/ExtensionRegistryInitializer.java Normal file
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/*
* 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;
/**
* Google Protocol Messages can contain message extensions that can be parsed if
* the appropriate configuration has been registered in the {@code ExtensionRegistry}.
*
* This interface provides a facility to populate the {@code ExtensionRegistry}.
*
* @author Alex Antonov
* @since 4.1
* @see <a href="https://developers.google.com/protocol-buffers/docs/reference/java/com/google/protobuf/ExtensionRegistry">
* com.google.protobuf.ExtensionRegistry</a>
*/
public interface ExtensionRegistryInitializer {
/**
* Initializes the {@code ExtensionRegistry} with Protocol Message extensions
* @param registry the registry to populate
*/
void initializeExtensionRegistry(ExtensionRegistry registry);
}

204
spring-web/src/main/java/org/springframework/http/converter/protobuf/ProtobufHttpMessageConverter.java Normal file
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/*
* 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 java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
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.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.Assert;
import org.springframework.util.FileCopyUtils;
/**
* Implementation of {@link org.springframework.http.converter.HttpMessageConverter}
* that can read and write Protobuf {@code Message}s using the
* <a href="https://developers.google.com/protocol-buffers/">Google Protocol buffers</a> library.
*
* <p>By default, it supports {@code application/json}, {@code application/xml}, {@code text/plain}
* and {@code application/x-protobuf}. {@code text/html} is only supported when writing messages.
*
* <p>In order to generate Message Java classes, you should install the protoc binary on your system.
* <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> newBuilderMethodCache =
new ConcurrentHashMap<Class<?>, Method>();
private ExtensionRegistry extensionRegistry = ExtensionRegistry.newInstance();
/**
* Construct a new {@code ProtobufHttpMessageConverter}.
*/
public ProtobufHttpMessageConverter() {
this(null);
}
/**
* Construct a new {@code ProtobufHttpMessageConverter} with a {@link ExtensionRegistryInitializer},
* allowing to register message extensions.
*/
public ProtobufHttpMessageConverter(ExtensionRegistryInitializer registryInitializer) {
//TODO: should we handle "*+json", "*+xml" as well?
super(PROTOBUF, MediaType.TEXT_PLAIN,
MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON);
Assert.notNull(registryInitializer, "ExtensionRegistryInitializer must not be null");
registryInitializer.initializeExtensionRegistry(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;
InputStreamReader reader = new InputStreamReader(inputMessage.getBody(), getCharset(inputMessage.getHeaders()));
try {
Message.Builder builder = createMessageBuilder(clazz);
if (MediaType.APPLICATION_JSON.isCompatibleWith(contentType)) {
JsonFormat.merge(reader, extensionRegistry, builder);
}
else if (MediaType.TEXT_PLAIN.isCompatibleWith(contentType)) {
TextFormat.merge(reader, extensionRegistry, builder);
}
else if (MediaType.APPLICATION_XML.isCompatibleWith(contentType)) {
XmlFormat.merge(reader, extensionRegistry, builder);
}
else { // ProtobufHttpMessageConverter.PROTOBUF
builder.mergeFrom(inputMessage.getBody(), 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 createMessageBuilder(Class<? extends Message> clazz) throws Exception {
Method m = newBuilderMethodCache.get(clazz);
if (m == null) {
m = clazz.getMethod("newBuilder");
newBuilderMethodCache.put(clazz, m);
}
return (Message.Builder) m.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 ContentType "application/x-protobuf"
*/
private void setProtoHeader(final HttpOutputMessage response, final 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;
}
}