org.springframework.messaging.converter.ProtobufMessageConverter Maven / Gradle / Ivy
/*
* Copyright 2002-2020 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.messaging.converter;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.lang.reflect.Method;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Map;
import com.google.protobuf.ExtensionRegistry;
import com.google.protobuf.Message;
import com.google.protobuf.util.JsonFormat;
import org.springframework.lang.Nullable;
import org.springframework.messaging.MessageHeaders;
import org.springframework.util.ClassUtils;
import org.springframework.util.ConcurrentReferenceHashMap;
import org.springframework.util.MimeType;
import static org.springframework.util.MimeTypeUtils.APPLICATION_JSON;
import static org.springframework.util.MimeTypeUtils.TEXT_PLAIN;
/**
* An {@code MessageConverter} that reads and writes
* {@link com.google.protobuf.Message com.google.protobuf.Messages} using
* Google Protocol Buffers.
*
* To generate {@code Message} Java classes, you need to install the {@code protoc} binary.
*
*
This converter supports by default {@code "application/x-protobuf"} with the official
* {@code "com.google.protobuf:protobuf-java"} library.
*
*
{@code "application/json"} can be supported with the official
* {@code "com.google.protobuf:protobuf-java-util"} 3.x, with 3.3 or higher recommended.
*
* @author Parviz Rozikov
* @author Rossen Stoyanchev
* @since 5.2.2
*/
public class ProtobufMessageConverter extends AbstractMessageConverter {
/**
* The default charset used by the converter.
*/
public static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
/**
* The mime-type for protobuf {@code application/x-protobuf}.
*/
public static final MimeType PROTOBUF = new MimeType("application", "x-protobuf", DEFAULT_CHARSET);
private static final Map, Method> methodCache = new ConcurrentReferenceHashMap<>();
final ExtensionRegistry extensionRegistry;
@Nullable
private final ProtobufFormatSupport protobufFormatSupport;
/**
* Constructor with a default instance of {@link ExtensionRegistry}.
*/
public ProtobufMessageConverter() {
this(null, null);
}
/**
* Constructor with a given {@code ExtensionRegistry}.
*/
public ProtobufMessageConverter(ExtensionRegistry extensionRegistry) {
this(null, extensionRegistry);
}
ProtobufMessageConverter(@Nullable ProtobufFormatSupport formatSupport,
@Nullable ExtensionRegistry extensionRegistry) {
super(PROTOBUF, TEXT_PLAIN);
if (formatSupport != null) {
this.protobufFormatSupport = formatSupport;
}
else if (ClassUtils.isPresent("com.google.protobuf.util.JsonFormat", getClass().getClassLoader())) {
this.protobufFormatSupport = new ProtobufJavaUtilSupport(null, null);
}
else {
this.protobufFormatSupport = null;
}
if (this.protobufFormatSupport != null) {
addSupportedMimeTypes(this.protobufFormatSupport.supportedMediaTypes());
}
this.extensionRegistry = (extensionRegistry == null ? ExtensionRegistry.newInstance() : extensionRegistry);
}
@Override
protected boolean supports(Class clazz) {
return Message.class.isAssignableFrom(clazz);
}
@Override
protected boolean canConvertTo(Object payload, @Nullable MessageHeaders headers) {
MimeType contentType = getMimeType(headers);
return (super.canConvertTo(payload, headers) ||
this.protobufFormatSupport != null && this.protobufFormatSupport.supportsWriteOnly(contentType));
}
@Override
protected Object convertFromInternal(org.springframework.messaging.Message message,
Class targetClass, @Nullable Object conversionHint) {
MimeType contentType = getMimeType(message.getHeaders());
final Object payload = message.getPayload();
if (contentType == null) {
contentType = PROTOBUF;
}
Charset charset = contentType.getCharset();
if (charset == null) {
charset = DEFAULT_CHARSET;
}
Message.Builder builder = getMessageBuilder(targetClass);
try {
if (PROTOBUF.isCompatibleWith(contentType)) {
builder.mergeFrom((byte[]) payload, this.extensionRegistry);
}
else if (this.protobufFormatSupport != null) {
this.protobufFormatSupport.merge(message, charset, contentType, this.extensionRegistry, builder);
}
}
catch (IOException ex) {
throw new MessageConversionException(message, "Could not read proto message" + ex.getMessage(), ex);
}
return builder.build();
}
@Override
protected Object convertToInternal(
Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint) {
final Message message = (Message) payload;
MimeType contentType = getMimeType(headers);
if (contentType == null) {
contentType = PROTOBUF;
}
Charset charset = contentType.getCharset();
if (charset == null) {
charset = DEFAULT_CHARSET;
}
try {
if (PROTOBUF.isCompatibleWith(contentType)) {
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
message.writeTo(byteArrayOutputStream);
payload = byteArrayOutputStream.toByteArray();
}
else if (this.protobufFormatSupport != null) {
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
this.protobufFormatSupport.print(message, outputStream, contentType, charset);
payload = outputStream.toString(charset.name());
}
}
catch (IOException ex) {
throw new MessageConversionException("Failed to print Protobuf message: " + ex.getMessage(), ex);
}
return payload;
}
/**
* Create a new {@code Message.Builder} instance for the given class.
* This method uses a ConcurrentReferenceHashMap for caching method lookups.
*/
private Message.Builder getMessageBuilder(Class clazz) {
try {
Method method = methodCache.get(clazz);
if (method == null) {
method = clazz.getMethod("newBuilder");
methodCache.put(clazz, method);
}
return (Message.Builder) method.invoke(clazz);
}
catch (Exception ex) {
throw new MessageConversionException(
"Invalid Protobuf Message type: no invocable newBuilder() method on " + clazz, ex);
}
}
/**
* Protobuf format support.
*/
interface ProtobufFormatSupport {
MimeType[] supportedMediaTypes();
boolean supportsWriteOnly(@Nullable MimeType mediaType);
void merge(org.springframework.messaging.Message message,
Charset charset, MimeType contentType, ExtensionRegistry extensionRegistry,
Message.Builder builder) throws IOException, MessageConversionException;
void print(Message message, OutputStream output, MimeType contentType, Charset charset)
throws IOException, MessageConversionException;
}
/**
* {@link ProtobufFormatSupport} implementation used when
* {@code com.google.protobuf.util.JsonFormat} is available.
*/
static class ProtobufJavaUtilSupport implements ProtobufFormatSupport {
private final JsonFormat.Parser parser;
private final JsonFormat.Printer printer;
public ProtobufJavaUtilSupport(@Nullable JsonFormat.Parser parser, @Nullable JsonFormat.Printer printer) {
this.parser = (parser != null ? parser : JsonFormat.parser());
this.printer = (printer != null ? printer : JsonFormat.printer());
}
@Override
public MimeType[] supportedMediaTypes() {
return new MimeType[]{APPLICATION_JSON};
}
@Override
public boolean supportsWriteOnly(@Nullable MimeType mimeType) {
return false;
}
@Override
public void merge(org.springframework.messaging.Message message, Charset charset,
MimeType contentType, ExtensionRegistry extensionRegistry, Message.Builder builder)
throws IOException, MessageConversionException {
if (contentType.isCompatibleWith(APPLICATION_JSON)) {
this.parser.merge(message.getPayload().toString(), builder);
}
else {
throw new MessageConversionException(
"protobuf-java-util does not support parsing " + contentType);
}
}
@Override
public void print(Message message, OutputStream output, MimeType contentType, Charset charset)
throws IOException, MessageConversionException {
if (contentType.isCompatibleWith(APPLICATION_JSON)) {
OutputStreamWriter writer = new OutputStreamWriter(output, charset);
this.printer.appendTo(message, writer);
writer.flush();
}
else {
throw new MessageConversionException(
"protobuf-java-util does not support printing " + contentType);
}
}
}
}