Java tutorial
/** * Copyright 2016-2017 Sixt GmbH & Co. Autovermietung KG * 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 com.sixt.service.framework.protobuf; import com.google.common.base.CaseFormat; import com.google.common.io.BaseEncoding; import com.google.gson.JsonArray; import com.google.gson.JsonElement; import com.google.gson.JsonObject; import com.google.gson.JsonPrimitive; import com.google.protobuf.ByteString; import com.google.protobuf.Descriptors; import com.google.protobuf.Message; import com.googlecode.protobuf.format.JsonFormat; import com.sixt.service.framework.rpc.RpcCallException; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.ByteArrayInputStream; import java.io.IOException; import java.lang.reflect.Constructor; import java.util.List; import java.util.Map; public class ProtobufUtil { public static final int MAX_HEADER_CHUNK_SIZE = 1000; public static final int MAX_BODY_CHUNK_SIZE = 10_000_000; private static final Logger logger = LoggerFactory.getLogger(ProtobufUtil.class); private static <TYPE extends Message> TYPE.Builder getBuilder(Class<TYPE> messageClass) throws NoSuchMethodException, InstantiationException, IllegalAccessException, java.lang.reflect.InvocationTargetException { Constructor<TYPE> constructor = messageClass.getDeclaredConstructor(); constructor.setAccessible(true); TYPE instance = constructor.newInstance(); return instance.newBuilderForType(); } /** * NOTE: this is only using the first element of the JsonArray */ public static Message jsonToProtobuf(JsonArray request, Class<? extends Message> messageClass) { return jsonToProtobuf(request.get(0).toString(), messageClass); } public static <TYPE extends Message> TYPE jsonToProtobuf(String request, Class<TYPE> messageClass) { try { TYPE.Builder builder = getBuilder(messageClass); JsonFormat formatter = new JsonFormat(); try { ByteArrayInputStream stream = new ByteArrayInputStream(request.getBytes()); formatter.merge(stream, builder); } catch (IOException e) { } return (TYPE) builder.build(); } catch (Exception e) { throw new RuntimeException("Error deserializing json to protobuf", e); } } public static <TYPE extends Message> TYPE byteArrayToProtobuf(byte data[], Class<TYPE> messageClass) throws RpcCallException { try { Message.Builder builder = getBuilder(messageClass); return (TYPE) builder.mergeFrom(data).build(); } catch (Exception e) { throw new RpcCallException(RpcCallException.Category.InternalServerError, "Error deserializing byte array to protobuf: " + e); } } public static <TYPE extends Message> TYPE newEmptyMessage(Class<TYPE> klass) { try { Message.Builder builder = getBuilder(klass); return (TYPE) builder.build(); } catch (Exception e) { throw new RuntimeException("Error deserializing byte array to protobuf", e); } } public static JsonObject protobufToJson(Message output) { JsonObject object = new JsonObject(); if (output == null) { logger.warn("Protobuf message was null"); } else { for (Map.Entry<Descriptors.FieldDescriptor, Object> field : output.getAllFields().entrySet()) { String jsonName = field.getKey().getName(); if (field.getKey().isRepeated()) { JsonArray array = new JsonArray(); List<?> items = (List<?>) field.getValue(); for (Object item : items) { array.add(serializeField(field.getKey(), item)); } object.add(jsonName, array); } else { object.add(jsonName, serializeField(field.getKey(), field.getValue())); } } } return object; } /** * Converts a JSON object to a protobuf message * * @param builder the proto message type builder * @param input the JSON object to convert */ public static Message fromJson(Message.Builder builder, JsonObject input) throws Exception { Descriptors.Descriptor descriptor = builder.getDescriptorForType(); for (Map.Entry<String, JsonElement> entry : input.entrySet()) { String protoName = CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, entry.getKey()); Descriptors.FieldDescriptor field = descriptor.findFieldByName(protoName); if (field == null) { throw new Exception("Can't find descriptor for field " + protoName); } if (field.isRepeated()) { if (!entry.getValue().isJsonArray()) { // fail } JsonArray array = entry.getValue().getAsJsonArray(); for (JsonElement item : array) { builder.addRepeatedField(field, parseField(field, item, builder)); } } else { builder.setField(field, parseField(field, entry.getValue(), builder)); } } return builder.build(); } private static JsonElement serializeField(Descriptors.FieldDescriptor field, Object value) { switch (field.getType()) { case DOUBLE: return new JsonPrimitive((Double) value); case FLOAT: return new JsonPrimitive((Float) value); case INT64: case UINT64: case FIXED64: case SINT64: case SFIXED64: return new JsonPrimitive((Long) value); case INT32: case UINT32: case FIXED32: case SINT32: case SFIXED32: return new JsonPrimitive((Integer) value); case BOOL: return new JsonPrimitive((Boolean) value); case STRING: return new JsonPrimitive((String) value); case GROUP: case MESSAGE: return protobufToJson((Message) value); case BYTES: return new JsonPrimitive(BaseEncoding.base64().encode(((ByteString) value).toByteArray())); case ENUM: String protoEnumName = ((Descriptors.EnumValueDescriptor) value).getName(); return new JsonPrimitive(protoEnumName); } return null; } private static Object parseField(Descriptors.FieldDescriptor field, JsonElement value, Message.Builder enclosingBuilder) throws Exception { switch (field.getType()) { case DOUBLE: if (!value.isJsonPrimitive()) { // fail; } return value.getAsDouble(); case FLOAT: if (!value.isJsonPrimitive()) { // fail; } return value.getAsFloat(); case INT64: case UINT64: case FIXED64: case SINT64: case SFIXED64: if (!value.isJsonPrimitive()) { // fail } return value.getAsLong(); case INT32: case UINT32: case FIXED32: case SINT32: case SFIXED32: if (!value.isJsonPrimitive()) { // fail } return value.getAsInt(); case BOOL: if (!value.isJsonPrimitive()) { // fail } return value.getAsBoolean(); case STRING: if (!value.isJsonPrimitive()) { // fail } return value.getAsString(); case GROUP: case MESSAGE: if (!value.isJsonObject()) { // fail } return fromJson(enclosingBuilder.newBuilderForField(field), value.getAsJsonObject()); case BYTES: if (!value.isJsonPrimitive()) { // fail } return ByteString.copyFrom(BaseEncoding.base64().decode(value.getAsString())); case ENUM: if (!value.isJsonPrimitive()) { // fail } String protoEnumValue = CaseFormat.LOWER_CAMEL.to(CaseFormat.UPPER_UNDERSCORE, value.getAsString()); return field.getEnumType().findValueByName(protoEnumValue); } return null; } }