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/*
* Copyright (C) 2010 Google Inc.
*
* 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.google.gson.protobuf;
import com.google.gson.JsonArray;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;
import com.google.protobuf.Descriptors.Descriptor;
import com.google.protobuf.Descriptors.FieldDescriptor;
import com.google.protobuf.GeneratedMessage;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Gson type adapter for protocol buffers
*
* @author Inderjeet Singh
*/
public class ProtoTypeAdapter implements JsonSerializer<GeneratedMessage>,
JsonDeserializer<GeneratedMessage> {
@Override
public JsonElement serialize(GeneratedMessage src, Type typeOfSrc,
JsonSerializationContext context) {
JsonObject ret = new JsonObject();
final Map<FieldDescriptor, Object> fields = src.getAllFields();
for (Map.Entry<FieldDescriptor, Object> fieldPair : fields.entrySet()) {
final FieldDescriptor desc = fieldPair.getKey();
if (desc.isRepeated()) {
List<?> fieldList = (List<?>) fieldPair.getValue();
if (fieldList.size() != 0) {
JsonArray array = new JsonArray();
for (Object o : fieldList) {
array.add(context.serialize(o));
}
ret.add(desc.getName(), array);
}
} else {
ret.add(desc.getName(), context.serialize(fieldPair.getValue()));
}
}
return ret;
}
@SuppressWarnings("unchecked")
@Override
public GeneratedMessage deserialize(JsonElement json, Type typeOfT,
JsonDeserializationContext context) throws JsonParseException {
try {
JsonObject jsonObject = json.getAsJsonObject();
Class<? extends GeneratedMessage> protoClass =
(Class<? extends GeneratedMessage>) typeOfT;
try {
// Invoke the ProtoClass.newBuilder() method
Object protoBuilder = getCachedMethod(protoClass, "newBuilder")
.invoke(null);
Class<?> builderClass = protoBuilder.getClass();
Descriptor protoDescriptor = (Descriptor) getCachedMethod(
protoClass, "getDescriptor").invoke(null);
// Call setters on all of the available fields
for (FieldDescriptor fieldDescriptor : protoDescriptor.getFields()) {
String name = fieldDescriptor.getName();
if (jsonObject.has(name)) {
JsonElement jsonElement = jsonObject.get(name);
String fieldName = name + "_";
Field field = protoClass.getDeclaredField(fieldName);
Type fieldType = field.getGenericType();
Object fieldValue = context.deserialize(jsonElement, fieldType);
Method method = getCachedMethod(
builderClass, "setField", FieldDescriptor.class, Object.class);
method.invoke(protoBuilder, fieldDescriptor, fieldValue);
}
}
// Invoke the build method to return the final proto
return (GeneratedMessage) getCachedMethod(builderClass, "build")
.invoke(protoBuilder);
} catch (SecurityException e) {
throw new JsonParseException(e);
} catch (NoSuchMethodException e) {
throw new JsonParseException(e);
} catch (IllegalArgumentException e) {
throw new JsonParseException(e);
} catch (IllegalAccessException e) {
throw new JsonParseException(e);
} catch (InvocationTargetException e) {
throw new JsonParseException(e);
}
} catch (Exception e) {
throw new JsonParseException("Error while parsing proto: ", e);
}
}
private static Method getCachedMethod(Class<?> clazz, String methodName,
Class<?>... methodParamTypes) throws NoSuchMethodException {
Map<Class<?>, Method> mapOfMethods = mapOfMapOfMethods.get(methodName);
if (mapOfMethods == null) {
mapOfMethods = new HashMap<Class<?>, Method>();
mapOfMapOfMethods.put(methodName, mapOfMethods);
}
Method method = mapOfMethods.get(clazz);
if (method == null) {
method = clazz.getMethod(methodName, methodParamTypes);
mapOfMethods.put(clazz, method);
}
return method;
}
private static Map<String, Map<Class<?>, Method>> mapOfMapOfMethods =
new HashMap<String, Map<Class<?>, Method>>();
}
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