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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* 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.
* ============LICENSE_END=========================================================
*/
package org.onap.policy.common.gson;
import com.google.gson.Gson;
import com.google.gson.TypeAdapter;
import com.google.gson.TypeAdapterFactory;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;
import java.io.IOException;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;
/**
* Adapter factory for Map<String,Object> and List<String>. By default, GSON treats all Objects, that
* are numbers, as Double. This recursively walks a map/list and converts Doubles to Integer or Long, if
* possible.
*/
public class MapDoubleAdapterFactory implements TypeAdapterFactory {
@Override
public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
if (!isMapType(type) && !isListType(type)) {
return null;
}
TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
return new MapAdapter<>(delegate);
}
private <T> boolean isMapType(TypeToken<T> type) {
if (!Map.class.isAssignableFrom(type.getRawType())) {
return false;
}
// only supports Map<String,Object>
if (!(type.getType() instanceof ParameterizedType)) {
// untyped - assume the parameters are the correct type
return true;
}
Type[] actualParams = ((ParameterizedType) type.getType()).getActualTypeArguments();
return (actualParams[0] == String.class && actualParams[1] == Object.class);
}
private <T> boolean isListType(TypeToken<T> type) {
if (!List.class.isAssignableFrom(type.getRawType())) {
return false;
}
// only supports List<Object>
if (!(type.getType() instanceof ParameterizedType)) {
// untyped - assume the parameters are the correct type
return true;
}
Type[] actualParams = ((ParameterizedType) type.getType()).getActualTypeArguments();
return (actualParams[0] == Object.class);
}
/**
* Type adapter that performs conversion from Double to Integer/Long.
*
* @param <T> type of object on which this works (always Map.class)
*/
private static class MapAdapter<T> extends TypeAdapter<T> {
/**
* Used to perform conversion between JSON and Map<String,Object>.
*/
private final TypeAdapter<T> delegate;
/**
* Constructs the object.
*
* @param delegate JSON/Map converter
*/
public MapAdapter(TypeAdapter<T> delegate) {
this.delegate = delegate;
}
@Override
public void write(JsonWriter out, T value) throws IOException {
delegate.write(out, value);
}
@Override
public T read(JsonReader in) throws IOException {
T value = delegate.read(in);
DoubleConverter.convertFromDouble(value);
return value;
}
}
}
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