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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2019, 2021 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.internal;
import com.google.gson.Gson;
import com.google.gson.JsonElement;
import com.google.gson.TypeAdapter;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;
import java.io.IOException;
import java.util.List;
/**
* Adapter for a single class that implements a jackson-style behavior.
*
* @param <T> type of class on which the adapter works
*/
public class JacksonTypeAdapter<T> extends TypeAdapter<T> {
/**
* Used to create an object of the given class.
*/
private final TypeAdapter<T> delegate;
/**
* Used to serialize/deserialize a JsonElement.
*/
private final TypeAdapter<JsonElement> elementAdapter;
/**
* Serializers for each item within the object.
*/
private final Serializer[] serializers;
/**
* Deserializers for each item within the object.
*/
private final Deserializer[] deserializers;
/**
* Constructs the object.
*
* @param gson the associated gson object
* @param delegate default constructor for the type
* @param serializers the serializers to use to serialize items within the object
* @param deserializers the deserializers to use to deserialize items into the object
*/
public JacksonTypeAdapter(Gson gson, TypeAdapter<T> delegate, List<Serializer> serializers,
List<Deserializer> deserializers) {
this.delegate = delegate;
this.elementAdapter = gson.getAdapter(JsonElement.class);
this.serializers = serializers.toArray(new Serializer[0]);
this.deserializers = deserializers.toArray(new Deserializer[0]);
}
@Override
public void write(JsonWriter out, T value) throws IOException {
JsonElement tree = delegate.toJsonTree(value);
if (tree.isJsonObject()) {
var jsonObj = tree.getAsJsonObject();
// serialize each item from the value into the target tree
for (Serializer serializer : serializers) {
serializer.addToTree(value, jsonObj);
}
}
elementAdapter.write(out, tree);
}
@Override
public T read(JsonReader in) throws IOException {
JsonElement tree = elementAdapter.read(in);
var object = delegate.fromJsonTree(tree);
if (tree.isJsonObject()) {
var jsonObj = tree.getAsJsonObject();
// deserialize each item from the tree into the target object
for (Deserializer dser : deserializers) {
dser.getFromTree(jsonObj, object);
}
}
return object;
}
}
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