JsonSectionAdapter.java

package com.urise.webapp.util;

import com.google.gson.*;

import java.lang.reflect.Type;

public class JsonSectionAdapter<T> implements JsonSerializer<T>, JsonDeserializer<T> {
    private static final String CLASSNAME = "CLASSNAME";
    private static final String INSTANCE = "INSTANCE";

    @Override
    public T deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext context) throws JsonParseException {
        JsonObject jsonObject = jsonElement.getAsJsonObject();
        //считываем свойство CLASSNAME - имя класса
        JsonPrimitive prim = (JsonPrimitive) jsonObject.get(CLASSNAME);
        String className = prim.getAsString();
        try{
            Class clazz = Class.forName(className);
            return context.deserialize(jsonObject.get(INSTANCE),clazz);
        } catch (ClassNotFoundException e) {
            throw new JsonParseException(e.getMessage());
        }
    }

    @Override
    public JsonElement serialize(T section, Type type, JsonSerializationContext context) {
        JsonObject retValue =new JsonObject();
        //добавляем свойство classname
        retValue.addProperty(CLASSNAME, section.getClass().getName());
        //сериализуем инстанс
        JsonElement elem =context.serialize(section);
        //добавляем инстанс
        retValue.add(INSTANCE,elem);
        return retValue;
    }
}