com.jamierf.persistenthashmap.serializers.GsonSerializer.java Source code

Introduction

Here is the source code for com.jamierf.persistenthashmap.serializers.GsonSerializer.java

Source

/**
 *
 * This file is part of the Persistent-HashMap library.
 * Copyright (C) 2010 George Haney (http://www.georgemh.com)
 * License: http://www.gnu.org/licenses/gpl.html GPL version 3 (or higher)
 *
 */

package com.jamierf.persistenthashmap.serializers;

import java.io.File;
import java.io.IOException;
import java.io.Serializable;
import java.lang.reflect.Type;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
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.jamierf.persistenthashmap.util.FileUtils;

public class GsonSerializer implements ObjectSerializer {

    protected Gson gson;

    public GsonSerializer() {
        GsonBuilder builder = new GsonBuilder();
        builder.registerTypeAdapter(ObjectContainer.class, new GenericTypeAdapter());
        builder.setDateFormat("yyMMddHHmmssSSSZ");
        gson = builder.create();
    }

    public Object readObject(File f) throws IOException {
        String data = FileUtils.getGZIPContents(f);
        return gson.fromJson(data, ObjectContainer.class).getValue();
    }

    public void writeObject(File f, Serializable o, boolean force) throws IOException {
        String data = gson.toJson(new ObjectContainer(o));
        FileUtils.putGZIPContents(f, data, force);
    }

    protected class ObjectContainer {
        protected String valueType;
        protected Object value;

        public ObjectContainer(Object obj) {
            valueType = obj.getClass().getName();
            value = obj;
        }

        public String getValueType() {
            return valueType;
        }

        public Object getValue() {
            return value;
        }
    }

    protected class GenericTypeAdapter
            implements JsonDeserializer<ObjectContainer>, JsonSerializer<ObjectContainer> {
        public JsonElement serialize(ObjectContainer value, Type arg1, JsonSerializationContext context) {
            JsonObject json = new JsonObject();

            json.addProperty("valueType", value.getValueType());
            json.add("value", context.serialize(value.getValue()));

            return json;
        }

        public ObjectContainer deserialize(JsonElement jsonElem, Type type, JsonDeserializationContext context)
                throws JsonParseException {
            if (!jsonElem.isJsonObject()) {
                throw new JsonParseException("Did not receive a JsonObject!");
            }

            JsonObject json = jsonElem.getAsJsonObject();
            String valueType = json.get("valueType").getAsString();

            Class<?> clazz;
            try {
                clazz = Class.forName(valueType);
            } catch (ClassNotFoundException e) {
                throw new JsonParseException("Unable to find Type: " + valueType);
            }

            return new ObjectContainer(context.deserialize(json.get("value"), clazz));
        }
    }
}