com.balajeetm.mystique.util.gson.GsonFactory.java Source code

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Here is the source code for com.balajeetm.mystique.util.gson.GsonFactory.java

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/*
 * Copyright (c) Balajee TM 2017.
 * All rights reserved.
 * License -  @see <a href="http://www.apache.org/licenses/LICENSE-2.0"></a>
 */

/*
 * Created on 20 Oct, 2017 by balajeemohan
 * http://www.balajeetm.com
 */
package com.balajeetm.mystique.util.gson;

import java.lang.reflect.Type;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.xml.datatype.XMLGregorianCalendar;

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.JsonParseException;
import com.google.gson.JsonParser;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;

/**
 * A factory for creating Gson objects.
 *
 * @author balajeemohan
 */
public class GsonFactory {

    /** The json parser. */
    private JsonParser jsonParser;

    /** The gson. */
    private Gson gson;

    /** The gson builder. */
    private GsonBuilder gsonBuilder;

    /**
     * Gets the single instance of GsonFactory.
     *
     * @return single instance of GsonFactory
     */
    public static GsonFactory getInstance() {
        return Creator.INSTANCE;
    }

    // Efficient Thread safe Lazy Initialization
    // works only if the singleton constructor is non parameterized
    /** The Class Creator. */
    private static class Creator {

        /** The instance. */
        private static GsonFactory INSTANCE = new GsonFactory();
    }

    /** Instantiates a new gson factory. */
    private GsonFactory() {
    }

    /**
     * Gets the json parser.
     *
     * @return the json parser
     */
    public JsonParser getJsonParser() {
        if (null == jsonParser) {
            jsonParser = new JsonParser();
        }
        return jsonParser;
    }

    /**
     * Gets the gson.
     *
     * @return the gson
     */
    public Gson getGson() {
        if (null == gson) {
            gson = getGsonBuilder().create();
        }
        return gson;
    }

    /**
     * Gets the gson builder.
     *
     * @return the gson builder
     */
    public GsonBuilder getGsonBuilder() {
        if (null == gsonBuilder) {
            gsonBuilder = new GsonBuilder();
            gsonBuilder.setDateFormat(DateFormat.LONG, DateFormat.LONG);
            gsonBuilder.registerTypeAdapter(Date.class, new JsonDeserializer<Date>() {

                @Override
                public Date deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
                        throws JsonParseException {
                    Date date = null;
                    if (null != json && json.isJsonPrimitive()) {
                        date = new Date(json.getAsJsonPrimitive().getAsLong());
                    }
                    return date;
                }
            });
            gsonBuilder.registerTypeAdapter(XMLGregorianCalendar.class, new JsonSerializer<XMLGregorianCalendar>() {

                @Override
                public JsonElement serialize(XMLGregorianCalendar src, Type typeOfSrc,
                        JsonSerializationContext context) {
                    Date date = null;
                    if (null != src) {
                        date = src.toGregorianCalendar().getTime();
                    }
                    return new JsonPrimitive(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ").format(date));
                }
            });
        }
        return gsonBuilder;
    }
}