org.ambraproject.rhino.util.JsonAdapterUtil.java Source code

Introduction

Here is the source code for org.ambraproject.rhino.util.JsonAdapterUtil.java

Source

/*
 * Copyright (c) 2017 Public Library of Science
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

package org.ambraproject.rhino.util;

import com.google.common.base.Preconditions;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import org.ambraproject.rhombat.gson.Iso8601CalendarAdapter;
import org.ambraproject.rhombat.gson.Iso8601DateAdapter;
import org.hibernate.proxy.HibernateProxy;

import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Map;

public final class JsonAdapterUtil {
    private JsonAdapterUtil() {
        throw new AssertionError("Not instantiable");
    }

    /**
     * Copy all members that aren't already present.
     *
     * @param source      the object to copy from
     * @param destination the object to copy members to
     * @return {@code destination}
     */
    public static JsonObject copyWithoutOverwriting(JsonObject source, JsonObject destination) {
        Preconditions.checkNotNull(destination);
        for (Map.Entry<String, JsonElement> fromEntry : source.entrySet()) {
            String key = fromEntry.getKey();
            if (!destination.has(key)) {
                destination.add(key, fromEntry.getValue());
            }
        }
        return destination;
    }

    /**
     * Create a {@code GsonBuilder} preconfigured with utility adapters.
     *
     * @return a {@code GsonBuilder} object
     */
    public static GsonBuilder makeGsonBuilder() {
        GsonBuilder builder = new GsonBuilder();

        builder.registerTypeAdapter(Date.class, new Iso8601DateAdapter());
        Iso8601CalendarAdapter calendarAdapter = new Iso8601CalendarAdapter();
        builder.registerTypeAdapter(Calendar.class, calendarAdapter);
        builder.registerTypeAdapter(GregorianCalendar.class, calendarAdapter);

        return builder;
    }

    /**
     * If the object is a lazy-loaded HibernateProxy, force it to be replaced with its actual write-replacement. This can
     * be used to work around Hibernate optimizations that disrupt Gson's automatic serialization.
     * <p/>
     * This may incur extra performance costs if the full object would not have otherwise been read.
     *
     * @param object     a Hibernate model entity, which may be lazy-loaded
     * @param classToken the model type
     * @param <T>        the model type
     * @return a non-lazy-loading instance of the entity
     * @see org.hibernate.proxy.HibernateProxy#writeReplace()
     */
    public static <T> T forceHibernateLazyLoad(T object, Class<T> classToken) {
        Preconditions.checkNotNull(classToken);
        if (object instanceof HibernateProxy) {
            HibernateProxy hibernateProxy = (HibernateProxy) object;
            return classToken.cast(hibernateProxy.writeReplace());
        }
        return object;
    }

}