WatermarkSerializerHelper.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

package gobblin.source.extractor;

import com.google.gson.Gson;
import com.google.gson.JsonElement;

/**
 * Provides default implementation for converting a {@link Watermark} to a {@link JsonElement}, and vice versa. The
 * class uses <a href="https://code.google.com/p/google-gson/">GSON</a> to achieve this. This class provides a default
 * way to serialize and de-serialize {@link Watermark}s, and is useful for implementing the {@link Watermark#toJson()}
 * method.
 */
public class WatermarkSerializerHelper {

  private static final Gson GSON = new Gson();

  /**
   * Converts a {@link Watermark} to a {@link JsonElement} using the {@link Gson#toJsonTree(Object)} method.
   *
   * @param watermark the {@link Watermark} that needs to be converted to json.
   * @return a {@link JsonElement} that represents the given {@link Watermark}.
   */
  public static JsonElement convertWatermarkToJson(Watermark watermark) {
    return GSON.toJsonTree(watermark);
  }

  /**
   * Converts a {@link JsonElement} into the specified class type using the {@link Gson#fromJson(JsonElement, Class)}
   * method.
   *
   * @param jsonElement is a {@link JsonElement} that will be converted into a {@link Watermark}.
   * @param clazz is the {@link Class} that the {@link JsonElement} will be converted into.
   * @return an instance of a class that extends {@link Watermark}.
   */
  public static <T extends Watermark> T convertJsonToWatermark(JsonElement jsonElement, Class<T> clazz) {
    return GSON.fromJson(jsonElement, clazz);
  }
}