java-design-patterns/tolerant-reader/src/main/java/com/iluwatar/tolerantreader/RainbowFishSerializer.java

/**
 * The MIT License
 * Copyright (c) 2014 Ilkka Seppälä
 *
 * 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 com.iluwatar.tolerantreader;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.HashMap;
import java.util.Map;

/**
 * 
 * RainbowFishSerializer provides methods for reading and writing {@link RainbowFish} objects to
 * file. Tolerant Reader pattern is implemented here by serializing maps instead of
 * {@link RainbowFish} objects. This way the reader does not break even though new properties are
 * added to the schema.
 *
 */
public class RainbowFishSerializer {

  private RainbowFishSerializer() {
  }

  /**
   * Write V1 RainbowFish to file
   */
  public static void writeV1(RainbowFish rainbowFish, String filename) throws IOException {
    Map<String, String> map = new HashMap<>();
    map.put("name", rainbowFish.getName());
    map.put("age", String.format("%d", rainbowFish.getAge()));
    map.put("lengthMeters", String.format("%d", rainbowFish.getLengthMeters()));
    map.put("weightTons", String.format("%d", rainbowFish.getWeightTons()));
    FileOutputStream fileOut = new FileOutputStream(filename);
    ObjectOutputStream objOut = new ObjectOutputStream(fileOut);
    objOut.writeObject(map);
    objOut.close();
    fileOut.close();
  }

  /**
   * Write V2 RainbowFish to file
   */
  public static void writeV2(RainbowFishV2 rainbowFish, String filename) throws IOException {
    Map<String, String> map = new HashMap<>();
    map.put("name", rainbowFish.getName());
    map.put("age", String.format("%d", rainbowFish.getAge()));
    map.put("lengthMeters", String.format("%d", rainbowFish.getLengthMeters()));
    map.put("weightTons", String.format("%d", rainbowFish.getWeightTons()));
    map.put("angry", Boolean.toString(rainbowFish.getAngry()));
    map.put("hungry", Boolean.toString(rainbowFish.getHungry()));
    map.put("sleeping", Boolean.toString(rainbowFish.getSleeping()));
    FileOutputStream fileOut = new FileOutputStream(filename);
    ObjectOutputStream objOut = new ObjectOutputStream(fileOut);
    objOut.writeObject(map);
    objOut.close();
    fileOut.close();
  }

  /**
   * Read V1 RainbowFish from file
   */
  public static RainbowFish readV1(String filename) throws IOException, ClassNotFoundException {
    FileInputStream fileIn = new FileInputStream(filename);
    ObjectInputStream objIn = new ObjectInputStream(fileIn);
    Map<String, String> map = (Map<String, String>) objIn.readObject();
    objIn.close();
    fileIn.close();
    return new RainbowFish(map.get("name"), Integer.parseInt(map.get("age")), Integer.parseInt(map
        .get("lengthMeters")), Integer.parseInt(map.get("weightTons")));
  }
}