code: /*
   * Copyright (C) 2008 Google Inc.
   *
   * Licensed 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 tools.com.google.gson;
  
  import java.lang.reflect.Type;
  
  /**
   * Interface representing a custom serializer for Json. You should write a custom serializer, if
   * you are not happy with the default serialization done by Gson. You will also need to register
   * this serializer through {@link com.google.gson.GsonBuilder#registerTypeAdapter(Type, Object)}.
   *
   * <p>Let us look at example where defining a serializer will be useful. The {@code Id} class
   * defined below has two fields: {@code clazz} and {@code value}.</p>
   *
   * <p><pre>
   * public class Id&lt;T&gt; {
   *   private final Class&lt;T&gt; clazz;
   *   private final long value;
   *
   *   public Id(Class&lt;T&gt; clazz, long value) {
   *     this.clazz = clazz;
   *     this.value = value;
   *   }
   *
   *   public long getValue() {
   *     return value;
   *   }
   * }
   * </pre></p>
   *
   * <p>The default serialization of {@code Id(com.foo.MyObject.class, 20L)} will be
   * <code>{"clazz":com.foo.MyObject,"value":20}</code>. Suppose, you just want the output to be
   * the value instead, which is {@code 20} in this case. You can achieve that by writing a custom
   * serializer:</p>
   *
   * <p><pre>
   * class IdSerializer implements JsonSerializer&lt;Id&gt;() {
   *   public JsonElement serialize(Id id, Type typeOfId, JsonSerializationContext context) {
   *     return new JsonPrimitive(id.getValue());
   *   }
   * }
   * </pre></p>
   *
   * <p>You will also need to register {@code IdSerializer} with Gson as follows:</p>
   * <pre>
   * Gson gson = new GsonBuilder().registerTypeAdapter(Id.class, new IdSerializer()).create();
   * </pre>
   *
   * <p>New applications should prefer {@link TypeAdapter}, whose streaming API
   * is more efficient than this interface's tree API.
   *
   * @author Inderjeet Singh
   * @author Joel Leitch
   *
   * @param <T> type for which the serializer is being registered. It is possible that a serializer
   *        may be asked to serialize a specific generic type of the T.
   */
  public interface JsonSerializer<T> {
  
    /**
     * Gson invokes this call-back method during serialization when it encounters a field of the
     * specified type.
     *
     * <p>In the implementation of this call-back method, you should consider invoking
     * {@link JsonSerializationContext#serialize(Object, Type)} method to create JsonElements for any
     * non-trivial field of the {@code src} object. However, you should never invoke it on the
     * {@code src} object itself since that will cause an infinite loop (Gson will call your
     * call-back method again).</p>
     *
     * @param src the object that needs to be converted to Json.
     * @param typeOfSrc the actual type (fully genericized version) of the source object.
     * @return a JsonElement corresponding to the specified object.
     */
    public JsonElement serialize(T src, Type typeOfSrc, JsonSerializationContext context);
  }
  