88
src/org/mcteam/ancientgates/gson/JsonDeserializer.java
Normal file
88
src/org/mcteam/ancientgates/gson/JsonDeserializer.java
Normal file
@ -0,0 +1,88 @@
|
||||
/*
|
||||
* 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 org.mcteam.ancientgates.gson;
|
||||
|
||||
import java.lang.reflect.Type;
|
||||
|
||||
/**
|
||||
* <p>Interface representing a custom deserializer for Json. You should write a custom
|
||||
* deserializer, if you are not happy with the default deserialization done by Gson. You will
|
||||
* also need to register this deserializer through
|
||||
* {@link GsonBuilder#registerTypeAdapter(Type, Object)}.</p>
|
||||
*
|
||||
* <p>Let us look at example where defining a deserializer will be useful. The {@code Id} class
|
||||
* defined below has two fields: {@code clazz} and {@code value}.</p>
|
||||
*
|
||||
* <pre>
|
||||
* public class Id<T> {
|
||||
* private final Class<T> clazz;
|
||||
* private final long value;
|
||||
* public Id(Class<T> clazz, long value) {
|
||||
* this.clazz = clazz;
|
||||
* this.value = value;
|
||||
* }
|
||||
* public long getValue() {
|
||||
* return value;
|
||||
* }
|
||||
* }
|
||||
* </pre>
|
||||
*
|
||||
* <p>The default deserialization of {@code Id(com.foo.MyObject.class, 20L)} will require the
|
||||
* Json string to be <code>{"clazz":com.foo.MyObject,"value":20}</code>. Suppose, you already know
|
||||
* the type of the field that the {@code Id} will be deserialized into, and hence just want to
|
||||
* deserialize it from a Json string {@code 20}. You can achieve that by writing a custom
|
||||
* deserializer:</p>
|
||||
*
|
||||
* <pre>
|
||||
* class IdDeserializer implements JsonDeserializer<Id>() {
|
||||
* public Id fromJson(JsonElement json, Type typeOfT, JsonDeserializationContext context)
|
||||
* throws JsonParseException {
|
||||
* return (Id) new Id((Class)typeOfT, id.getValue());
|
||||
* }
|
||||
* </pre>
|
||||
*
|
||||
* <p>You will also need to register {@code IdDeserializer} with Gson as follows:</p>
|
||||
*
|
||||
* <pre>
|
||||
* Gson gson = new GsonBuilder().registerTypeAdapter(Id.class, new IdDeserializer()).create();
|
||||
* </pre>
|
||||
*
|
||||
* @author Inderjeet Singh
|
||||
* @author Joel Leitch
|
||||
*
|
||||
* @param <T> type for which the deserializer is being registered. It is possible that a
|
||||
* deserializer may be asked to deserialize a specific generic type of the T.
|
||||
*/
|
||||
public interface JsonDeserializer<T> {
|
||||
|
||||
/**
|
||||
* Gson invokes this call-back method during deserialization when it encounters a field of the
|
||||
* specified type.
|
||||
* <p>In the implementation of this call-back method, you should consider invoking
|
||||
* {@link JsonDeserializationContext#deserialize(JsonElement, Type)} method to create objects
|
||||
* for any non-trivial field of the returned object. However, you should never invoke it on the
|
||||
* the same type passing {@code json} since that will cause an infinite loop (Gson will call your
|
||||
* call-back method again).
|
||||
*
|
||||
* @param json The Json data being deserialized
|
||||
* @param typeOfT The type of the Object to deserialize to
|
||||
* @return a deserialized object of the specified type typeOfT which is a subclass of {@code T}
|
||||
* @throws JsonParseException if json is not in the expected format of {@code typeofT}
|
||||
*/
|
||||
public T deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
|
||||
throws JsonParseException;
|
||||
}
|
Reference in New Issue
Block a user