2011-05-14 04:04:17 +02:00
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/*
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* Copyright (C) 2011 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.gson.typeadapters;
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import com.google.gson.JsonDeserializationContext;
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import com.google.gson.JsonDeserializer;
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import com.google.gson.JsonElement;
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import com.google.gson.JsonObject;
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import com.google.gson.JsonParseException;
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import com.google.gson.JsonPrimitive;
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import com.google.gson.JsonSerializationContext;
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import com.google.gson.JsonSerializer;
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import java.lang.reflect.Type;
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import java.util.LinkedHashMap;
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import java.util.Map;
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public final class RuntimeTypeAdapter<T>
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implements JsonSerializer<T>, JsonDeserializer<T> {
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private final Class<?> baseType;
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private final String typeFieldName;
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private final Map<String, Class<?>> labelToSubtype = new LinkedHashMap<String, Class<?>>();
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private final Map<Class<?>, String> subtypeToLabel = new LinkedHashMap<Class<?>, String>();
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public RuntimeTypeAdapter(Class<?> baseType, String typeFieldName) {
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this.baseType = baseType;
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this.typeFieldName = typeFieldName;
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}
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public static <T> RuntimeTypeAdapter<T> create(Class<T> c) {
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return new RuntimeTypeAdapter<T>(c, "type");
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}
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public static <T> RuntimeTypeAdapter<T> create(Class<T> c, String typeFieldName) {
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return new RuntimeTypeAdapter<T>(c, typeFieldName);
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}
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2011-05-27 20:47:31 +02:00
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public RuntimeTypeAdapter<T> registerSubtype(Class<? extends T> type, String label) {
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2011-05-14 04:04:17 +02:00
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if (subtypeToLabel.containsKey(type) || labelToSubtype.containsKey(label)) {
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throw new IllegalArgumentException("types and labels must be unique");
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}
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labelToSubtype.put(label, type);
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subtypeToLabel.put(type, label);
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2011-05-27 20:47:31 +02:00
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return this;
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2011-05-14 04:04:17 +02:00
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}
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2011-05-27 20:47:31 +02:00
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public RuntimeTypeAdapter<T> registerSubtype(Class<? extends T> type) {
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return registerSubtype(type, type.getSimpleName());
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2011-05-14 04:04:17 +02:00
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}
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public JsonElement serialize(T src, Type typeOfSrc, JsonSerializationContext context) {
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Class<?> srcType = src.getClass();
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String label = subtypeToLabel.get(srcType);
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if (label == null) {
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throw new IllegalArgumentException("cannot serialize " + srcType.getName()
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+ "; did you forget to register a subtype?");
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}
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JsonElement serialized = context.serialize(src, srcType);
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final JsonObject jsonObject = serialized.getAsJsonObject();
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if (jsonObject.has(typeFieldName)) {
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throw new IllegalArgumentException("cannot serialize " + srcType.getName()
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+ " because it already defines a field named " + typeFieldName);
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}
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JsonObject clone = new JsonObject();
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clone.add(typeFieldName, new JsonPrimitive(label));
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for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
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clone.add(e.getKey(), e.getValue());
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}
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return clone;
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}
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public T deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
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throws JsonParseException {
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JsonElement labelJsonElement = json.getAsJsonObject().remove(typeFieldName);
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if (labelJsonElement == null) {
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throw new JsonParseException("cannot deserialize " + typeOfT
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+ " because it does not define a field named " + typeFieldName);
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}
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String label = labelJsonElement.getAsString();
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Class<?> subtype = labelToSubtype.get(label);
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if (subtype == null) {
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throw new JsonParseException("cannot deserialize " + baseType + " subtype named "
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+ label + "; did you forget to register a subtype?");
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}
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@SuppressWarnings("unchecked") // registration requires that subtype extends T
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T result = (T) context.deserialize(json, subtype);
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return result;
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}
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}
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