| // Copyright (C) 2022 The Android Open Source Project |
| // |
| // 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 com.google.gerrit.json; |
| |
| import com.google.gson.JsonDeserializationContext; |
| import com.google.gson.JsonDeserializer; |
| import com.google.gson.JsonElement; |
| import com.google.gson.JsonNull; |
| import com.google.gson.JsonObject; |
| import com.google.gson.JsonParseException; |
| import com.google.gson.JsonSerializationContext; |
| import com.google.gson.JsonSerializer; |
| import com.google.inject.TypeLiteral; |
| import java.lang.reflect.ParameterizedType; |
| import java.lang.reflect.Type; |
| import java.util.Optional; |
| |
| public class OptionalTypeAdapter |
| implements JsonSerializer<Optional<?>>, JsonDeserializer<Optional<?>> { |
| |
| private static final String VALUE = "value"; |
| |
| @Override |
| public JsonElement serialize(Optional<?> src, Type typeOfSrc, JsonSerializationContext context) { |
| Optional<?> optional = src == null ? Optional.empty() : src; |
| JsonObject json = new JsonObject(); |
| json.add(VALUE, optional.map(context::serialize).orElse(JsonNull.INSTANCE)); |
| return json; |
| } |
| |
| @Override |
| public Optional<?> deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) |
| throws JsonParseException { |
| if (!json.getAsJsonObject().has(VALUE)) { |
| return Optional.empty(); |
| } |
| |
| JsonElement value = json.getAsJsonObject().get(VALUE); |
| if (value == null || value.isJsonNull()) { |
| return Optional.empty(); |
| } |
| |
| // handle the situation when one uses Optional without type parameter which is an equivalent of |
| // <?> type |
| ParameterizedType parameterizedType = |
| (ParameterizedType) new TypeLiteral<Optional<?>>() {}.getType(); |
| if (typeOfT instanceof ParameterizedType) { |
| parameterizedType = (ParameterizedType) typeOfT; |
| if (parameterizedType.getActualTypeArguments().length != 1) { |
| throw new JsonParseException("Expected one parameter type in Optional."); |
| } |
| } |
| |
| Type optionalOf = parameterizedType.getActualTypeArguments()[0]; |
| return Optional.of(context.deserialize(value, optionalOf)); |
| } |
| } |