| /** |
| * Licensed to jclouds, Inc. (jclouds) under one or more |
| * contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. jclouds licenses this file |
| * to you 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.jclouds.json.internal; |
| |
| import java.io.IOException; |
| import java.lang.reflect.ParameterizedType; |
| import java.lang.reflect.Type; |
| import java.util.Set; |
| |
| import com.google.common.collect.Sets; |
| import com.google.gson.Gson; |
| import com.google.gson.TypeAdapter; |
| import com.google.gson.TypeAdapterFactory; |
| import com.google.gson.reflect.TypeToken; |
| import com.google.gson.stream.JsonReader; |
| import com.google.gson.stream.JsonWriter; |
| |
| /** |
| * Eliminates null values when deserializing Sets |
| * <p/> |
| * Treats [null] as the empty set; [A, null] as [A]; etc. |
| * |
| * @author Adam Lowe |
| */ |
| public class IgnoreNullSetTypeAdapterFactory implements TypeAdapterFactory { |
| |
| @SuppressWarnings("unchecked") |
| public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) { |
| Type type = typeToken.getType(); |
| if (typeToken.getRawType() != Set.class || !(type instanceof ParameterizedType)) { |
| return null; |
| } |
| |
| Type elementType = ((ParameterizedType) type).getActualTypeArguments()[0]; |
| TypeAdapter<?> elementAdapter = gson.getAdapter(TypeToken.get(elementType)); |
| return (TypeAdapter<T>) newSetAdapter(elementAdapter); |
| } |
| |
| private <E> TypeAdapter<Set<E>> newSetAdapter(final TypeAdapter<E> elementAdapter) { |
| return new TypeAdapter<Set<E>>() { |
| public void write(JsonWriter out, Set<E> value) throws IOException { |
| out.beginArray(); |
| for (E element : value) { |
| elementAdapter.write(out, element); |
| } |
| out.endArray(); |
| } |
| |
| public Set<E> read(JsonReader in) throws IOException { |
| Set<E> result = Sets.newLinkedHashSet(); |
| in.beginArray(); |
| while (in.hasNext()) { |
| E element = elementAdapter.read(in); |
| if (element != null) result.add(element); |
| } |
| in.endArray(); |
| return result; |
| } |
| }.nullSafe(); |
| } |
| } |