com.squareup.wire.WireTypeAdapterFactory.java Source code

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Here is the source code for com.squareup.wire.WireTypeAdapterFactory.java

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/*
 * Copyright 2013 Square 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 com.squareup.wire;

import com.google.gson.Gson;
import com.google.gson.TypeAdapter;
import com.google.gson.TypeAdapterFactory;
import com.google.gson.reflect.TypeToken;
import okio.ByteString;

/**
 * A {@link TypeAdapterFactory} that allows Wire messages to be serialized and deserialized
 * using the GSON Json library. To create a {@link Gson} instance that works with Wire,
 * use the {@link com.google.gson.GsonBuilder} interface:
 *
 * <pre>
 * Wire wire = new Wire(...extension classes...)
 * WireTypeAdapterFactory wireTypeAdapterFactory = new WireTypeAdapterFactory(wire);
 * Gson gson = new GsonBuilder()
 *     .registerTypeAdapterFactory(wireTypeAdapterFactory)
 *     .create();
 * </pre>
 *
 * The resulting {@link Gson} instance will be able to serialize and deserialize any Wire
 * {@link Message} type, including extensions and unknown field values. The JSON encoding is
 * intended to be compatible with the
 * <a href="https://code.google.com/p/protobuf-java-format/">protobuf-java-format</a>
 * library. Note that version 1.2 of that API has a
 * <a href="https://code.google.com/p/protobuf-java-format/issues/detail?id=47">bug</a>
 * in the way it serializes unknown fields, so we use our own approach for this case.
 */
public final class WireTypeAdapterFactory implements TypeAdapterFactory {

    private final Wire wire;

    /**
     * Constructs an adapter that is capable of serializing and deserializing extension values
     * that may have {@code Message} and {@code Enum} values belonging to the given whitelist. A
     * shortened version of the class name will be used as a type marker in the JSON serialized
     * form. It is not necessary to include non-extension classes in the whitelist.
     */
    public WireTypeAdapterFactory(Wire wire) {
        this.wire = wire;
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
        if (type.getRawType().equals(ByteString.class)) {
            return (TypeAdapter<T>) new ByteStringTypeAdapter();
        }
        if (Message.class.isAssignableFrom(type.getRawType())) {
            return (TypeAdapter<T>) new MessageTypeAdapter(wire, gson, type);
        }
        return null;
    }
}