com.economic.persistgson.internal.bind.ObjectTypeAdapter.java Source code

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Here is the source code for com.economic.persistgson.internal.bind.ObjectTypeAdapter.java

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/*
 * Copyright (C) 2011 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 com.economic.persistgson.internal.bind;

import com.economic.persistgson.Gson;
import com.economic.persistgson.JsonElement;
import com.economic.persistgson.JsonParser;
import com.economic.persistgson.TypeAdapterFactory;
import com.economic.persistgson.stream.JsonReader;
import com.economic.persistgson.stream.JsonToken;
import com.economic.persistgson.stream.JsonWriter;
import com.economic.persistgson.TypeAdapter;
import com.economic.persistgson.internal.LinkedTreeMap;
import com.economic.persistgson.reflect.TypeToken;
import com.economic.persistgson.stream.MalformedJsonException;
import com.google.common.math.DoubleMath;

import java.io.IOException;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * Adapts types whose static type is only 'Object'. Uses getClass() on
 * serialization and a primitive/Map/List on deserialization.
 */
public final class ObjectTypeAdapter extends TypeAdapter<Object> {
    public static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
        @SuppressWarnings("unchecked")
        @Override
        public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
            if (type.getRawType() == Object.class) {
                return (TypeAdapter<T>) new ObjectTypeAdapter(gson);
            }
            return null;
        }
    };

    private final Gson gson;
    private final JsonParser jsonParser = new JsonParser();

    ObjectTypeAdapter(Gson gson) {
        this.gson = gson;
    }

    @Override
    public Object read(JsonReader in) throws IOException {
        JsonToken token = in.peek();
        switch (token) {
        case BEGIN_ARRAY:
            List<Object> list = new ArrayList<Object>();
            in.beginArray();
            while (in.hasNext()) {
                list.add(read(in));
            }
            in.endArray();
            return list;

        case BEGIN_OBJECT:
            Map<String, Object> map = new LinkedTreeMap<String, Object>();
            in.beginObject();
            while (in.hasNext()) {
                map.put(in.nextName(), read(in));
            }
            in.endObject();
            return map;

        case STRING:
            return in.nextString();

        case NUMBER:
            JsonElement element = jsonParser.parse(in);
            String elementString = element.getAsString();
            double asDouble = Double.parseDouble(elementString); // don't catch this NumberFormatException.
            if ((Double.isNaN(asDouble) || Double.isInfinite(asDouble))) {
                throw new com.economic.persistgson.stream.MalformedJsonException(
                        "JSON forbids NaN and infinities: " + asDouble);
            }
            if (DoubleMath.isMathematicalInteger(asDouble)) {
                return (long) asDouble;
            } else {
                return asDouble;
            }
        case BOOLEAN:
            return in.nextBoolean();

        case NULL:
            in.nextNull();
            return null;

        default:
            throw new IllegalStateException();
        }
    }

    @SuppressWarnings("unchecked")
    @Override
    public void write(JsonWriter out, Object value) throws IOException {
        if (value == null) {
            out.nullValue();
            return;
        }

        TypeAdapter<Object> typeAdapter = (TypeAdapter<Object>) gson.getAdapter(value.getClass());
        if (typeAdapter instanceof ObjectTypeAdapter) {
            out.beginObject();
            out.endObject();
            return;
        }

        typeAdapter.write(out, value);
    }
}