com.talvish.tales.serialization.json.translators.JsonArrayToArrayTranslator.java Source code

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Here is the source code for com.talvish.tales.serialization.json.translators.JsonArrayToArrayTranslator.java

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// ***************************************************************************
// *  Copyright 2012 Joseph Molnar
// *
// *  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.talvish.tales.serialization.json.translators;

import java.lang.reflect.Array;

import com.google.common.base.Preconditions;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonNull;
import com.talvish.tales.parts.translators.TranslationException;
import com.talvish.tales.parts.translators.Translator;

/**
 * Translator that converts a json array into a Java array.
 * @author jmolnar
 *
 */
public class JsonArrayToArrayTranslator implements Translator {
    private final Translator elementTranslator;
    private final Class<?> elementType;
    private final boolean readSingles;

    /**
     * Constructor taking the element type and the element translator and
     * there won't be special read handling for non-array single objects.
     * @param theElementType the type of the element
     * @param theElementTranslator the translator to use for elements
     */
    public JsonArrayToArrayTranslator(Class<?> theElementType, Translator theElementTranslator) {
        this(theElementType, theElementTranslator, false);
    }

    /**
     * Constructor taking the element type, the element translator and if 
     * there is special read handling of non-array single objects.
     * @param theElementType the type of the element
     * @param theElementTranslator the translator to use for elements
     * @param readSingles true means that if there is a single object instead of an array in the json it will still be used
     */
    public JsonArrayToArrayTranslator(Class<?> theElementType, Translator theElementTranslator,
            boolean readSingles) {
        Preconditions.checkNotNull(theElementType, "need a type");
        Preconditions.checkNotNull(theElementTranslator, "need a translator");

        elementType = theElementType;
        elementTranslator = theElementTranslator;
        this.readSingles = readSingles;
    }

    /**
     * Translates the received object into an array;
     * If the object is of the wrong type, a TranslationException will occur.
     */
    @Override
    public Object translate(Object anObject) {
        Object returnValue;

        if (anObject == null || anObject.equals(JsonNull.INSTANCE)) {
            returnValue = null;
        } else {
            try {
                // things to look at later
                JsonElement jsonElement = (JsonElement) anObject;
                if (jsonElement.isJsonArray()) {
                    JsonArray jsonArray = (JsonArray) anObject;
                    Object array = Array.newInstance(elementType, jsonArray.size());

                    for (int count = 0; count < jsonArray.size(); count += 1) {
                        Array.set(array, count, elementTranslator.translate(jsonArray.get(count)));
                    }

                    returnValue = array;
                } else if (readSingles) {
                    Object array = Array.newInstance(elementType, 1);
                    Array.set(array, 0, elementTranslator.translate(jsonElement));
                    returnValue = array;
                } else {
                    throw new TranslationException(
                            String.format("Attempt to translate an array but a single object was sent instead."));
                }
            } catch (IllegalArgumentException e) {
                throw new TranslationException(e);
            } catch (ClassCastException e) {
                throw new TranslationException(e);
            }
        }
        return returnValue;
    }
}