net.bpiwowar.experimaestro.tasks.ClassChooserAdapter.java Source code

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Here is the source code for net.bpiwowar.experimaestro.tasks.ClassChooserAdapter.java

Source

package net.bpiwowar.experimaestro.tasks;

/*
 * This file is part of experimaestro.
 * Copyright (c) 2014 B. Piwowarski <benjamin@bpiwowar.net>
 *
 * experimaestro is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * experimaestro is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with experimaestro.  If not, see <http://www.gnu.org/licenses/>.
 */

import com.google.gson.*;
import com.google.gson.internal.bind.JsonTreeReader;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;
import com.google.gson.stream.JsonWriter;

import java.io.IOException;
import java.util.HashMap;

/**
 * Generic object deserialization
 */
public class ClassChooserAdapter extends ReaderTypeAdapter {
    private final Gson gson;
    private HashMap<Object, Class<?>> types = new HashMap<>();

    public ClassChooserAdapter(Gson gson, ClassChooser annotation) {
        this.gson = gson;
        // Using instances
        for (Class<?> aClass : annotation.classes())
            if (!addClass(aClass)) {
                throw new RuntimeException("A provided instance is not a valid choice (" + aClass + " for )");
            }

        for (ClassChooserInstance instance : annotation.instances()) {
            types.put(instance.name(), instance.instance());
        }

        // Using packages
        for (Class<?> zclass : annotation.classesOfPackage()) {
            Introspection.getClasses(aClass -> {
                addClass(aClass);
                return false;
            }, zclass.getPackage().getName(), 0);
        }

        if (types.isEmpty())
            throw new RuntimeException("No class provided");
    }

    private boolean addClass(Class<?> aClass) {
        final ClassChooserInstance annotation = aClass.getAnnotation(ClassChooserInstance.class);
        types.put(annotation.name(), aClass);
        return false;
    }

    @Override
    public Object read(JsonReader in) throws IOException {
        // If string, use this
        if (in.peek() == JsonToken.STRING) {
            final String type = in.nextString();
            final Class<?> aClass = types.get(type);
            if (aClass == null) {
                throw new JsonParseException("No type " + type + " defined");
            }
            return gson.fromJson(new JsonObject(), aClass);
        }

        // Get the Json object
        final JsonObject json;
        if (in instanceof JsonTreeReader) {
            json = ((JsonTreeReader) in).getJsonObject();
        } else {
            json = new JsonParser().parse(in).getAsJsonObject();
        }

        // Get the type
        final JsonElement _type = json.get("type");
        if (_type == null) {
            throw new JsonParseException("No type defined");
        }
        String type = _type.getAsString();

        // Get the class of the object to create
        final Class<?> aClass = types.get(type);
        if (aClass == null) {
            throw new JsonParseException("No type " + type + " defined");
        }

        return gson.fromJson(json, aClass);
    }
}