ConverterFactory.java

/**
 * Copyright (c) 2010-2016 by the respective copyright holders.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.openhab.binding.homematic.internal.converter;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.openhab.binding.homematic.internal.config.binding.HomematicBindingConfig;
import org.openhab.binding.homematic.internal.config.binding.ValueBindingConfig;
import org.openhab.binding.homematic.internal.converter.state.Converter;
import org.openhab.core.items.Item;
import org.openhab.core.types.State;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A factory for creating converters which translates between Homematic values
 * and openHAB States/Commands.
 *
 * @author Gerhard Riegler
 * @since 1.5.0
 */
public class ConverterFactory {
    private static final Logger logger = LoggerFactory.getLogger(ConverterFactory.class);

    public static final String CONVERTER_PACKAGE = "org.openhab.binding.homematic.internal.converter.state.";

    private TypeComparator typeComparator = new TypeComparator();
    private Map<String, Converter<?>> converterCache = new HashMap<String, Converter<?>>();

    /**
     * Returns the converter for an item or a custom converter if specified in
     * the binding.
     */
    public Converter<? extends State> createConverter(Item item, HomematicBindingConfig bindingConfig) {
        if (bindingConfig != null && bindingConfig instanceof ValueBindingConfig
                && ((ValueBindingConfig) bindingConfig).getConverter() != null) {
            logger.debug("Using custom converter for {}", bindingConfig);
            return ((ValueBindingConfig) bindingConfig).getConverter();
        }

        List<Class<? extends State>> acceptedTypes = new ArrayList<Class<? extends State>>(item.getAcceptedDataTypes());
        Collections.sort(acceptedTypes, typeComparator);

        for (Class<? extends State> clazz : acceptedTypes) {
            String converterName = clazz.getSimpleName() + "Converter";

            Converter<?> converter = converterCache.get(converterName);
            if (converter == null) {
                try {
                    converter = (Converter<?>) Class.forName(CONVERTER_PACKAGE + converterName).newInstance();
                    converterCache.put(converterName, converter);
                } catch (Exception e) {
                    // ignore
                }
            }

            if (converter != null) {
                return converter;
            }
        }
        logger.warn("Can't find converter for {}, value is not published!", bindingConfig);
        return null;
    }

}