br.gov.frameworkdemoiselle.internal.implementation.StrategySelector.java Source code

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/*
 * Demoiselle Framework
 * Copyright (C) 2010 SERPRO
 * ----------------------------------------------------------------------------
 * This file is part of Demoiselle Framework.
 * 
 * Demoiselle Framework is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License version 3
 * as published by the Free Software Foundation.
 * 
 * This program 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 Lesser General Public License version 3
 * along with this program; if not,  see <http://www.gnu.org/licenses/>
 * or write to the Free Software Foundation, Inc., 51 Franklin Street,
 * Fifth Floor, Boston, MA  02110-1301, USA.
 * ----------------------------------------------------------------------------
 * Este arquivo  parte do Framework Demoiselle.
 * 
 * O Framework Demoiselle  um software livre; voc pode redistribu-lo e/ou
 * modific-lo dentro dos termos da GNU LGPL verso 3 como publicada pela Fundao
 * do Software Livre (FSF).
 * 
 * Este programa  distribudo na esperana que possa ser til, mas SEM NENHUMA
 * GARANTIA; sem uma garantia implcita de ADEQUAO a qualquer MERCADO ou
 * APLICAO EM PARTICULAR. Veja a Licena Pblica Geral GNU/LGPL em portugus
 * para maiores detalhes.
 * 
 * Voc deve ter recebido uma cpia da GNU LGPL verso 3, sob o ttulo
 * "LICENCA.txt", junto com esse programa. Se no, acesse <http://www.gnu.org/licenses/>
 * ou escreva para a Fundao do Software Livre (FSF) Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA 02111-1301, USA.
 */
package br.gov.frameworkdemoiselle.internal.implementation;

import static br.gov.frameworkdemoiselle.annotation.Priority.MIN_PRIORITY;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import br.gov.frameworkdemoiselle.annotation.Priority;
import br.gov.frameworkdemoiselle.configuration.ConfigurationException;
import br.gov.frameworkdemoiselle.internal.producer.ResourceBundleProducer;
import br.gov.frameworkdemoiselle.util.ResourceBundle;

public final class StrategySelector implements Serializable {

    public static final int CORE_PRIORITY = MIN_PRIORITY;

    public static final int EXTENSIONS_L1_PRIORITY = CORE_PRIORITY - 100;

    public static final int EXTENSIONS_L2_PRIORITY = EXTENSIONS_L1_PRIORITY - 100;

    public static final int COMPONENTS_PRIORITY = EXTENSIONS_L2_PRIORITY - 100;

    private static final long serialVersionUID = 1L;

    private static ResourceBundle bundle;

    private StrategySelector() {
    }

    private static ResourceBundle getBundle() {
        if (bundle == null) {
            bundle = ResourceBundleProducer.create("demoiselle-core-bundle");
        }

        return bundle;
    }

    public static <T> Class<? extends T> getClass(Class<T> type, List<Class<? extends T>> options)
            throws ConfigurationException {
        Class<? extends T> selected = null;

        for (Class<? extends T> option : options) {
            if (selected == null || getPriority(option) < getPriority(selected)) {
                selected = option;
            }
        }

        checkForAmbiguity(type, selected, options);

        return selected;
    }

    private static <T> void checkForAmbiguity(Class<T> type, Class<? extends T> selected,
            List<Class<? extends T>> options) throws ConfigurationException {
        int selectedPriority = getPriority(selected);

        List<Class<? extends T>> ambiguous = new ArrayList<Class<? extends T>>();

        for (Class<? extends T> option : options) {
            if (selected != option && selectedPriority == getPriority(option)) {
                ambiguous.add(option);
            }
        }

        if (!ambiguous.isEmpty()) {
            ambiguous.add(selected);

            String message = getExceptionMessage(type, ambiguous);
            throw new ConfigurationException(message);
        }
    }

    private static <T> String getExceptionMessage(Class<T> type, List<Class<? extends T>> ambiguous) {
        StringBuffer classes = new StringBuffer();

        int i = 0;
        for (Class<? extends T> clazz : ambiguous) {
            if (i++ != 0) {
                classes.append(", ");
            }

            classes.append(clazz.getCanonicalName());
        }

        return getBundle().getString("ambiguous-strategy-resolution", type.getCanonicalName(), classes.toString());
    }

    private static <T> int getPriority(Class<T> type) {
        int result = Priority.MAX_PRIORITY;
        Priority priority = type.getAnnotation(Priority.class);

        if (priority != null) {
            result = priority.value();
        }

        return result;
    }

    // public static <T> T getExplicitReference(String configKey, Class<T> strategyType, Class<T> defaultType) {
    // Class<T> selectedType = loadSelected(configKey, strategyType, defaultType);
    // return Beans.getReference(selectedType);
    // }
    //
    // @SuppressWarnings("unchecked")
    // private static <T> Class<T> loadSelected(String configKey, Class<T> strategyType, Class<T> defaultType) {
    // ResourceBundle bundle = ResourceBundleProducer.create("demoiselle-core-bundle",
    // Beans.getReference(Locale.class));
    // Class<T> result = null;
    // String canonicalName = null;
    // String typeName = strategyType.getSimpleName().toLowerCase();
    // String key = null;
    // try {
    // URL url = ConfigurationLoader.getResourceAsURL("demoiselle.properties");
    // Configuration config = new PropertiesConfiguration(url);
    // canonicalName = config.getString(configKey, defaultType.getCanonicalName());
    // ClassLoader classLoader = ConfigurationLoader.getClassLoaderForClass(canonicalName);
    // if (classLoader == null) {
    // classLoader = Thread.currentThread().getContextClassLoader();
    // }
    // result = (Class<T>) Class.forName(canonicalName, false, classLoader);
    // result.asSubclass(strategyType);
    // } catch (org.apache.commons.configuration.ConfigurationException cause) {
    // throw new ConfigurationException(bundle.getString("file-not-found", "demoiselle.properties"));
    // } catch (ClassNotFoundException cause) {
    // key = Strings.getString("{0}-class-not-found", typeName);
    // throw new ConfigurationException(bundle.getString(key, canonicalName));
    // } catch (FileNotFoundException e) {
    // throw new ConfigurationException(bundle.getString("file-not-found", "demoiselle.properties"));
    // } catch (ClassCastException cause) {
    // key = Strings.getString("{0}-class-must-be-of-type", typeName);
    // throw new ConfigurationException(bundle.getString(key, canonicalName, strategyType));
    // }
    // return result;
    // }
}