AbstractRegistry.java

/**
 * Copyright (C) 2011-2015 The XDocReport Team <xdocreport@googlegroups.com>
 *
 * All rights reserved.
 *
 * Permission is hereby granted, free  of charge, to any person obtaining
 * a  copy  of this  software  and  associated  documentation files  (the
 * "Software"), to  deal in  the Software without  restriction, including
 * without limitation  the rights to  use, copy, modify,  merge, publish,
 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
 * permit persons to whom the Software  is furnished to do so, subject to
 * the following conditions:
 *
 * The  above  copyright  notice  and  this permission  notice  shall  be
 * included in all copies or substantial portions of the Software.
 *
 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package fr.opensagres.xdocreport.core.registry;

import java.util.Iterator;
import java.util.logging.Level;
import java.util.logging.Logger;

import fr.opensagres.xdocreport.core.discovery.IBaseDiscovery;
import fr.opensagres.xdocreport.core.internal.JDKServiceLoader;
import fr.opensagres.xdocreport.core.logging.LogUtils;

public abstract class AbstractRegistry<Discovery extends IBaseDiscovery>
{

    /**
     * Logger for this class
     */
    private static final Logger LOGGER = LogUtils.getLogger( AbstractRegistry.class.getName() );

    private boolean initialized;

    private final Class<Discovery> registryType;

    public AbstractRegistry( Class<Discovery> registryType )
    {
        this.registryType = registryType;
    }

    public void initialize()
    {
        initializeIfNeeded();
    }

    protected void initializeIfNeeded()
    {
        if ( !initialized )
        {
            onStartInitialization();
            // getClass().getClassLoader() to work under OSGi context

            Iterator<Discovery> discoveries =
                JDKServiceLoader.lookupProviders( registryType, getClass().getClassLoader() );
            if ( LOGGER.isLoggable( Level.FINE ) )
            {
                LOGGER.fine( "discoveries found ? " + discoveries.hasNext() );
            }

            while ( discoveries.hasNext() )
            {
                Discovery instance = discoveries.next();
                try
                {
                    boolean result = registerInstance( instance );
                    if ( LOGGER.isLoggable( Level.FINE ) )
                    {
                        LOGGER.fine( "Registered Discovery instance  " + instance + " " + result );
                    }
                }
                catch ( Throwable e )
                {
                    LOGGER.log( Level.WARNING, "Error while registration of Discovery instance  " + instance, e );
                }
            }
            onEndInitialization();
            initialized = true;
        }
    }

    /**
     * Method called when registry start initialization.
     */
    protected void onStartInitialization()
    {

    }

    /**
     * Method called when registry end initialization.
     */
    protected void onEndInitialization()
    {

    }

    /**
     * Register the instance in the registry.
     * 
     * @param instance
     * @return true if instance cannot be registered and false otherwise.
     */
    protected abstract boolean registerInstance( Discovery instance );

    /**
     * Dispose the registry.
     */
    public final void dispose()
    {
        doDispose();
        this.initialized = false;
    }

    protected abstract void doDispose();
}