extscript-root-1.0.4/extscript-core-root/extscript-core/src/main/java/org/apache/myfaces/extensions/scripting/core/reloading/SimpleReloadingStrategy.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.myfaces.extensions.scripting.core.reloading;

import org.apache.myfaces.extensions.scripting.core.api.ReloadingStrategy;
import org.apache.myfaces.extensions.scripting.core.api.WeavingContext;

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

/**
 * A simple implementation of our reloading strategy
 * pattern this is the most basic implementation
 * covering our reloading.
 * <p/>
 * Applicable for most artifacts except for now managed beans
 * <p/> *
 *
 * @author Werner Punz (latest modification by $Author$)
 * @version $Revision$ $Date$
 */

public class SimpleReloadingStrategy implements ReloadingStrategy
{



    public SimpleReloadingStrategy() {

    }

    /**
     * <p>
     * the central callback for our strategy here
     * it has to handle the reload of the scriptingInstance
     * if possible, otherwise it has to return the
     * original object if no reload was necessary or possible
     * </p>
     *
     * @param scriptingInstance the instance to be reloaded by the system
     * @return either the same object or a new instance utilizing the changed code
     */
    public Object reload(Object scriptingInstance, int engineType, int artifactType) {
       //reload the class to get new static content if needed
        Class aclass = WeavingContext.getInstance().reload(scriptingInstance.getClass());

        if (aclass == null || aclass.hashCode() == scriptingInstance.getClass().hashCode()) {
            //class of this object has not changed although
            // reload is enabled we can skip the rest now
            return scriptingInstance;
        }
        getLog().info("[EXT-SCRIPTING] possible reload for " + scriptingInstance.getClass().getName());
        /*only recreation of empty constructor classes is possible*/
        try {
            //reload the object by instantiating a new class and
            // assigning the attributes properly
            Object newObject = aclass.newInstance();

            /*now we shuffle the properties between the objects*/
            mapProperties(newObject, engineType, scriptingInstance);

            return newObject;
        } catch (Exception e) {
            getLog().log(Level.SEVERE, "reload ", e);
        }
        return null;

    }

    /**
     * helper to map the properties wherever possible
     * <p/>
     * This is the simplest solution for now,
     * we apply only a copy properties here, which should be enough
     * for all artifacts except the managed beans and the ones
     * which have to preserve some kind of delegate before instantiation.
     *
     * @param target the target which has to receive the properties
     * @param src    the source which has the original properties
     */
    protected void mapProperties(Object target, int engineType, Object src) {
       WeavingContext.getInstance().getEngine(engineType).copyProperties(target, src);
    }

    protected Logger getLog() {
        return Logger.getLogger(this.getClass().getName());
    }

}