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 *   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
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package org.apache.cayenne.remote.hessian;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.map.EntityResolver;
import org.apache.cayenne.util.Util;

import com.caucho.hessian.io.AbstractSerializerFactory;
import com.caucho.hessian.io.SerializerFactory;

/**
 * A utility class that configures Hessian serialization properties using reflection.
 * 
 * @since 1.2
 */
public class HessianConfig {

    /**
     * Creates a Hessian SerializerFactory configured with zero or more
     * AbstractSerializerFactory extensions. Extensions are specified as class names. This
     * method can inject EntityResolver if an extension factory class defines
     * <em>setEntityResolver(EntityResolver)</em> method.
     * 
     * @param factoryNames an array of factory class names. Each class must be a concrete
     *            subclass of <em>com.caucho.hessian.io.AbstractSerializerFactory</em>
     *            and have a default constructor.
     * @param resolver if not null, EntityResolver will be injected into all factories
     *            that implement <em>setEntityResolver(EntityResolver)</em> method.
     */
    public static SerializerFactory createFactory(
            String[] factoryNames,
            EntityResolver resolver) {

        SerializerFactory factory = new CayenneSerializerFactory();

        if (factoryNames != null && factoryNames.length > 0) {

            for (String factoryName : factoryNames) {

                try {
                    factory.addFactory(loadFactory(factoryName, resolver));
                }
                catch (Exception e) {
                    throw new CayenneRuntimeException("Error configuring factory class "
                            + factoryName, e);
                }
            }
        }

        return factory;
    }

    static AbstractSerializerFactory loadFactory(
            String factoryName,
            EntityResolver resolver) throws Exception {

        ClassLoader loader = Thread.currentThread().getContextClassLoader();
        Class factoryClass = Class.forName(factoryName, true, loader);

        if (!AbstractSerializerFactory.class.isAssignableFrom(factoryClass)) {
            throw new IllegalArgumentException(factoryClass
                    + " is not a AbstractSerializerFactory");
        }

        Constructor c = factoryClass.getDeclaredConstructor();
        if (!Util.isAccessible(c)) {
            c.setAccessible(true);
        }

        AbstractSerializerFactory object = (AbstractSerializerFactory) c.newInstance();

        if (resolver != null) {
            try {

                Method setter = factoryClass.getDeclaredMethod(
                        "setEntityResolver",
                        EntityResolver.class);

                if (!Util.isAccessible(setter)) {
                    setter.setAccessible(true);
                }

                setter.invoke(object, resolver);
            }
            catch (Exception e) {
                // ignore injection exception
            }
        }

        return object;
    }

}