ClassTransform.java

/*
 * ====================
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2008-2009 Sun Microsystems, Inc. All rights reserved.
 *
 * The contents of this file are subject to the terms of the Common Development
 * and Distribution License("CDDL") (the "License").  You may not use this file
 * except in compliance with the License.
 *
 * You can obtain a copy of the License at
 * http://opensource.org/licenses/cddl1.php
 * See the License for the specific language governing permissions and limitations
 * under the License.
 *
 * When distributing the Covered Code, include this CDDL Header Notice in each file
 * and include the License file at http://opensource.org/licenses/cddl1.php.
 * If applicable, add the following below this CDDL Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyrighted [year] [name of copyright owner]"
 * ====================
 */
package org.identityconnectors.patternparser;

import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.Map;

import org.w3c.dom.Element;

/**
 * A ClassTransform specifies a Class with a constructor taking a single
 * argument of the type to which the transform is applied (determined at
 * run-time).
 * <p>
 * Represented in XML by
 *
 * <pre>
 * <ClassTransform transform='<b>className</b>'/>
 * </pre>
 */

public class ClassTransform extends Transform<Object> {
    private static final String TRANSFORM = "transform";
    private Class<? extends Object> clazz;
    private transient Map<Class<? extends Object>, Constructor<?>> classConstructorMap;

    protected String getAttributes() {
        return super.getAttributes() + attributeToString(TRANSFORM, clazz.getName());
    }

    /**
     * Create a ClassTransform from an Element.
     *
     * @param element
     * @throws ClassNotFoundException
     *             if the class cannot be located
     */
    public ClassTransform(Element element) throws ClassNotFoundException {
        this(Class.forName(element.getAttribute(TRANSFORM)));
    }

    /**
     * Create a ClassTransform from an Element.
     *
     * @param clazz
     *            the Class to instantiate as part of the transform
     */
    public ClassTransform(Class<? extends Object> clazz) {
        classConstructorMap = new HashMap<Class<? extends Object>, Constructor<?>>();
        this.clazz = clazz;
    }

    /**
     * Create a new object by executing
     *
     * <pre>
     * <b>transform</b>.getConstructor(<b>input</b>.getClass()).newInstance(<b>input</b>)
     * </pre>
     *
     * .
     *
     * @param input
     *            the object to be transformed
     * @return an instance of Class <b>transform</b>
     */
    @Override
    public Object transform(Object input) throws Exception {
        Class<? extends Object> inputClass = input.getClass();
        if (!classConstructorMap.containsKey(inputClass)) {
            classConstructorMap.put(inputClass, this.clazz.getConstructor(inputClass));
        }
        return classConstructorMap.get(inputClass).newInstance(input);
    }
}