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This is the master POM file for Oracle's Implementation of the JSF 2.1 Specification.
There is a newer version: 2.1
/*
 * $Id: StateHolderSaver.java,v 1.16.4.1 2008/12/08 18:07:13 rlubke Exp $
 */

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
 * 
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
 * Sun designates this particular file as subject to the "Classpath" exception
 * as provided by Sun in the GPL Version 2 section of the License file that
 * accompanied this code.  If applicable, add the following below the License
 * Header, with the fields enclosed by brackets [] replaced by your own
 * identifying information: "Portions Copyrighted [year]
 * [name of copyright owner]"
 * 
 * Contributor(s):
 * 
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package javax.faces.component;

import javax.faces.context.FacesContext;

import java.io.Serializable;

/**
 * Helper class for saving and restoring attached objects.
 */
class StateHolderSaver implements Serializable {

    private static final long serialVersionUID = 6470180891722042701L;

    private String className = null;
    private Serializable savedState = null;

    public StateHolderSaver(FacesContext context, Object toSave) {
	className = toSave.getClass().getName();
	
        if (toSave instanceof StateHolder) {
            // do not save an attached object that is marked transient.
            if (!((StateHolder)toSave).isTransient()) {
                savedState = (Serializable) ((StateHolder)toSave).saveState(context);
            } else {
                className = null;
            }
        }
	else if (toSave instanceof Serializable) {
	    savedState = (Serializable) toSave;
	    className = null;
	}
    }

    /**
     *
     * @return the restored {@link StateHolder} instance.
     */

    public Object restore(FacesContext context) throws IllegalStateException {
        Object result = null;
        Class toRestoreClass;

	// if the Object to save implemented Serializable but not
	// StateHolder
	if (null == className && null != savedState) {
	    return savedState;
	}

	// if the Object to save did not implement Serializable or
	// StateHolder
        if ( className == null) {
            return null;
        }

	// else the object to save did implement StateHolder
        
        try {
            toRestoreClass = loadClass(className, this);
        }
        catch (ClassNotFoundException e) {
	    throw new IllegalStateException(e);
        }

        if (null != toRestoreClass) {
            try {
                result = toRestoreClass.newInstance();
            }
            catch (InstantiationException e) {
                throw new IllegalStateException(e);
            }
            catch (IllegalAccessException a) {
                throw new IllegalStateException(a);
            }
        }

        if (null != result && null != savedState &&
	    result instanceof StateHolder) {
	    // don't need to check transient, since that was done on
	    // the saving side.
	    ((StateHolder)result).restoreState(context, savedState);
        }
        return result;
    }


    private static Class loadClass(String name, 
            Object fallbackClass) throws ClassNotFoundException {
        ClassLoader loader =
            Thread.currentThread().getContextClassLoader();
        if (loader == null) {
            loader = fallbackClass.getClass().getClassLoader();
        }
        return Class.forName(name, false, loader);
    }
}