jakarta.faces.component.StateHolderSaver Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jakarta.faces Show documentation
EE4J Compatible Implementation for Jakarta Faces API
The newest version!
/*
 * Copyright (c) 1997, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package jakarta.faces.component;

import java.io.Serializable;
import java.lang.reflect.InvocationTargetException;

import jakarta.faces.context.FacesContext;

/**
 * 
 * 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 static final String DYNAMIC_COMPONENT = "com.sun.faces.DynamicComponent";

    private enum StateHolderTupleIndices {
        StateHolderSaverInstance, ComponentAddedDynamically, LastMember
    }

    public boolean componentAddedDynamically() {
        boolean result = false;

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

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

        // else the object to save did implement StateHolder

        if (null != savedState) {
            // don't need to check transient, since that was done on
            // the saving side.
            Serializable[] tuple = (Serializable[]) savedState;
            result = (Boolean) tuple[StateHolderTupleIndices.ComponentAddedDynamically.ordinal()];
        }

        return result;
    }

    public StateHolderSaver(FacesContext context, Object toSave) {
        if (toSave == null) {
            className = null;
        } else {
            className = toSave.getClass().getName();
        }

        if (toSave instanceof StateHolder) {
            // do not save an attached object that is marked transient.
            if (!((StateHolder) toSave).isTransient()) {
                Serializable[] tuple = new Serializable[StateHolderTupleIndices.LastMember.ordinal()];

                tuple[StateHolderTupleIndices.StateHolderSaverInstance.ordinal()] = (Serializable) ((StateHolder) toSave).saveState(context);
                if (toSave instanceof UIComponent) {
                    tuple[StateHolderTupleIndices.ComponentAddedDynamically.ordinal()] = ((UIComponent) toSave).getAttributes().containsKey(DYNAMIC_COMPONENT)
                            ? Boolean.TRUE
                            : Boolean.FALSE;
                }
                savedState = tuple;
            } 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 {
        // 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
        final Object result;
        final Class toRestoreClass;

        try {
            toRestoreClass = loadClass(className, this);
        } catch (ClassNotFoundException e) {
            throw new IllegalStateException(e);
        }

        try {
            result = toRestoreClass.getDeclaredConstructor().newInstance();
        } catch (InstantiationException | IllegalAccessException | NoSuchMethodException | InvocationTargetException e) {
            throw new IllegalStateException(e);
        }

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