optimizedstatemanager.java

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/*
 * Copyright 2002-2004 the original author or authors.
 *
 * Licensed 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 de.mindmatters.faces.application;

import javax.faces.FactoryFinder;
import javax.faces.application.StateManager;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
import javax.faces.render.RenderKit;
import javax.faces.render.RenderKitFactory;
import javax.faces.render.ResponseStateManager;

import org.springframework.util.Assert;

/**
 * <strong>OptimizedStateManager</strong> saves and restores the state of the
 * component tree.
 * 
 * @author Andreas Kuhrwahl
 * 
 */
public final class OptimizedStateManager extends
        AbstractViewBuildingStateManager {

    /**
     * Creates an OptimizedStateManager with the given state manager
     * <code>delegate</code> of the underlying JSF implementation.
     * 
     * @param delegate
     *            the original state manager of the underlying JSF
     *            implementation
     */
    public OptimizedStateManager(final StateManager delegate) {
        super(delegate);
    }

    /**
     * {@inheritDoc}
     */
    protected Object getComponentStateToSave(final FacesContext context) {
        UIViewRoot viewRoot = context.getViewRoot();
        return viewRoot.processSaveState(context);
    }

    /**
     * {@inheritDoc}
     */
    protected void restoreComponentState(final FacesContext context,
            final UIViewRoot viewRoot, final String renderKitId) {
        Object state = getResponseStateManager(context, renderKitId)
                .getComponentStateToRestore(context);
        Assert.notNull(state);
        viewRoot.processRestoreState(context, state);
    }

    /**
     * Resolves the appropriate ResponseStateManager for the given
     * <code>renderKitId</code>.
     * 
     * @param context
     *            {@link FacesContext} for the current request
     * @param renderKitId
     *            the renderKitId used to render this response. Must not be
     *            <code>null</code>.
     * @return the ResponseStateManager to use
     * @throws javax.faces.FacesException
     *             in cases of errors
     */
    private ResponseStateManager getResponseStateManager(
            final FacesContext context, final String renderKitId) {
        RenderKit renderKit = ((RenderKitFactory) FactoryFinder
                .getFactory(FactoryFinder.RENDER_KIT_FACTORY)).getRenderKit(
                context, renderKitId);
        Assert.notNull(renderKit);
        return renderKit.getResponseStateManager();
    }

}