extendedfaceletviewhandler.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 java.io.IOException;

import javax.faces.application.ViewHandler;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;

import com.sun.facelets.FaceletViewHandler;

/**
 * Extends {@link FaceletViewHandler} to implement
 * {@link ViewBuilder#buildView(FacesContext, String)}.
 * 
 * <p>
 * <strong>Should never used directly within a faces-config file. Will be
 * instantiated by the {@link FaceletViewBuilder} class via reflection.</strong>
 * </p>
 * 
 * @author Andreas Kuhrwahl
 */
public class ExtendedFaceletViewHandler extends FaceletViewHandler {

    /** Already Initialized? */
    private Object isInitialized;

    /**
     * Default constructor. <strong>Must</strong> be invoked by subclasses.
     * 
     * @param viewHandler
     *            the original ViewHandler of the underlying JSF implementation.
     */
    public ExtendedFaceletViewHandler(final ViewHandler viewHandler) {
        super(viewHandler);
    }

    /**
     * {@inheritDoc}
     */
    protected void initialize(final FacesContext context) {
        synchronized (this) {
            if (this.isInitialized == null) {
                this.isInitialized = new Object();
                super.initialize(context);
            }
        }
    }

    /**
     * {@inheritDoc}
     */
    protected final String getRenderedViewId(final FacesContext context,
            final String actionId) {
        return actionId;
    }

    /**
     * Builds the view.
     * 
     * @param context
     *            {@link FacesContext} for the current request
     * @param viewId
     *            the view identifier for the current request
     * @return the created {@link UIViewRoot}
     * @throws javax.faces.FacesException
     *             if a servlet error occurs
     * @throws IOException
     *             if an input/output error occurs
     */
    public final UIViewRoot buildView(final FacesContext context,
            final String viewId) throws IOException {
        if (this.isInitialized == null) {
            this.initialize(context);
        }
        UIViewRoot viewRoot = createView(context, viewId);
        context.setViewRoot(viewRoot);
        super.buildView(context, viewRoot);
        return viewRoot;
    }

    /**
     * {@inheritDoc}
     */
    protected final void buildView(final FacesContext context,
            final UIViewRoot viewToRender) throws IOException {
        if (viewToRender.getChildren().isEmpty()) {
            super.buildView(context, viewToRender);
        }
    }

}