src/java/org/apache/turbine/util/template/TemplateScreen.java

package org.apache.turbine.util.template;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Turbine" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache Turbine", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.ecs.ConcreteElement;

import org.apache.turbine.modules.ScreenLoader;
import org.apache.turbine.util.RunData;

/**
 * Returns output of a Screen module.  An instance of this is
 * placed in the Velocity context by the VelocityDirectLayout.  This
 * allows the screen to be executed only at rendering.
 * Here's how it's used in a template:
 *
 * <p>
 * <code>
 * $screen_placeholder
 * </code>
 * <p>
 * <code>
 * $screen_placeholder.setScreen("Test")
 * </code>
 * </p>
 *
 * @author <a href="raphael@apache.org">Raphaël Luta</a>
 * @version $Id$
 */
public class TemplateScreen
{
    /** Logging */
    private static Log log = LogFactory.getLog(TemplateScreen.class);

    /* The RunData object. */
    private RunData data;

    /* The name of the screen template. */
    private String screen;

    /**
     * Constructor
     *
     * @param data A Turbine RunData object.
     */
    public TemplateScreen(RunData data)
    {
        this.data = data;
        this.screen = data.getScreen();
    }

    /**
     * Set the screen.
     *
     * @param screen A String with the name of the screen module
     * @return A TemplateScreen (self).
     */
    public TemplateScreen setScreen(String screen)
    {
        this.screen = screen;
        return this;
    }

    /**
     * Builds the output of the navigation template.
     *
     * @return A String.
     */
    public String toString()
    {
        String returnValue = "";

        try
        {
            ConcreteElement results = ScreenLoader.getInstance()
                    .eval(data, this.screen);

            if (results != null)
            {
                returnValue = results.toString();
            }
        }
        catch (Exception e)
        {
            log.error(e);
        }

        return returnValue;
    }
}