proposals/henning/jsp-tags/src/java/org/apache/turbine/services/jsp/tags/TemplateLinkTag.java

package org.apache.turbine.services.jsp.tags;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 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,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * 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 java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.TagSupport;
import org.apache.turbine.services.jsp.JspService;
import org.apache.turbine.util.DynamicURI;
import org.apache.turbine.util.Log;
import org.apache.turbine.util.RunData;
import org.apache.turbine.util.template.TemplateLink;

/**
  * Supporting class for the TemplateLink tag.
  * Uses the TemplateLink class to construct a URI
  *
  * @author <a href="mailto:ingo@raleigh.ibm.com">Ingo Schuster</a>
  */
public class TemplateLinkTag extends TagSupport
{
     /**
      * template parameter defines the template to set
      * mandatory parameter
      */
     private String template;

     /**
      * The setter for template parameter
      */
     public void setTemplate(String template)
     {
         this.template = template;
     }

     /**
      * action parameter defines the action to set
      * optional parameter
      */
     private String action;

     /**
      * The setter for screen parameter
      */
     public void setAction(String action)
     {
         this.action = action;
     }

     public int doStartTag() throws JspException
     {
         RunData data = 
             (RunData)pageContext.getAttribute(JspService.RUNDATA, 
                                               PageContext.REQUEST_SCOPE);

         TemplateLink link = new TemplateLink( data );
         DynamicURI uri = link.setPage( template );
         if ( action != null ) uri = uri.setAction( action );

         try
         {
             if (uri != null) {
                 pageContext.getOut().print(uri.toString());
             }
         }
         catch (Exception e)
         {
             String message = 
                 "Error processing TemplateLink-tag, parameter: template='"
                 + template + "', action='" +action +"'";
             Log.error(message, e);
             try
             {
                 data.getOut().print( message );
             }
             catch(java.io.IOException ioe) {}
         }

         return EVAL_BODY_INCLUDE;
     }

}