/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2000-2003 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://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", "Tapestry"
* 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"
* or "Tapestry", nor may "Apache" or "Tapestry" 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 TAPESTRY CONTRIBUTOR COMMUNITY
* 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/>.
*
*/
package org.apache.tapestry.jsp;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
import ognl.ClassResolver;
import ognl.DefaultClassResolver;
import org.apache.tapestry.Tapestry;
import org.apache.tapestry.link.DirectLink;
import org.apache.tapestry.parse.TemplateParser;
import org.apache.tapestry.util.prop.OgnlUtils;
/**
* Contains common code and methods for all the Tapestry JSP tag implementations.
*
* @author Howard Lewis Ship
* @version $Id: AbstractTapestryTag.java,v 1.4 2003/05/28 13:41:41 hlship Exp $
* @since 3.0
*
**/
public abstract class AbstractTapestryTag extends TagSupport
{
private String _servlet = "/app";
public String getServlet()
{
return _servlet;
}
public void setServlet(String servlet)
{
_servlet = servlet;
}
/**
* Implemented in subclasses to provide a
* {@link org.apache.tapestry.jsp.URLRetriever} instance that
* can insert the correct URL into the output.
*
**/
protected abstract URLRetriever getURLRetriever() throws JspException;
/**
* Builds an object array appropriate for use as the service parameters
* for the external service. The first object in the array is the name
* of the page. Any additional objects are service parameters to be
* supplied to the listener method.
*
* <p>
* The parameters are converted to an array of objects
* via {@link #convertParameters(String)}.
*
**/
protected Object[] constructExternalServiceParameters(String pageName, String parameters)
throws JspException
{
Object[] resolvedParameters = convertParameters(parameters);
int count = Tapestry.size(resolvedParameters);
if (count == 0)
return new Object[] { pageName };
List list = new ArrayList();
list.add(pageName);
for (int i = 0; i < count; i++)
list.add(resolvedParameters[i]);
return list.toArray();
}
/**
* <p>The external service allows service parameters (an array of
* objects) to be passed along inside the URL. This method converts
* the input string into an array of parameter objects.
* <ul>
* <li>If parameters is null, the no parameters are passed
* <li>If parameters starts with "ognl:" it is treated as an OGNL expression:
* <ul>
* <li>The expression is evaluated using the
* {@link javax.servlet.jsp.PageContext page context} as the root object
* <li>If the expression value is a Map, then the Map is converted to
* an array via (@link org.apache.tapestry.Tapestry#convertMapToArray(Map)}
* <li>Otherwise, the expression value is converted using
* {@link org.apache.tapestry.link.DirectLink#constructServiceParameters(Object)}.
* </ul>
* <li>Otherwise, parameters are simply a string, which is included as the lone
* service parameter
* </ul>
**/
protected Object[] convertParameters(String _parameters) throws JspException
{
if (_parameters == null)
return null;
if (_parameters.startsWith(TemplateParser.OGNL_EXPRESSION_PREFIX))
{
String expression =
_parameters.substring(TemplateParser.OGNL_EXPRESSION_PREFIX.length() + 1);
return convertExpression(expression);
}
return new Object[] { _parameters };
}
private Object[] convertExpression(String expression) throws JspException
{
Object value = evaluateExpression(expression);
if (value == null)
return null;
if (value instanceof Map)
return Tapestry.convertMapToArray((Map) value);
return DirectLink.constructServiceParameters(value);
}
private Object evaluateExpression(String expression) throws JspException
{
ClassResolver resolver = new DefaultClassResolver();
try
{
return OgnlUtils.get(expression, resolver, pageContext);
}
catch (Throwable t)
{
throw new JspException(
Tapestry.format(
"AbstractTapestryTag.unable-to-evaluate-expression",
expression,
t.getMessage()),
t);
}
}
}