/*
============================================================================
The Apache Software License, Version 1.1
============================================================================
Copyright (C) 1999-2003 The Apache Software Foundation. All rights reserved.
Redistribution and use in source and binary forms, with or without modifica-
tion, 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 Cocoon" and "Apache Software Foundation" 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", 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 (INCLU-
DING, 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 and was originally created by
Stefano Mazzocchi <stefano@apache.org>. For more information on the Apache
Software Foundation, please see <http://www.apache.org/>.
*/
package org.apache.cocoon.selection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Map;
import org.apache.avalon.framework.logger.AbstractLogEnabled;
import org.apache.avalon.framework.parameters.Parameters;
import org.apache.avalon.framework.thread.ThreadSafe;
import org.apache.cocoon.environment.Context;
import org.apache.cocoon.environment.ObjectModelHelper;
/**
* Selects the first of a set of Resources (usually files) that exists in the
* context.
* <p>
* The 'test' expression is interpreted as a context-rooted ('/' = context)
* path, resolved by the servlet container, <em>not</em> a Source.
* <p>
* A parameter,
* <pre>
* <map:parameter src="prefix" value="<code>/</code>"/>
* </pre>
* may be supplied to the selector instance. This prefix is prepended to all
* test expressions before evaluation. The default prefix is '<code>/</code>',
* meaning that all expressions are context root-relative, unless explicitly
* overridden.
* <p>
* For example, we could define a ResourceExistsSelector with:
* <pre>
* <map:selector name="resource-exists"
* logger="sitemap.selector.resource-exists"
* src="org.apache.cocoon.selection.ResourceExistsSelector" />
* </pre>
* And use it to build a PDF from XSL:FO or a higher-level XML format with:
*
* <pre>
* <map:match pattern="**.pdf">
* <map:select type="resource-exists">
* <map:when test="context/xdocs/{1}.fo">
* <map:generate src="content/xdocs/{1}.fo" />
* </map:when>
* <map:otherwise>
* <map:generate src="content/xdocs/{1}.xml" />
* <map:transform src="stylesheets/document2fo.xsl" />
* </map:otherwise>
* </map:select>
* <map:serialize type="fo2pdf" />
* </pre>
*
* @author <a href="mailto:jefft@apache.org">Jeff Turner</a>
* @version CVS $Id: ResourceExistsSelector.java,v 1.2 2003/03/20 12:32:18 cziegeler Exp $
*/
public class ResourceExistsSelector extends AbstractLogEnabled
implements ThreadSafe, Selector {
public boolean select(String expression, Map objectModel, Parameters parameters) {
Context context = ObjectModelHelper.getContext(objectModel);
URL url = null;
expression = parameters.getParameter("prefix", "/") + expression;
try {
url = context.getResource(expression);
if (url == null) {
return false;
} else { return true; }
} catch (MalformedURLException e) {
getLogger().warn("Selector expression '"+expression+"' is not a valid URL");
return false;
}
/* While the servlet Javadocs state that getResource should return null
* if a resource doesn't exist, early versions of Tomcat didn't respect
* this. If this turns to be an issue with other containers, remove
* the 'else return true' above and uncomment this code. (JT)
InputStream is = null;
try {
is = url.openStream();
return true;
} catch (IOException e) {
return false;
} finally {
try {
if (is != null) is.close();
} catch (IOException e) {}
}
*/
}
}