/*
* $Header: /cvsroot/jaxen/jaxen/src/java/main/org/jaxen/saxpath/helpers/XPathReaderFactory.java,v 1.1 2003/06/29 18:10:56 ssanders Exp $
* $Revision: 1.1 $
* $Date: 2003/06/29 18:10:56 $
*
* ====================================================================
*
* Copyright (C) 2000-2002 werken digital.
* 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 disclaimer that follows
* these conditions in the documentation and/or other materials
* provided with the distribution.
*
* 3. The name "SAXPath" must not be used to endorse or promote products
* derived from this software without prior written permission. For
* written permission, please contact license@saxpath.org.
*
* 4. Products derived from this software may not be called "SAXPath", nor
* may "SAXPath" appear in their name, without prior written permission
* from the SAXPath Project Management (pm@saxpath.org).
*
* In addition, we request (but do not require) that you include in the
* end-user documentation provided with the redistribution and/or in the
* software itself an acknowledgement equivalent to the following:
* "This product includes software developed by the
* SAXPath Project (http://www.saxpath.org/)."
* Alternatively, the acknowledgment may be graphical using the logos
* available at http://www.saxpath.org/
*
* 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 SAXPath AUTHORS OR THE PROJECT
* 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 SAXPath Project and was originally
* created by bob mcwhirter <bob@werken.com> and
* James Strachan <jstrachan@apache.org>. For more information on the
* SAXPath Project, please see <http://www.saxpath.org/>.
*
* $Id: XPathReaderFactory.java,v 1.1 2003/06/29 18:10:56 ssanders Exp $
*/
package org.jaxen.saxpath.helpers;
import org.jaxen.saxpath.XPathReader;
/** Create an {@link org.jaxen.saxpath.XPathReader} from
* either a system property, or a named class.
*
* <p>
* Similar to the SAX API, the <code>XPathReaderFactory</code>
* can create an <code>XPathReader</code> from a name of a
* class passed in directly, or by inspecting the system
* property <code>org.saxpath.driver</code>.
*
* @author bob mcwhirter (bob@werken.com)
*/
public class XPathReaderFactory
{
/** The <code>org.saxpath.driver</code> property name. */
public static final String DRIVER_PROPERTY = "org.saxpath.driver";
/** The default driver to use if none is configured. */
protected static final String DEFAULT_DRIVER = "org.jaxen.saxpath.base.XPathReader";
/** Should the default driver be used */
private static boolean USE_DEFAULT = true;
/** Create an <code>XPathReader</code> using the value of
* the <code>org.saxpath.driver</code> system property.
*
* @return An instance of the <code>XPathReader</code> specified
* by the <code>org.saxpath.driver</code> property.
*
* @throws org.jaxen.saxpath.SAXPathException if the property is unset, or if
* the class can not be instantiated for some reason.,
* or if the class doesn't implement the <code>XPathReader</code>
* interface.
*/
public static XPathReader createReader() throws org.jaxen.saxpath.SAXPathException
{
String className = null;
boolean securityException = false;
try
{
className = System.getProperty( DRIVER_PROPERTY );
}
catch (SecurityException e)
{
securityException = true;
}
if ( className == null
||
"".equals( className ) )
{
if ( USE_DEFAULT )
{
className = DEFAULT_DRIVER;
}
else
{
if ( securityException )
{
throw new org.jaxen.saxpath.SAXPathException( "Reading of property " + DRIVER_PROPERTY + " disallowed." );
}
else
{
throw new org.jaxen.saxpath.SAXPathException( "Property " + DRIVER_PROPERTY + " not set" );
}
}
}
return createReader( className );
}
/** Create an <code>XPathReader</code> using the passed
* in class name.
*
* @param className The name of the class which implements
* the <code>XPathReader</code> interface.
*
* @throws org.jaxen.saxpath.SAXPathException if the class can not be
* instantiated for some reason, or if the
* class doesn't implement the <code>XPathReader</code>
* interface.
*/
public static XPathReader createReader(String className) throws org.jaxen.saxpath.SAXPathException
{
Class readerClass = null;
XPathReader reader = null;
try
{
// Use the full version of Class.forName(), so as to
// work better in sandboxed environments, such as
// Servlet contains, and Applets.
readerClass = Class.forName( className,
true,
XPathReaderFactory.class.getClassLoader() );
// Double-check that it's actually the right kind of class
// before attempting instantiation.
if ( ! XPathReader.class.isAssignableFrom( readerClass ) )
{
throw new org.jaxen.saxpath.SAXPathException( "Class [" + className + "] does not implement the org.jaxen.saxpath.XPathReader interface." );
}
}
catch (ClassNotFoundException e)
{
throw new org.jaxen.saxpath.SAXPathException( e.getMessage() );
}
try
{
reader = (XPathReader) readerClass.newInstance();
}
catch (IllegalAccessException e)
{
throw new org.jaxen.saxpath.SAXPathException( e.getMessage() );
}
catch (InstantiationException e)
{
throw new org.jaxen.saxpath.SAXPathException( e.getMessage() );
}
if ( reader == null )
{
throw new org.jaxen.saxpath.SAXPathException( "Unable to create XPathReader" );
}
return reader;
}
}