| EngineConfigurationFactoryFinder.java |
/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 2002-2003 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 "Axis" 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
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* 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.jboss.axis.configuration;
import org.apache.commons.discovery.ResourceClassIterator;
import org.apache.commons.discovery.tools.ClassUtils;
import org.jboss.axis.AxisProperties;
import org.jboss.axis.EngineConfigurationFactory;
import org.jboss.axis.utils.Messages;
import org.jboss.logging.Logger;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.PrivilegedAction;
/**
* This is a default implementation of EngineConfigurationFactory.
* It is user-overrideable by a system property without affecting
* the caller. If you decide to override it, use delegation if
* you want to inherit the behaviour of this class as using
* class extension will result in tight loops. That is, your
* class should implement EngineConfigurationFactory and keep
* an instance of this class in a member field and delegate
* methods to that instance when the default behaviour is
* required.
*
* @author Richard A. Sitze
*/
public class EngineConfigurationFactoryFinder
{
private static Logger log = Logger.getLogger(EngineConfigurationFactoryFinder.class.getName());
private static final Class mySpi = EngineConfigurationFactory.class;
private static final Class[] newFactoryParamTypes =
new Class[]{Object.class};
private static final String requiredMethod =
"public static EngineConfigurationFactory newFactory(Object)";
static
{
AxisProperties.setClassOverrideProperty(EngineConfigurationFactory.class,
EngineConfigurationFactory.SYSTEM_PROPERTY_NAME);
AxisProperties.setClassDefaults(EngineConfigurationFactory.class,
new String[]{
"org.jboss.axis.configuration.EngineConfigurationFactoryServlet",
"org.jboss.axis.configuration.EngineConfigurationFactoryDefault",
});
}
private EngineConfigurationFactoryFinder()
{
}
/**
* Create the default engine configuration and detect whether the user
* has overridden this with their own.
* <p/>
* The discovery mechanism will use the following logic:
* <p/>
* - discover all available EngineConfigurationFactories
* - find all META-INF/services/org.jboss.axis.EngineConfigurationFactory
* files available through class loaders.
* - read files (see Discovery) to obtain implementation(s) of that
* interface
* - For each impl, call 'newFactory(Object param)'
* - Each impl should examine the 'param' and return a new factory ONLY
* - if it knows what to do with it
* (i.e. it knows what to do with the 'real' type)
* - it can find it's configuration information
* - Return first non-null factory found.
* - Try EngineConfigurationFactoryServlet.newFactory(obj)
* - Try EngineConfigurationFactoryDefault.newFactory(obj)
* - If zero found (all return null), throw exception
* <p/>
* ***
* This needs more work: System.properties, etc.
* Discovery will have more tools to help with that
* (in the manner of use below) in the near future.
* ***
*/
public static EngineConfigurationFactory newFactory(final Object obj)
{
/**
* recreate on each call is critical to gaining
* the right class loaders. Do not cache.
*/
final Object[] params = new Object[]{obj};
/**
* Find and examine each service
*/
return (EngineConfigurationFactory)AccessController.doPrivileged(new PrivilegedAction()
{
public Object run()
{
ResourceClassIterator services = AxisProperties.getResourceClassIterator(mySpi);
EngineConfigurationFactory factory = null;
while (factory == null && services.hasNext())
{
try
{
Class service = services.nextResourceClass().loadClass();
/* service == null
* if class resource wasn't loadable
*/
if (service != null)
{
factory = newFactory(service, newFactoryParamTypes, params);
}
}
catch (Exception e)
{
// there was an exception creating the factory
// the most likely cause was the JDK 1.4 problem
// in the discovery code that requires servlet.jar
// to be in the client classpath. For now, fall
// through to the next factory
}
}
if (factory != null)
{
if (log.isDebugEnabled())
{
log.debug(Messages.getMessage("engineFactory", factory.getClass().getName()));
}
}
else
{
log.error(Messages.getMessage("engineConfigFactoryMissing"));
// we should be throwing an exception here,
//
// but again, requires more refactoring than we want to swallow
// at this point in time. Ifthis DOES occur, it's a coding error:
// factory should NEVER be null.
// Testing will find this, as NullPointerExceptions will be generated
// elsewhere.
}
return factory;
}
});
}
public static EngineConfigurationFactory newFactory()
{
return newFactory(null);
}
private static EngineConfigurationFactory newFactory(Class service,
Class[] paramTypes,
Object[] param)
{
/**
* Some JDK's may link on method resolution (findPublicStaticMethod)
* and others on method call (method.invoke).
*
* Either way, catch class load/resolve problems and return null.
*/
try
{
/**
* Verify that service implements:
* public static EngineConfigurationFactory newFactory(Object);
*/
Method method = ClassUtils.findPublicStaticMethod(service,
EngineConfigurationFactory.class,
"newFactory",
paramTypes);
if (method == null)
{
log.warn(Messages.getMessage("engineConfigMissingNewFactory",
service.getName(),
requiredMethod));
}
else
{
try
{
return (EngineConfigurationFactory)method.invoke(null, param);
}
catch (InvocationTargetException e)
{
if (e.getTargetException() instanceof NoClassDefFoundError)
{
log.debug(Messages.getMessage("engineConfigLoadFactory",
service.getName()));
}
else
{
log.warn(Messages.getMessage("engineConfigInvokeNewFactory",
service.getName(),
requiredMethod), e);
}
}
catch (Exception e)
{
log.warn(Messages.getMessage("engineConfigInvokeNewFactory",
service.getName(),
requiredMethod), e);
}
}
}
catch (NoClassDefFoundError e)
{
log.debug(Messages.getMessage("engineConfigLoadFactory",
service.getName()));
}
return null;
}
}
| EngineConfigurationFactoryFinder.java |