/*
* Copyright 2002-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.axis.configuration;
import org.apache.axis.AxisProperties;
import org.apache.axis.EngineConfigurationFactory;
import org.apache.axis.components.logger.LogFactory;
import org.apache.axis.utils.Messages;
import org.apache.commons.discovery.ResourceClassIterator;
import org.apache.commons.discovery.tools.ClassUtils;
import org.apache.commons.logging.Log;
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
{
protected static Log log =
LogFactory.getLog(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.apache.axis.configuration.EngineConfigurationFactoryServlet",
"org.apache.axis.configuration.EngineConfigurationFactoryDefault",
});
}
private EngineConfigurationFactoryFinder() {
}
/**
* Create the default engine configuration and detect whether the user
* has overridden this with their own.
*
* The discovery mechanism will use the following logic:
*
* - discover all available EngineConfigurationFactories
* - find all META-INF/services/org.apache.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
*
* ***
* 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;
}
}