/*
* Copyright (C) 2012 eXo Platform SAS.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.exoplatform.commons.utils;
import org.exoplatform.services.log.ExoLogger;
import org.exoplatform.services.log.Log;
/**
* @author <a href="abazko@exoplatform.com">Anatoliy Bazko</a>
* @version $Id: ClassLoading.java 34360 2009-07-22 23:58:59Z tolusha $
*/
public class ClassLoading
{
/**
* The logger
*/
private static final Log LOG = ExoLogger.getLogger("org.exoplatform.commons.utils.ClassLoader");
/**
* Loads the class using the ClassLoader corresponding to the caller object first,
* if class not found we try with Thread's context ClassLoader (TCCL).
* If the TCCL doesn't exist or the class still cannot be found, we use the
* System class loader.
*
* @param type FQN of class to load
* @param callerObject the object from which we want to load the class
* @return Loaded class
* @throws ClassNotFoundException
*/
public static Class<?> forName(String type, Object callerObject) throws ClassNotFoundException
{
return forName(type, callerObject.getClass());
}
/**
* Loads the class using the ClassLoader corresponding to the caller class first,
* if class not found we try with Thread's context ClassLoader (TCCL).
* If the TCCL doesn't exist or the class still cannot be found, we use the
* System class loader.
*
* @param type FQN of class to load
* @param callerClass the class from which we want to load the class
* @return Loaded class
* @throws ClassNotFoundException
*/
public static Class<?> forName(String type, Class<?> callerClass) throws ClassNotFoundException
{
try
{
// We first try with the local class loader
return Class.forName(type, true, callerClass.getClassLoader());
}
catch (ClassNotFoundException e)
{
if (LOG.isTraceEnabled())
{
LOG.trace("The class " + type + " could not be found in the Class loader of " + callerClass);
}
// Then we try with the Thread Context Class loader
ClassLoader cl = Thread.currentThread().getContextClassLoader();
try
{
if (cl != null)
{
return Class.forName(type, true, cl);
}
else if (LOG.isTraceEnabled())
{
LOG.trace("No thread context Class loader could be found to load the class " + type);
}
}
catch (ClassNotFoundException e1)
{
// ignore me
if (LOG.isTraceEnabled())
{
LOG.trace("The class " + type + " could not be found in the thread context Class loader");
}
cl = null;
}
// Finally we test with the system class loader
try
{
cl = ClassLoader.getSystemClassLoader();
}
catch (Exception e1)
{
// ignore me
if (LOG.isTraceEnabled())
{
LOG.trace("The system Class loader could not be found to load the class " + type, e1);
}
}
if (cl != null)
{
return Class.forName(type, true, cl);
}
else if (LOG.isTraceEnabled())
{
LOG.trace("The system Class loader could not be found to load the class " + type);
}
throw e;
}
}
/**
* Loads the class using the ClassLoader corresponding to the caller object first,
* if class not found we try with Thread's context ClassLoader (TCCL).
* If the TCCL doesn't exist or the class still cannot be found, we use the
* System class loader.
*
* @param type FQN of class to load
* @param callerObject the object from which we want to load the class
* @return Loaded class
* @throws ClassNotFoundException
*/
public static Class<?> loadClass(String type, Object callerObject) throws ClassNotFoundException
{
return loadClass(type, callerObject.getClass());
}
/**
* Loads the class using the ClassLoader corresponding to the caller class first,
* if class not found we try with Thread's context ClassLoader (TCCL).
* If the TCCL doesn't exist or the class still cannot be found, we use the
* System class loader.
*
* @param type FQN of class to load
* @param callerClass the class from which we want to load the class
* @return Loaded class
* @throws ClassNotFoundException
*/
public static Class<?> loadClass(String type, Class<?> callerClass) throws ClassNotFoundException
{
ClassLoader localCl = callerClass.getClassLoader();
try
{
return localCl.loadClass(type);
}
catch (ClassNotFoundException e)
{
if (LOG.isTraceEnabled())
{
LOG.trace("The class " + type + " could not be found in the Class loader of " + callerClass);
}
// Then we try with the Thread Context Class loader
ClassLoader cl = Thread.currentThread().getContextClassLoader();
try
{
if (cl != null)
{
return cl.loadClass(type);
}
else if (LOG.isTraceEnabled())
{
LOG.trace("No thread context Class loader could be found to load the class " + type);
}
}
catch (ClassNotFoundException e1)
{
// ignore me
if (LOG.isTraceEnabled())
{
LOG.trace("The class " + type + " could not be found in the thread context Class loader");
}
cl = null;
}
// Finally we test with the system class loader
try
{
cl = ClassLoader.getSystemClassLoader();
}
catch (Exception e1)
{
// ignore me
if (LOG.isTraceEnabled())
{
LOG.trace("The system Class loader could not be found to load the class " + type, e1);
}
}
if (cl != null)
{
return cl.loadClass(type);
}
else if (LOG.isTraceEnabled())
{
LOG.trace("The system Class loader could not be found to load the class " + type);
}
throw e;
}
}
}