|
/*
* $Id: ClassUtil.java 709153 2008-10-30 12:54:10Z apetrelli $
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
/**
* Utilities to work with dynamic class loading and instantiation.
*
* @version $Rev: 709153 $ $Date: 2008-10-30 13:54:10 +0100 (Thu, 30 Oct 2008) $
* @since 2.0.7
*/
public class Main {
/**
* Returns an instance of the given class name, by calling the default
* constructor.
*
* @param className The class name to load and to instantiate.
* @param returnNull If <code>true</code>, if the class is not found it
* returns <code>true</code>, otherwise it throws a
* <code>TilesException</code>.
* @return The new instance of the class name.
* @throws CannotInstantiateObjectException If something goes wrong during instantiation.
* @since 2.0.7
*/
public static Object instantiate(String className, boolean returnNull) {
ClassLoader original = Thread.currentThread().getContextClassLoader();
if (original == null) {
Thread.currentThread().setContextClassLoader(Main.class.getClassLoader());
}
try {
Class<?> namedClass = Class.forName(className);
return namedClass.newInstance();
} catch (ClassNotFoundException e) {
if (returnNull) {
return null;
}
throw new RuntimeException(
"Unable to resolve factory class: '" + className + "'", e);
} catch (IllegalAccessException e) {
throw new RuntimeException(
"Unable to access factory class: '" + className + "'", e);
} catch (InstantiationException e) {
throw new RuntimeException(
"Unable to instantiate factory class: '"
+ className
+ "'. Make sure that this class has a default constructor",
e);
} finally {
// If the original context classloader of the current thread was
// null, it must be reset.
if (original == null) {
Thread.currentThread().setContextClassLoader(null);
}
}
}
}
|