/**
*
* 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.
*/
package javax.availability.management;
/**
* @version $Rev$ $Date$
*/
public class AvailabilityAgentFactory {
private static final Object LOCK = new Object();
private static AvailabilityAgent agent;
public static synchronized AvailabilityAgent instantiateAvailabilityAgent() throws AvailabilityException {
synchronized (LOCK) {
if (agent != null) return agent;
String agentClassName = System.getProperty("javax.availability.management.agent");
if (agentClassName == null) throw new AvailabilityException("javax.availability.management.agent has not been set");
try {
Class<?> agentClass = Class.forName(agentClassName);
agent = (AvailabilityAgent) agentClass.newInstance();
} catch (ClassNotFoundException cnfe) {
throw new AvailabilityException("Unable to locate class " + agentClassName, cnfe);
} catch (InstantiationException ie) {
throw new AvailabilityException("Unable to instantiate class " + agentClassName, ie);
} catch (IllegalAccessException iae) {
throw new AvailabilityException("Unable to access class " + agentClassName, iae);
} catch (ClassCastException cce) {
throw new AvailabilityException("The class " + agentClassName + " does not implement AvailabilityAgent", cce);
}
return agent;
}
}
}