container/catalina/src/share/org/apache/catalina/startup/LifecycleListenerRule.java

/*
 * Copyright 1999-2001,2004 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.catalina.startup;


import org.apache.catalina.Lifecycle;
import org.apache.catalina.LifecycleListener;
import org.apache.tomcat.util.digester.Rule;
import org.xml.sax.Attributes;


/**
 * <p>Rule that creates a new <code>LifecycleListener</code> instance,
 * and associates it with the top object on the stack (which must
 * implement <code>LifecycleListener</code>).</p>
 */

public class LifecycleListenerRule extends Rule {


    // ----------------------------------------------------------- Constructors


    /**
     * Construct a new instance of this Rule.
     *
     * @param listenerClass Default name of the LifecycleListener
     *  implementation class to be created
     * @param attributeName Name of the attribute that optionally
     *  includes an override name of the LifecycleListener class
     */
    public LifecycleListenerRule(String listenerClass, String attributeName) {

        this.listenerClass = listenerClass;
        this.attributeName = attributeName;

    }


    // ----------------------------------------------------- Instance Variables


    /**
     * The attribute name of an attribute that can override the
     * implementation class name.
     */
    private String attributeName;


    /**
     * The name of the <code>LifecycleListener</code> implementation class.
     */
    private String listenerClass;


    // --------------------------------------------------------- Public Methods


    /**
     * Handle the beginning of an XML element.
     *
     * @param attributes The attributes of this element
     *
     * @exception Exception if a processing error occurs
     */
    public void begin(String namespace, String name, Attributes attributes)
        throws Exception {

        // Instantiate a new LifecyleListener implementation object
        String className = listenerClass;
        if (attributeName != null) {
            String value = attributes.getValue(attributeName);
            if (value != null)
                className = value;
        }
        Class clazz = Class.forName(className);
        LifecycleListener listener =
            (LifecycleListener) clazz.newInstance();

        // Add this LifecycleListener to our associated component
        Lifecycle lifecycle = (Lifecycle) digester.peek();
        lifecycle.addLifecycleListener(listener);

    }


}