org.apache.catalina.startup.LifecycleListenerRule Maven / Gradle / Ivy
/*
* 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 org.apache.catalina.startup;
import org.apache.catalina.Container;
import org.apache.catalina.LifecycleListener;
import org.apache.tomcat.util.IntrospectionUtils;
import org.apache.tomcat.util.digester.Rule;
import org.xml.sax.Attributes;
/**
* Rule that creates a new {@link LifecycleListener} and associates it with the
* top object on the stack which must implement {@link Container}. The
* implementation class to be used is determined by:
*
* - Does the top element on the stack specify an implementation class using
* the attribute specified when this rule was created?
* - Does the parent {@link Container} of the {@link Container} on the top of
* the stack specify an implementation class using the attribute specified
* when this rule was created?
* - Use the default implementation class specified when this rule was
* created.
*
*/
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 final String attributeName;
/**
* The name of the LifecycleListener implementation class.
*/
private final 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
*/
@Override
public void begin(String namespace, String name, Attributes attributes)
throws Exception {
Container c = (Container) digester.peek();
Container p = null;
Object obj = digester.peek(1);
if (obj instanceof Container) {
p = (Container) obj;
}
String className = null;
// Check the container for the specified attribute
if (attributeName != null) {
String value = attributes.getValue(attributeName);
if (value != null) {
className = value;
}
}
// Check the container's parent for the specified attribute
if (p != null && className == null) {
String configClass =
(String) IntrospectionUtils.getProperty(p, attributeName);
if (configClass != null && configClass.length() > 0) {
className = configClass;
}
}
// Use the default
if (className == null) {
className = listenerClass;
}
// Instantiate a new LifecycleListener implementation object
Class clazz = Class.forName(className);
LifecycleListener listener = (LifecycleListener) clazz.getConstructor().newInstance();
// Add this LifecycleListener to our associated component
c.addLifecycleListener(listener);
StringBuilder code = digester.getGeneratedCode();
if (code != null) {
code.append(digester.toVariableName(c)).append(".addLifecycleListener(");
code.append("new ").append(className).append("());").append(System.lineSeparator());
}
}
}