org.apache.tomcat.util.digester.ObjectCreateRule Maven / Gradle / Ivy
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Common code shared by Catalina and Jasper for scanning JARS and processing
XML descriptors
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/*
* 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.tomcat.util.digester;
import org.xml.sax.Attributes;
/**
* Rule implementation that creates a new object and pushes it
* onto the object stack. When the element is complete, the
* object will be popped
*/
public class ObjectCreateRule extends Rule {
// ----------------------------------------------------------- Constructors
/**
* Construct an object create rule with the specified class name.
*
* @param className Java class name of the object to be created
*/
public ObjectCreateRule(String className) {
this(className, null);
}
/**
* Construct an object create rule with the specified class name and an
* optional attribute name containing an override.
*
* @param className Java class name of the object to be created
* @param attributeName Attribute name which, if present, contains an
* override of the class name to create
*/
public ObjectCreateRule(String className,
String attributeName) {
this.className = className;
this.attributeName = attributeName;
}
// ----------------------------------------------------- Instance Variables
/**
* The attribute containing an override class name if it is present.
*/
protected String attributeName = null;
/**
* The Java class name of the object to be created.
*/
protected String className = null;
// --------------------------------------------------------- Public Methods
/**
* Process the beginning of this element.
*
* @param namespace the namespace URI of the matching element, or an
* empty string if the parser is not namespace aware or the element has
* no namespace
* @param name the local name if the parser is namespace aware, or just
* the element name otherwise
* @param attributes The attribute list for this element
*/
@Override
public void begin(String namespace, String name, Attributes attributes)
throws Exception {
String realClassName = getRealClassName(attributes);
if (realClassName == null) {
throw new NullPointerException(sm.getString("rule.noClassName", namespace, name));
}
// Instantiate the new object and push it on the context stack
Class clazz = digester.getClassLoader().loadClass(realClassName);
Object instance = clazz.getConstructor().newInstance();
digester.push(instance);
StringBuilder code = digester.getGeneratedCode();
if (code != null) {
code.append(System.lineSeparator());
code.append(System.lineSeparator());
code.append(realClassName).append(' ').append(digester.toVariableName(instance)).append(" = new ");
code.append(realClassName).append("();").append(System.lineSeparator());
}
}
/**
* Return the actual class name of the class to be instantiated.
* @param attributes The attribute list for this element
* @return the class name
*/
protected String getRealClassName(Attributes attributes) {
// Identify the name of the class to instantiate
String realClassName = className;
if (attributeName != null) {
String value = attributes.getValue(attributeName);
if (value != null) {
realClassName = value;
}
}
return realClassName;
}
/**
* Process the end of this element.
*
* @param namespace the namespace URI of the matching element, or an
* empty string if the parser is not namespace aware or the element has
* no namespace
* @param name the local name if the parser is namespace aware, or just
* the element name otherwise
*/
@Override
public void end(String namespace, String name) throws Exception {
Object top = digester.pop();
if (digester.log.isTraceEnabled()) {
digester.log.trace("[ObjectCreateRule]{" + digester.match +
"} Pop " + top.getClass().getName());
}
}
/**
* Render a printable version of this Rule.
*/
@Override
public String toString() {
StringBuilder sb = new StringBuilder("ObjectCreateRule[");
sb.append("className=");
sb.append(className);
sb.append(", attributeName=");
sb.append(attributeName);
sb.append(']');
return sb.toString();
}
}