Java tutorial
/* * $Header: /home/cvs/jakarta-tomcat-catalina/catalina/src/share/org/apache/catalina/util/CatalinaDigester.java,v 1.1 2003/11/14 10:00:39 remm Exp $ * $Revision: 1.1 $ * $Date: 2003/11/14 10:00:39 $ * * ==================================================================== * * The Apache Software License, Version 1.1 * * Copyright (c) 1999 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, if * any, must include the following acknowlegement: * "This product includes software developed by the * Apache Software Foundation (http://www.apache.org/)." * Alternately, this acknowlegement may appear in the software itself, * if and wherever such third-party acknowlegements normally appear. * * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software * Foundation" must not be used to endorse or promote products derived * from this software without prior written permission. For written * permission, please contact apache@apache.org. * * 5. Products derived from this software may not be called "Apache" * nor may "Apache" appear in their names without prior written * permission of the Apache Group. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * * [Additional notices, if required by prior licensing conditions] * */ package org.apache.catalina.util; import org.apache.commons.digester.Digester; import org.xml.sax.Attributes; import org.xml.sax.helpers.AttributesImpl; import org.xml.sax.SAXException; import org.apache.tomcat.util.IntrospectionUtils; /** * This extended digester filters out ${...} tokens to replace them with * matching system properties. * * @author Simon Kitching * @author Remy Maucherat */ public class CatalinaDigester extends Digester { // ---------------------------------------------------------- Static Fields private static class SystemPropertySource implements IntrospectionUtils.PropertySource { public String getProperty(String key) { return System.getProperty(key); } } protected static IntrospectionUtils.PropertySource source[] = new IntrospectionUtils.PropertySource[] { new SystemPropertySource() }; // ---------------------------------------------------------------- Methods /** * Invoke inherited implementation after applying variable * substitution to any attribute values containing variable * references. */ public void startElement(String namespaceURI, String localName, String qName, Attributes list) throws SAXException { list = updateAttributes(list); super.startElement(namespaceURI, localName, qName, list); } /** * Invoke inherited implementation after applying variable substitution * to the character data contained in the current element. */ public void endElement(String namespaceURI, String localName, String qName) throws SAXException { bodyText = updateBodyText(bodyText); super.endElement(namespaceURI, localName, qName); } /** * Returns an attributes list which contains all the attributes * passed in, with any text of form "${xxx}" in an attribute value * replaced by the appropriate value from the system property. */ private Attributes updateAttributes(Attributes list) { if (list.getLength() == 0) { return list; } AttributesImpl newAttrs = new AttributesImpl(list); int nAttributes = newAttrs.getLength(); for (int i = 0; i < nAttributes; ++i) { String value = newAttrs.getValue(i); try { String newValue = IntrospectionUtils.replaceProperties(value, null, source); if (value != newValue) { newAttrs.setValue(i, newValue); } } catch (Exception e) { // ignore - let the attribute have its original value } } return newAttrs; } /** * Return a new StringBuffer containing the same contents as the * input buffer, except that data of form ${varname} have been * replaced by the value of that var as defined in the system property. */ private StringBuffer updateBodyText(StringBuffer bodyText) { String in = bodyText.toString(); String out; try { out = IntrospectionUtils.replaceProperties(in, null, source); } catch (Exception e) { return bodyText; // return unchanged data } if (out == in) { // No substitutions required. Don't waste memory creating // a new buffer return bodyText; } else { return new StringBuffer(out); } } }