/* ====================================================================== The Bodington System Software License, Version 1.0 Copyright (c) 2001 The University of Leeds. 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 acknowledgement: "This product includes software developed by the University of Leeds (http://www.bodington.org/)." Alternately, this acknowledgement may appear in the software itself, if and wherever such third-party acknowledgements normally appear. 4. The names "Bodington", "Nathan Bodington", "Bodington System", "Bodington Open Source Project", and "The University of Leeds" must not be used to endorse or promote products derived from this software without prior written permission. For written permission, please contact d.gardner@leeds.ac.uk. 5. The name "Bodington" may not appear in the name of products derived from this software without prior written permission of the University of Leeds. THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, TITLE, THE IMPLIED WARRANTIES OF QUALITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OF LEEDS 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 was originally created by the University of Leeds and may contain voluntary contributions from others. For more information on the Bodington Open Source Project, please see http://bodington.org/ ====================================================================== */ /* * XmlTemplateClassLoader.java * * Created on 13 June 2002, 09:49 */ package org.bodington.servlet.template; import java.io.File; import java.net.*; import java.util.Hashtable; import org.apache.log4j.Logger; /** * @author bmb6jrm */ public class XmlTemplateClassLoader extends URLClassLoader { private static Logger log = Logger.getLogger(XmlTemplateClassLoader.class); // indicates whether the class loader is the main classloader // or a delegated classloader private boolean is_delegated; // the delegated class has to be of same type as this // main class in order to access protected methods private XmlTemplateClassLoader delegated_class_loader; private int reload_count=0; private File directory; private Hashtable class_file_timestamps = new Hashtable(); private static URL[] getURLList( File directory ) { try { String path = directory.getAbsolutePath(); path.replace( '\\', '/' ); if ( !path.endsWith( "/" ) ) path = path + "/"; URL[] urls = new URL[1]; urls[0] = new URL( "file", "", path ); return urls; } catch ( MalformedURLException e ) { log.error( e.getMessage(), e ); return null; } } /** This public constructor is used to instantiate the main classloader * for a particular template directory. The class loader instatiated may * delegate class loading to a URLClassLoader if a fresh class loader is * required. */ public XmlTemplateClassLoader( File directory, ClassLoader parent ) { super( getURLList( directory ), parent ); this.directory = directory; is_delegated = false; // use the private constructor that makes the class behave just like // a URLClassLoader. delegated_class_loader = new XmlTemplateClassLoader( this, parent ); reload_count++; } private XmlTemplateClassLoader( XmlTemplateClassLoader main_classloader, ClassLoader parent ) { super( getURLList( main_classloader.directory ), parent ); is_delegated = true; this.directory = main_classloader.directory; // the delegated class loader is a stand alone class with no parent delegated_class_loader = null; } public File getClassFile( String name ) { String class_file_name; class_file_name = name.replace( '.', File.separatorChar ) + ".class"; File class_file = new File( directory, class_file_name ); if ( class_file.exists() && class_file.isFile() ) return class_file; return null; } private synchronized boolean isClassRecompiled( File class_file ) { Long old_timestamp; long new_timestamp=0L; if ( class_file == null ) return false; old_timestamp = (Long)class_file_timestamps.get( class_file.getAbsolutePath() ); new_timestamp = class_file.lastModified(); return old_timestamp!=null && new_timestamp > old_timestamp.longValue(); } public synchronized boolean isClassRecompiled( String name ) { if ( name == null ) return false; return isClassRecompiled( getClassFile( name ) ); } protected Class findClass(String name) throws ClassNotFoundException { return super.findClass( name ); } protected synchronized Class loadClass( String name, boolean resolve ) throws ClassNotFoundException { // a delegated class loader should just behave like a URLClassLoader if ( is_delegated ) return super.loadClass( name, resolve ); // a main class loader should check timestamps and then delegate Class the_class; File class_file; class_file = getClassFile( name ); if ( class_file == null ) throw new ClassNotFoundException( "Class not found: " + name ); // if the class file has been loaded before but has been updated // since then we must create a new delegated class loader if ( isClassRecompiled( class_file ) ) { // use the private constructor that makes the class behave just like // a URLClassLoader. delegated_class_loader = new XmlTemplateClassLoader( this, getParent() ); reload_count++; } the_class = delegated_class_loader.loadClass( name, resolve ); // record the new timestamp of the class file that was found. class_file_timestamps.put( class_file.getAbsolutePath(), new Long( class_file.lastModified() ) ); return the_class; } }