001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.xbean.server.spring.configuration;
018    
019    import java.net.URL;
020    import java.util.ArrayList;
021    import java.util.List;
022    import java.util.ListIterator;
023    
024    import org.apache.xbean.classloader.JarFileClassLoader;
025    import org.apache.xbean.server.repository.Repository;
026    import org.apache.xbean.server.spring.loader.SpringLoader;
027    import org.apache.xbean.spring.context.SpringApplicationContext;
028    import org.apache.xbean.spring.context.SpringXmlPreprocessor;
029    import org.springframework.beans.FatalBeanException;
030    import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
031    import org.w3c.dom.Document;
032    import org.w3c.dom.Element;
033    import org.w3c.dom.NodeList;
034    import org.w3c.dom.Text;
035    
036    /**
037     * ClassLoaderXmlPreprocessor extracts a ClassLoader definition from the xml document, builds a class loader, assigns
038     * the class loader to the application context and xml reader, and removes the classpath element from document.
039     *
040     * @org.apache.xbean.XBean namespace="http://xbean.apache.org/schemas/server" element="class-loader-xml-preprocessor"
041     *     description="Extracts a ClassLoader definition from the xml document."
042     *
043     * @author Dain Sundstrom
044     * @version $Id$
045     * @since 2.0
046     */
047    public class ClassLoaderXmlPreprocessor implements SpringXmlPreprocessor {
048        private final Repository repository;
049    
050        /**
051         * Creates a ClassLoaderXmlPreprocessor that uses the specified repository to resolve the class path locations.
052         * @param repository the repository used to resolve the class path locations
053         */
054        public ClassLoaderXmlPreprocessor(Repository repository) {
055            this.repository = repository;
056        }
057    
058        /**
059         * Extracts a ClassLoader definition from the xml document, builds a class loader, assigns
060         * the class loader to the application context and xml reader, and removes the classpath element from document.
061         *
062         * @param applicationContext the application context on which the class loader will be set
063         * @param reader the xml reader on which the class loader will be set
064         * @param document the xml document to inspect
065         */
066        public void preprocess(SpringApplicationContext applicationContext, XmlBeanDefinitionReader reader, Document document) {
067            // determine the classLoader
068            ClassLoader classLoader;
069            NodeList classpathElements = document.getDocumentElement().getElementsByTagName("classpath");
070            if (classpathElements.getLength() < 1) {
071                classLoader = getClassLoader(applicationContext);
072            } else if (classpathElements.getLength() > 1) {
073                throw new FatalBeanException("Expected only classpath element but found " + classpathElements.getLength());
074            } else {
075                Element classpathElement = (Element) classpathElements.item(0);
076                
077                // Delegation mode
078                boolean inverse = false;
079                String inverseAttr = classpathElement.getAttribute("inverse");
080                if (inverseAttr != null && "true".equalsIgnoreCase(inverseAttr)) {
081                    inverse = true;
082                }
083    
084                // build hidden classes
085                List hidden = new ArrayList();
086                NodeList hiddenElems = classpathElement.getElementsByTagName("hidden");
087                for (int i = 0; i < hiddenElems.getLength(); i++) {
088                    Element hiddenElement = (Element) hiddenElems.item(i);
089                    String pattern = ((Text) hiddenElement.getFirstChild()).getData().trim();
090                    hidden.add(pattern);
091                }
092    
093                // build non overridable classes
094                List nonOverridable = new ArrayList();
095                NodeList nonOverridableElems = classpathElement.getElementsByTagName("nonOverridable");
096                for (int i = 0; i < nonOverridableElems.getLength(); i++) {
097                    Element nonOverridableElement = (Element) nonOverridableElems.item(i);
098                    String pattern = ((Text) nonOverridableElement.getFirstChild()).getData().trim();
099                    nonOverridable.add(pattern);
100                }
101    
102                // build the classpath
103                List classpath = new ArrayList();
104                NodeList locations = classpathElement.getElementsByTagName("location");
105                for (int i = 0; i < locations.getLength(); i++) {
106                    Element locationElement = (Element) locations.item(i);
107                    String location = ((Text) locationElement.getFirstChild()).getData().trim();
108                    classpath.add(location);
109                }
110                
111                // convert the paths to URLS
112                URL[] urls = new URL[classpath.size()];
113                for (ListIterator iterator = classpath.listIterator(); iterator.hasNext();) {
114                    String location = (String) iterator.next();
115                    URL url = repository.getResource(location);
116                    if (url == null) {
117                        throw new FatalBeanException("Unable to resolve classpath location " + location);
118                    }
119                    urls[iterator.previousIndex()] = url;
120                }
121    
122                // create the classloader
123                ClassLoader parentLoader = getClassLoader(applicationContext);
124                classLoader = new JarFileClassLoader(applicationContext.getDisplayName(), 
125                                                     urls, 
126                                                     parentLoader,
127                                                     inverse,
128                                                     (String[]) hidden.toArray(new String[hidden.size()]),
129                                                     (String[]) nonOverridable.toArray(new String[nonOverridable.size()]));
130    
131                // remove the classpath element so Spring doesn't get confused
132                document.getDocumentElement().removeChild(classpathElement);
133            }
134    
135            // assign the class loader to the xml reader and the application context
136            reader.setBeanClassLoader(classLoader);
137            applicationContext.setClassLoader(classLoader);
138            Thread.currentThread().setContextClassLoader(classLoader);
139        }
140    
141        private static ClassLoader getClassLoader(SpringApplicationContext applicationContext) {
142            ClassLoader classLoader = applicationContext.getClassLoader();
143            if (classLoader == null) {
144                classLoader = Thread.currentThread().getContextClassLoader();
145            }
146            if (classLoader == null) {
147                classLoader = SpringLoader.class.getClassLoader();
148            }
149            return classLoader;
150        }
151        
152    }