Java tutorial
package bboss.org.apache.velocity.runtime.resource.loader; /* * 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. */ import java.io.InputStream; import java.util.Hashtable; import java.util.Vector; import java.util.Map; import java.util.HashMap; import bboss.org.apache.velocity.util.StringUtils; import bboss.org.apache.velocity.runtime.resource.Resource; import bboss.org.apache.velocity.exception.ResourceNotFoundException; import org.apache.commons.collections.ExtendedProperties; /** * <p> * ResourceLoader to load templates from multiple Jar files. * </p> * <p> * The configuration of the JarResourceLoader is straightforward - * You simply add the JarResourceLoader to the configuration via * </p> * <p><pre> * resource.loader = jar * jar.resource.loader.class = bboss.org.apache.velocity.runtime.resource.loader.JarResourceLoader * jar.resource.loader.path = list of JAR <URL>s * </pre></p> * * <p> So for example, if you had a jar file on your local filesystem, you could simply do * <pre> * jar.resource.loader.path = jar:file:/opt/myfiles/jar1.jar * </pre> * </p> * <p> Note that jar specification for the <code>.path</code> configuration property * conforms to the same rules for the java.net.JarUrlConnection class. * </p> * * <p> For a working example, see the unit test case, * bboss.org.apache.velocity.test.MultiLoaderTestCase class * </p> * * @author <a href="mailto:mailmur@yahoo.com">Aki Nieminen</a> * @author <a href="mailto:daveb@miceda-data.com">Dave Bryson</a> * @version $Id: JarResourceLoader.java 691884 2008-09-04 06:46:51Z nbubna $ */ public class JarResourceLoader extends ResourceLoader { /** * Maps entries to the parent JAR File * Key = the entry *excluding* plain directories * Value = the JAR URL */ private Map entryDirectory = new HashMap(559); /** * Maps JAR URLs to the actual JAR * Key = the JAR URL * Value = the JAR */ private Map jarfiles = new HashMap(89); /** * Called by Velocity to initialize the loader * @param configuration */ public void init(ExtendedProperties configuration) { log.trace("JarResourceLoader : initialization starting."); // rest of Velocity engine still use legacy Vector // and Hashtable classes. Classes are implicitly // synchronized even if we don't need it. Vector paths = configuration.getVector("path"); StringUtils.trimStrings(paths); /* * support the old version but deprecate with a log message */ if (paths == null || paths.size() == 0) { paths = configuration.getVector("resource.path"); StringUtils.trimStrings(paths); if (paths != null && paths.size() > 0) { log.debug("JarResourceLoader : you are using a deprecated configuration" + " property for the JarResourceLoader -> '<name>.resource.loader.resource.path'." + " Please change to the conventional '<name>.resource.loader.path'."); } } if (paths != null) { log.debug("JarResourceLoader # of paths : " + paths.size()); for (int i = 0; i < paths.size(); i++) { loadJar((String) paths.get(i)); } } log.trace("JarResourceLoader : initialization complete."); } private void loadJar(String path) { if (log.isDebugEnabled()) { log.debug("JarResourceLoader : trying to load \"" + path + "\""); } // Check path information if (path == null) { String msg = "JarResourceLoader : can not load JAR - JAR path is null"; log.error(msg); throw new RuntimeException(msg); } if (!path.startsWith("jar:")) { String msg = "JarResourceLoader : JAR path must start with jar: -> see java.net.JarURLConnection for information"; log.error(msg); throw new RuntimeException(msg); } if (path.indexOf("!/") < 0) { path += "!/"; } // Close the jar if it's already open // this is useful for a reload closeJar(path); // Create a new JarHolder JarHolder temp = new JarHolder(rsvc, path); // Add it's entries to the entryCollection addEntries(temp.getEntries()); // Add it to the Jar table jarfiles.put(temp.getUrlPath(), temp); } /** * Closes a Jar file and set its URLConnection * to null. */ private void closeJar(String path) { if (jarfiles.containsKey(path)) { JarHolder theJar = (JarHolder) jarfiles.get(path); theJar.close(); } } /** * Copy all the entries into the entryDirectory * It will overwrite any duplicate keys. */ private void addEntries(Hashtable entries) { entryDirectory.putAll(entries); } /** * Get an InputStream so that the Runtime can build a * template with it. * * @param source name of template to get * @return InputStream containing the template * @throws ResourceNotFoundException if template not found * in the file template path. */ public InputStream getResourceStream(String source) throws ResourceNotFoundException { InputStream results = null; if (org.apache.commons.lang.StringUtils.isEmpty(source)) { throw new ResourceNotFoundException("Need to have a resource!"); } String normalizedPath = StringUtils.normalizePath(source); if (normalizedPath == null || normalizedPath.length() == 0) { String msg = "JAR resource error : argument " + normalizedPath + " contains .. and may be trying to access " + "content outside of template root. Rejected."; log.error("JarResourceLoader : " + msg); throw new ResourceNotFoundException(msg); } /* * if a / leads off, then just nip that :) */ if (normalizedPath.startsWith("/")) { normalizedPath = normalizedPath.substring(1); } if (entryDirectory.containsKey(normalizedPath)) { String jarurl = (String) entryDirectory.get(normalizedPath); if (jarfiles.containsKey(jarurl)) { JarHolder holder = (JarHolder) jarfiles.get(jarurl); results = holder.getResource(normalizedPath); return results; } } throw new ResourceNotFoundException("JarResourceLoader Error: cannot find resource " + source); } // TODO: SHOULD BE DELEGATED TO THE JARHOLDER /** * @see bboss.org.apache.velocity.runtime.resource.loader.ResourceLoader#isSourceModified(bboss.org.apache.velocity.runtime.resource.Resource) */ public boolean isSourceModified(Resource resource) { return true; } /** * @see bboss.org.apache.velocity.runtime.resource.loader.ResourceLoader#getLastModified(bboss.org.apache.velocity.runtime.resource.Resource) */ public long getLastModified(Resource resource) { return 0; } }