| /* |
| * Copyright 1999,2004 The Apache Software Foundation. |
| * |
| * Licensed 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.log4j.chainsaw.help; |
| |
| import java.net.MalformedURLException; |
| import java.net.URL; |
| import java.net.URLClassLoader; |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.Iterator; |
| import java.util.List; |
| |
| import org.apache.log4j.LogManager; |
| import org.apache.log4j.Logger; |
| import org.apache.log4j.chainsaw.messages.MessageCenter; |
| |
| /** |
| * A helper class that assists the HelpManager by serving as a collection of |
| * Class loaders based on URL roots. |
| * |
| * @author Paul Smith |
| * <psmith@apache.org> |
| */ |
| class HelpLocator { |
| private List classLoaders = new ArrayList(); |
| private static Logger logger = LogManager.getLogger(HelpLocator.class); |
| HelpLocator() { |
| } |
| |
| /** |
| * Adds a ClassLoader to be used as a help resource locator |
| */ |
| void installClassloaderLocator(ClassLoader cl) { |
| classLoaders.add(cl); |
| } |
| /** |
| * Adds a new locator to the current set of locators by using the passed in |
| * URL as a base to locate help resources. The URL SHOULD end in a '/' |
| * character. |
| */ |
| void installLocator(URL url) { |
| try { |
| classLoaders.add(new HelpResourceLoader(url)); |
| } catch (Exception e) { |
| MessageCenter.getInstance().getLogger().error( |
| "Failed to setup the resoure loaders for the Help Subsystem"); |
| } |
| } |
| |
| /** |
| * Locates a help resource by using the internal resource locator collection. |
| * |
| * @return URL of the located resource, or null if it cannot be located. |
| */ |
| URL findResource(String name) { |
| URL url = null; |
| |
| for (Iterator iter = classLoaders.iterator(); iter.hasNext();) { |
| ClassLoader loader = (ClassLoader) iter.next(); |
| url = loader.getResource(name); |
| |
| if (url != null) { |
| break; |
| } |
| } |
| |
| return url; |
| } |
| |
| private static class HelpResourceLoader extends ClassLoader { |
| private URL root; |
| |
| private HelpResourceLoader(URL root) { |
| this.root = root; |
| } |
| |
| /* |
| * (non-Javadoc) |
| * |
| * @see java.lang.ClassLoader#findResource(java.lang.String) |
| */ |
| protected URL findResource(String name) { |
| URL url = super.findResource(name); |
| |
| if (url != null) { |
| return url; |
| } |
| |
| try { |
| URL resourceURL = new URL(root, name); |
| URL[] urlArray = new URL[] { root, resourceURL }; |
| logger.debug("Looking for Help resource at:" + resourceURL.toExternalForm()); |
| logger.debug("urlArray=" + Arrays.asList(urlArray)); |
| return new URLClassLoader( |
| urlArray).findResource( |
| name); |
| } catch (MalformedURLException e) { |
| e.printStackTrace(); |
| } |
| |
| return null; |
| } |
| } |
| |
| // public static void main(String[] args) throws Exception { |
| // HelpLocator locator = new HelpLocator(); |
| // locator.installLocator(new File(".").toURL()); |
| // locator.installLocator(new |
| // URL("http://java.sun.com/j2se/1.4.2/docs/api/")); |
| // String[] resources = |
| // new String[] { "build.properties", "java/lang/ClassLoader.html", }; |
| // |
| // for (int i = 0; i < resources.length; i++) { |
| // String resource = resources[i]; |
| // URL url = locator.findResource(resource); |
| // System.out.println("resource=" + resource + ", url=" + url); |
| // } |
| // } |
| } |