/* SystemClassLoader.java -- the default system class loader Copyright (C) 1998, 1999, 2001, 2002 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version. */ package gnu.java.lang; import java.io.File; import java.net.MalformedURLException; import java.net.URL; import java.util.StringTokenizer; import java.util.zip.ZipFile; import java.util.zip.ZipEntry; /** * The default system class loader. VMs may wish to replace this with a * similar class that interacts better with their VM. Also, replacing this * class may be necessary when porting to new platforms, like Windows. * * XXX Should this be merged with ClassLoaderHelper? They both do a similar * search of the classpath, including jar/zip files. * * @author John Keiser * @author Mark Wielaard * @author Eric Blake */ public class SystemClassLoader extends ClassLoader { /** A lock for synchronization when reading jars. */ private static final Object NO_SUCH_ARCHIVE = new Object(); /** Flag to avoid infinite loops. */ private static boolean is_trying; /** * Get the URL to a resource. * * @param name the name of the resource * @return the URL to the resource */ public URL getResource(String name) { return systemGetResource(name); } /** * Get the URL to a resource. * * @param name the name of the resource * @return the URL to the resource */ public static URL systemGetResource(String name) { if (name.charAt(0) == '/') name = name.substring(1); String cp = System.getProperty("java.class.path", "."); StringTokenizer st = new StringTokenizer(cp, File.pathSeparator); while (st.hasMoreTokens()) { String path = st.nextToken(); if (path.toLowerCase().endsWith(".zip") || path.toLowerCase().endsWith(".jar")) { if (is_trying) // Avoid infinite loop. continue; File f = new File(path); if (! f.exists()) continue; path = f.getAbsolutePath(); ZipFile zf; try { synchronized (NO_SUCH_ARCHIVE) { is_trying = true; zf = gnu.java.net.protocol.jar.JarURLConnection .JarFileCache.get(new URL("file://" + path)); is_trying = false; } if (zf == null) continue; } catch (Exception e) { continue; } ZipEntry ze = zf.getEntry(name); if (ze == null) continue; try { if (path.charAt(0) == '/') return new URL("jar:file:/" + path + "!/" + name); else return new URL("jar:file://" + path + "!/" + name); } catch (MalformedURLException e) { continue; } } File f; if (path.endsWith(File.separator)) f = new File(path + name); else f = new File(path + File.separator + name); if (f.exists()) try { return new URL("file://" + f.getAbsolutePath()); } catch (MalformedURLException e) { continue; } } return null; } }