Java tutorial
/* * Java Terrain and Stellar System Ports * * Copyright (C) 2006 Martin H. Smith based on work by original * authors. * * Released under the terms of the GNU General Public License * * This program 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 * of the License, or (at your option) any later version. * * This program 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 this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, * MA 02110-1301, USA. * * Linking TerraJ statically or dynamically with other modules is making a * combined work based on TerraJ. Thus, the terms and conditions of the * GNU General Public License cover the whole combination. * * In addition, as a special exception, the copyright holders of TerraJ * give you permission to combine this program with free software programs * or libraries that are released under the GNU LGPL and with code included * in the standard release of JOGL, Java Getopt and FreeMarker under the BSD * license (or modified versions of such code, with unchanged license) and with * Apache Commons and Log4J libraries under the Apache license (or modified versions * of such code. You may copy and distribute such a system following the terms * of the GNU GPL for TerraJ and the licenses of the other code concerned, * provided that you include the source code of that other code when and as the * GNU GPL requires distribution of source code. * * Note that people who make modified versions of TerraJ are not obligated to grant * this special exception for their modified versions; it is their choice whether * to do so. The GNU General Public License gives permission to release a modified * version without this exception; this exception also makes it possible to release * a modified version which carries forward this exception. */ /* * JarLibraryLoader.java * * Created on 26 April 2006, 09:05 */ package com.alvermont.terraj.fracplanet.io; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.lang.reflect.Field; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * Attempt to load native libraries from Jar files. Some of the code for this * came from: * * http://forum.java.sun.com/thread.jspa?forumID=406&messageID=2102477&threadID=439060 * * I've modified it not to be specific to Windows. It's not a brilliant solution * but there seems to be little better that can be done given the difficulty * of platform independent native library loading. * * @author martin * @version $Id: JarLibraryLoader.java,v 1.9 2006/07/06 07:46:59 martin Exp $ */ public class JarLibraryLoader { /** Our logger object */ private static Log log = LogFactory.getLog(JarLibraryLoader.class); /** Creates a new instance of JarLibraryLoader */ public JarLibraryLoader() { } /** * Get the name of a library file on this system given a base name. * * @param name The base name of the library eg jogl * @return The name of the corresponding library file eg. libjogl.so on * Linux */ private static String getLibraryName(String name) { String platform = System.getProperty("os.name"); String libname = ""; if (platform.startsWith("Windows")) { // no prefix } else if (platform.equalsIgnoreCase("Mac OS")) { libname = "lib"; } else { libname = "lib"; } return libname + name + getLibraryNameSuffix(); } /** * Return the suffix (extension) of a library file on this system * * @return The name of a library file on this system e.g ".so" on Unix or * ".dll" on Windows. */ private static String getLibraryNameSuffix() { String platform = System.getProperty("os.name"); String suffix = ""; if (platform.startsWith("Windows")) { suffix = ".dll"; } else if (platform.equalsIgnoreCase("Mac OS")) { suffix = ".jnlib"; } else { suffix = ".so"; } return suffix; } /** * Adds our extraction path to the system library path. * * @throws NoSuchFieldException if there is a reflection error * @throws IllegalAccessException if there is an access error during reflection */ public static void setupPath() throws NoSuchFieldException, IllegalAccessException { String dir = System.getProperty("user.home"); dir = new File(dir).getPath(); String newLibPath = dir + File.pathSeparator + System.getProperty("java.library.path"); System.setProperty("java.library.path", newLibPath); Field fieldSysPath = ClassLoader.class.getDeclaredField("sys_paths"); fieldSysPath.setAccessible(true); if (fieldSysPath != null) { fieldSysPath.set(System.class.getClassLoader(), null); } log.debug("Lib path: " + newLibPath); } /** * Get the name of a library resource for this platform * * @param name The name of the library * @return The resource name to use to look up the library */ private static String getLibraryResourceName(String name) { String platform = System.getProperty("os.name"); log.debug("Platform is: " + platform); String path = "/lib/natives_"; if (platform.startsWith("Windows")) { path += "win32/" + name + ".dll"; } else if (platform.equalsIgnoreCase("Mac OS")) { path += "macos/lib" + name + ".jnlib"; } else { path += platform.toLowerCase() + "/lib" + name + ".so"; } log.debug("Path is: " + path); return path; } /** * Extracts a file from the jar so it can be found as a library. There * is no way to load a library directly from the jar file. Uses the * users current directory to write the jar file, which might not work, * should probably fall back to the home dir. We can't use createTempFile * for this as we have to preserve the library filename so that dependencies * can be correctly resolved. The extracted file is marked for deletion on * exit. * * @param name The name of the file to be extracted * @throws IOException if there is an error extracting the library. */ public static File extractLibrary(String name) throws IOException { try { // Gets a stream to the library file File temporaryDll = null; InputStream inputStream = JarLibraryLoader.class.getResourceAsStream(getLibraryResourceName(name)); if (inputStream != null) { temporaryDll = new File( System.getProperty("user.home") + File.separator + name + getLibraryNameSuffix()); String dir = System.getProperty("user.home"); temporaryDll = new File(dir, getLibraryName(name)); temporaryDll.deleteOnExit(); FileOutputStream outputStream = new FileOutputStream(temporaryDll); byte[] array = new byte[8192]; for (int i = inputStream.read(array); i != -1; i = inputStream.read(array)) { outputStream.write(array, 0, i); } outputStream.close(); } return temporaryDll; } catch (IOException ioe) { log.error("IOException loading library", ioe); throw ioe; } } /** * Loads a native library. The native library is assumed * to be in a platform specific subdirectory of the lib directory in the jar. * The library is writen to a local temporary directory and (hopefully) * deleted at JVM exit. * * Dll extraction code taken from Gabriele Piero Nizzoli * http://www.nizzoli.net/index.php?itemid=15 * * @param name The base name of the library to be loaded * @throws IOException if there is a problem loading the library */ public static void loadLibrary(String name) throws IOException { try { File libFile = extractLibrary(name); if (libFile != null) { log.debug("Calling System.load on: " + libFile.getPath()); System.load(libFile.getPath()); } } catch (IOException ioe) { log.error("IOException loading library", ioe); throw ioe; } } }