NativeUtils.java

/*
 * Class NativeUtils is published under the The MIT License:
 *
 * Copyright (c) 2012 Adam Heinrich <adam@adamh.cz>
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package umontreal.ssj.util;
 
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class NativeUtils {

   private NativeUtils() {
   }

   public static void loadLibraryFromJar(String path) throws IOException {
 
      if (!path.startsWith("/")) {
         throw new IllegalArgumentException("The path has to be absolute (start with '/').");
      }
 
      // Obtain filename from path
      String[] parts = path.split("/");
      String filename = (parts.length > 1) ? parts[parts.length - 1] : null;
 
      // Split filename to prefix and suffix (extension)
      String prefix = "";
      String suffix = null;
      if (filename != null) {
         parts = filename.split("\\.", 2);
         prefix = parts[0];
         suffix = (parts.length > 1) ? "." + parts[parts.length - 1] : null; // Thanks, davs! :-)
      }
 
      // Check if the filename is okay
      if (filename == null || prefix.length() < 3) {
         throw new IllegalArgumentException("The filename has to be at least 3 characters long.");
      }
 
      // Prepare temporary file
      File temp = File.createTempFile(prefix, suffix);
      temp.deleteOnExit();
 
      if (!temp.exists()) {
         throw new FileNotFoundException("File " + temp.getAbsolutePath() + " does not exist.");
      }
 
      // Prepare buffer for data copying
      byte[] buffer = new byte[1024];
      int readBytes;
 
      // Open and check input stream
      InputStream is = NativeUtils.class.getResourceAsStream(path);
      if (is == null) {
         throw new FileNotFoundException("File " + path + " was not found inside JAR.");
      }
 
      // Open output stream and copy data between source file in JAR and the temporary
      // file
      OutputStream os = new FileOutputStream(temp);
      try {
         while ((readBytes = is.read(buffer)) != -1) {
            os.write(buffer, 0, readBytes);
         }
      } finally {
         // If read/write fails, close streams safely before throwing an exception
         os.close();
         is.close();
      }
 
      // Finally, load the library
      System.load(temp.getAbsolutePath());
   }
}