fiore@0: /*  
fiore@0:  CCmI Editor - A Collaborative Cross-Modal Diagram Editing Tool
fiore@0:   
fiore@0:  Copyright (C) 2011  Queen Mary University of London (http://ccmi.eecs.qmul.ac.uk/)
fiore@0: 
fiore@0:  This program is free software: you can redistribute it and/or modify
fiore@0:  it under the terms of the GNU General Public License as published by
fiore@0:  the Free Software Foundation, either version 3 of the License, or
fiore@0:  (at your option) any later version.
fiore@0: 
fiore@0:  This program is distributed in the hope that it will be useful,
fiore@0:  but WITHOUT ANY WARRANTY; without even the implied warranty of
fiore@0:  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
fiore@0:  GNU General Public License for more details.
fiore@0: 
fiore@0:  You should have received a copy of the GNU General Public License
fiore@0:  along with this program.  If not, see <http://www.gnu.org/licenses/>.
fiore@0: */  
fiore@0: 
fiore@0: package uk.ac.qmul.eecs.ccmi.utils;
fiore@0: 
fiore@0: import java.io.File;
fiore@0: import java.io.FileOutputStream;
fiore@0: import java.io.IOException;
fiore@0: import java.io.InputStream;
fiore@0: import java.net.URL;
fiore@0: 
fiore@0: /**
fiore@0:  * This class is used to extract a native library (e.g. .dll file in windows) from within a jar 
fiore@0:  * to the local file system, in order to allow the virtual machine to load it.
fiore@0:  *
fiore@0:  */
fiore@0: public class NativeLibFileWriter {
fiore@0: 	
fiore@0: 	/**
fiore@0: 	 * Creates an instance of the the class linked to a native library file.
fiore@0: 	 * @param resource the URL of the native library file. The URL can be obtained by  
fiore@0: 	 * @see Class#getResource(String), therefore can be called from a class within a jar file
fiore@0: 	 * which needs to access a static library.  
fiore@0: 	 */
fiore@0: 	public NativeLibFileWriter(URL resource){
fiore@0: 		this.resource = resource;
fiore@0: 	}
fiore@0: 
fiore@0: 	/**
fiore@0: 	 * Writes the file in a directory returned by {@link PreferencesService#get(String, String)}} if defined, or 
fiore@0: 	 * the System default temporary directory otherwise. 
fiore@0: 	 * The path to the file can be retrieved by @see {@link #getFilePath()} and then passed as argument 
fiore@0: 	 * to {@link System#load(String)} 
fiore@0: 	 * 
fiore@0: 	 * @param prefix a prefix the temporary native library file will have in the temporary directory  
fiore@0: 	 */
fiore@0: 	public void writeToDisk(String fileName){
fiore@0: 		InputStream in = null;
fiore@0: 		FileOutputStream out = null;
fiore@0: 		File lib = new File(PreferencesService.getInstance().get("dir.libs", System.getProperty("java.io.tmpdir")),fileName);
fiore@0: 		if(lib.exists()){ //if dll already exists. no job needs to be done.
fiore@0: 			path = lib.getAbsolutePath();
fiore@0: 			return;
fiore@0: 		}
fiore@0: 		try{
fiore@0: 			in = resource.openStream();
fiore@0: 			out = new FileOutputStream(lib);
fiore@0: 			int byteRead;
fiore@0: 			byte[] b = new byte[1024];
fiore@0: 			while((byteRead = in.read(b)) > 0){
fiore@0: 				out.write(b, 0, byteRead);
fiore@0: 			}
fiore@0: 			path = lib.getAbsolutePath();
fiore@0: 		}catch(IOException ioe){
fiore@0: 			path = null;
fiore@0: 		}finally{
fiore@0: 			if(in != null) 
fiore@0: 				try{in.close();}catch(IOException ioe){}
fiore@0: 			if(out != null) 
fiore@0: 				try{out.close();}catch(IOException ioe){}	
fiore@0: 		}
fiore@0: 		
fiore@0: 	}
fiore@0: 	
fiore@0: 	public String getFilePath(){
fiore@0: 		return path;
fiore@0: 	}
fiore@0: 	
fiore@0: 	private URL resource;
fiore@0: 	private String path;
fiore@0: }