comparison java/src/uk/ac/qmul/eecs/ccmi/utils/ResourceFileWriter.java @ 3:9e67171477bc

PHANTOM Omni Heptic device release

+/*  
+ CCmI Editor - A Collaborative Cross-Modal Diagram Editing Tool
+  
+ Copyright (C) 2011  Queen Mary University of London (http://ccmi.eecs.qmul.ac.uk/)
+
+ 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 3 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, see <http://www.gnu.org/licenses/>.
+*/  
+
+package uk.ac.qmul.eecs.ccmi.utils;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+
+/**
+ * This class is used to extract a native library (e.g. .dll file in windows) from within a jar 
+ * to the local file system, in order to allow the virtual machine to load it.
+ *
+ */
+public class ResourceFileWriter {
+	
+	/**
+	 * Creates an instance of the the class linked to a native library file.
+	 * @param resource the URL of the native library file. The URL can be obtained by  
+	 * @see Class#getResource(String), therefore can be called from a class within a jar file
+	 * which needs to access a static library.  
+	 */
+	public ResourceFileWriter(URL resource){
+		this.resource = resource;
+	}
+	
+	public void serResource(URL resource){
+		this.resource = resource;;
+		path = null;
+	}
+
+	/**
+	 * Writes the file in a directory returned by {@link PreferencesService#get(String, String)}} if defined, or 
+	 * the System default temporary directory otherwise. 
+	 * The path to the file can be retrieved by @see {@link #getFilePath()} and then passed as argument 
+	 * to {@link System#load(String)} 
+	 * 
+	 * @param prefix a prefix the temporary native library file will have in the temporary directory  
+	 */
+	public void writeToDisk(String dir,String fileName){
+		if (resource == null) 
+			return;
+		InputStream in = null;
+		FileOutputStream out = null;
+		File file = new File(dir,fileName);
+		if(file.exists()){ //if file already exists. no job needs to be done.
+			path = file.getAbsolutePath();
+			return;
+		}
+		try{
+			in = resource.openStream();
+			out = new FileOutputStream(file);
+			int byteRead;
+			byte[] b = new byte[1024];
+			while((byteRead = in.read(b)) > 0){
+				out.write(b, 0, byteRead);
+			}
+			path = file.getAbsolutePath();
+		}catch(IOException ioe){
+			path = null;
+		}finally{
+			if(in != null) 
+				try{in.close();}catch(IOException ioe){}
+			if(out != null) 
+				try{out.close();}catch(IOException ioe){}	
+		}
+		
+	}
+	
+	/**
+	 * Returns the absolute path of the last written file. If the writing wasn't successfully 
+	 * or no writing took place yet, then {@code null} is returned. 
+	 * @return the path of the last written file or {@code null}
+	 */
+	public String getFilePath(){
+		return path;
+	}
+	
+	private URL resource;
+	private String path;
+}