Java tutorial
/* * Copyright (c) 2009, Oracle and/or its affiliates. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of Oracle or the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ // add javaws.jar to the classpath during compilation import javax.jnlp.FileOpenService; import javax.jnlp.FileSaveService; import javax.jnlp.FileContents; import javax.jnlp.ServiceManager; import javax.jnlp.UnavailableServiceException; import java.io.*; public class FileHandler { static private FileOpenService fos = null; static private FileSaveService fss = null; static private FileContents fc = null; // retrieves a reference to the JNLP services private static synchronized void initialize() { if (fss != null) { return; } try { fos = (FileOpenService) ServiceManager.lookup("javax.jnlp.FileOpenService"); fss = (FileSaveService) ServiceManager.lookup("javax.jnlp.FileSaveService"); } catch (UnavailableServiceException e) { fos = null; fss = null; } } // displays open file dialog and reads selected file using FileOpenService public static String open() { initialize(); try { fc = fos.openFileDialog(null, null); return readFromFile(fc); } catch (IOException ioe) { ioe.printStackTrace(System.out); return null; } } // displays saveFileDialog and saves file using FileSaveService public static void save(String txt) { initialize(); try { // Show save dialog if no name is already given if (fc == null) { fc = fss.saveFileDialog(null, null, new ByteArrayInputStream(txt.getBytes()), null); // file saved, done return; } // use this only when filename is known if (fc != null) { writeToFile(txt, fc); } } catch (IOException ioe) { ioe.printStackTrace(System.out); } } // displays saveAsFileDialog and saves file using FileSaveService public static void saveAs(String txt) { initialize(); try { if (fc == null) { // If not already saved. Save-as is like save save(txt); } else { fc = fss.saveAsFileDialog(null, null, fc); save(txt); } } catch (IOException ioe) { ioe.printStackTrace(System.out); } } private static void writeToFile(String txt, FileContents fc) throws IOException { int sizeNeeded = txt.length() * 2; if (sizeNeeded > fc.getMaxLength()) { fc.setMaxLength(sizeNeeded); } BufferedWriter os = new BufferedWriter(new OutputStreamWriter(fc.getOutputStream(true))); os.write(txt); os.close(); } private static String readFromFile(FileContents fc) throws IOException { if (fc == null) { return null; } BufferedReader br = new BufferedReader(new InputStreamReader(fc.getInputStream())); StringBuffer sb = new StringBuffer((int) fc.getLength()); String line = br.readLine(); while (line != null) { sb.append(line); sb.append("\n"); line = br.readLine(); } br.close(); return sb.toString(); } }