Java tutorial
/* * This file is part of Arduino. * * Copyright 2014 Arduino LLC (http://www.arduino.cc/) * * Arduino 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 St, Fifth Floor, Boston, MA 02110-1301 USA * * As a special exception, you may use this file as part of a free software * library without restriction. Specifically, if other files instantiate * templates or use macros or inline functions from this file, or you compile * this file and link it with other files to produce an executable, this * file does not by itself cause the resulting executable to be covered by * the GNU General Public License. This exception does not however * invalidate any other reasons why the executable file might be covered by * the GNU General Public License. */ package cc.arduino.utils; import org.apache.commons.compress.utils.IOUtils; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; public class FileHash { /** * Calculate a message digest of a file using the algorithm specified. The * result is a string containing the algorithm name followed by ":" and by the * resulting hash in hex. * * @param file * @param algorithm For example "SHA-256" * @return The algorithm followed by ":" and the hash, for example:<br /> * "SHA-256:ee6796513086080cca078cbb383f543c5e508b647a71c9d6f39b7bca41071883" * @throws IOException * @throws NoSuchAlgorithmException */ public static String hash(File file, String algorithm) throws IOException, NoSuchAlgorithmException { FileInputStream in = null; try { in = new FileInputStream(file); byte buff[] = new byte[10240]; MessageDigest digest = MessageDigest.getInstance(algorithm); while (in.available() > 0) { int read = in.read(buff); digest.update(buff, 0, read); } byte[] hash = digest.digest(); String res = ""; for (byte b : hash) { int c = b & 0xFF; if (c < 0x10) res += "0"; res += Integer.toHexString(c); } return algorithm + ":" + res; } finally { IOUtils.closeQuietly(in); } } }