com.playonlinux.utils.Checksum.java Source code

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Here is the source code for com.playonlinux.utils.Checksum.java

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/*
 * Copyright (C) 2015 PRIS Quentin
 *
 * 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 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 Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

package com.playonlinux.utils;

import org.apache.commons.codec.binary.Hex;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Checksum {
    private static final int BLOCK_SIZE = 2048;

    public static String calculate(File fileToCheck, String algorithm)
            throws NoSuchAlgorithmException, IOException {
        FileInputStream inputStream = new FileInputStream(fileToCheck);
        MessageDigest messageDigest = MessageDigest.getInstance(algorithm);

        return Hex.encodeHexString(getDigest(inputStream, messageDigest));
    }

    private static byte[] getDigest(InputStream inputStream, MessageDigest messageDigest) throws IOException {

        messageDigest.reset();
        byte[] bytes = new byte[BLOCK_SIZE];
        int numBytes;
        while ((numBytes = inputStream.read(bytes)) != -1) {
            messageDigest.update(bytes, 0, numBytes);
        }
        return messageDigest.digest();
    }
}