ChecksumGenerator.java

/* 
 * Licensed under the Apache License, Version 2.0 (the "License");
 *
 * You may not use this file except in compliance with the License.
 *
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Contributions from 2013-2017 where performed either by US government 
 * employees, or under US Veterans Health Administration contracts. 
 *
 * US Veterans Health Administration contributions by government employees
 * are work of the U.S. Government and are not subject to copyright
 * protection in the United States. Portions contributed by government 
 * employees are USGovWork (17USC §105). Not subject to copyright. 
 * 
 * Contribution by contractors to the US Veterans Health Administration
 * during this period are contractually contributed under the
 * Apache License, Version 2.0.
 *
 * See: https://www.usa.gov/government-works
 * 
 * Contributions prior to 2013:
 *
 * Copyright (C) International Health Terminology Standards Development Organisation.
 * Licensed under the Apache License, Version 2.0.
 *
 */



package sh.isaac.api.util;

//~--- JDK imports ------------------------------------------------------------

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.InputStream;

import java.nio.file.Files;

import java.security.DigestInputStream;
import java.security.MessageDigest;

//~--- non-JDK imports --------------------------------------------------------

import javafx.concurrent.Task;

//~--- JDK imports ------------------------------------------------------------

import javax.xml.bind.annotation.adapters.HexBinaryAdapter;

//~--- classes ----------------------------------------------------------------

/**
 * The Class ChecksumGenerator.
 */
public class ChecksumGenerator {
   /**
    * Accepts types like "MD5 or SHA1".
    *
    * @param type the type
    * @param data the data
    * @return the string
    */
   public static String calculateChecksum(String type, byte[] data) {
      try {
         final MessageDigest     md  = MessageDigest.getInstance(type);
         final DigestInputStream dis = new DigestInputStream(new ByteArrayInputStream(data), md);

         dis.read(data);
         return getStringValue(md);
      } catch (final Exception e) {
         throw new RuntimeException("Unexpected error: " + e);
      }
   }

   /**
    * Calculate checksum.
    *
    * @param type the type
    * @param data the data
    * @return the task
    */
   public static Task<String> calculateChecksum(String type, File data) {
      final Task<String> checkSumCalculator = new Task<String>() {
         @Override
         protected String call()
                  throws Exception {
            final long fileLength = data.length();

            updateProgress(0, fileLength);

            final MessageDigest md = MessageDigest.getInstance(type);

            try (InputStream is = Files.newInputStream(data.toPath())) {
               final DigestInputStream dis       = new DigestInputStream(is, md);
               final byte[]            buffer    = new byte[8192];
               long                    loopCount = 0;
               int                     read      = 0;

               while (read != -1) {
                  // update every 10 MB
                  if (loopCount % 1280 == 0) {
                     updateProgress((loopCount * 8192l), fileLength);
                     updateMessage("Calculating " + type + " checksum for " + data.getName() + " - " +
                                   (loopCount * 8192l) + " / " + fileLength);
                  }

                  read = dis.read(buffer);
                  loopCount++;
               }

               updateProgress(fileLength, fileLength);
               updateMessage("Done calculating " + type + " checksum for " + data.getName());
               return getStringValue(md);
            }
         }
      };

      return checkSumCalculator;
   }

   //~--- get methods ---------------------------------------------------------

   /**
    * Gets the string value.
    *
    * @param md the md
    * @return the string value
    */
   private static String getStringValue(MessageDigest md) {
      final byte[] digest = md.digest();

      return new HexBinaryAdapter().marshal(digest)
                                   .toLowerCase();
   }
}