Hash.java

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package org.openslx.imagemaster.util;

import java.security.MessageDigest;
import java.nio.charset.Charset;
import java.security.NoSuchAlgorithmException;

public class Hash
{
   private static final ThreadLocal<MessageDigest> md5hash = new ThreadLocal<MessageDigest>() {

      @Override
      public MessageDigest initialValue()
      {
         try {
            return MessageDigest.getInstance( "MD5" );
         } catch ( NoSuchAlgorithmException e ) {
            e.printStackTrace();
            System.exit( 1 );
            return null;
         }
      }
   };
   private static final ThreadLocal<MessageDigest> sha256hash = new ThreadLocal<MessageDigest>() {

      @Override
      public MessageDigest initialValue()
      {
         try {
            return MessageDigest.getInstance( "SHA-256" );
         } catch ( NoSuchAlgorithmException e ) {
            e.printStackTrace();
            System.exit( 1 );
            return null;
         }
      }
   };
   private static final char[] HEX_CHARS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
   private static final Charset UTF8 = Charset.forName( "UTF-8" );

   // MD5

   public static String md5( final byte[] bytes )
   {
      return toHexString( md5hash.get().digest( bytes ) );
   }

   public static String md5( final String text )
   {
      return md5( text.getBytes( UTF8 ) );
   }

   // SHA-256

   public static String sha256( final byte[] bytes )
   {
      return toHexString( sha256hash.get().digest( bytes ) );
   }

   public static String sha256( final String text )
   {
      return sha256( text.getBytes( UTF8 ) );
   }

   // Helper

   private static String toHexString( final byte[] bytes )
   {
      final char[] hexChars = new char[ bytes.length * 2 ];
      for ( int j = 0; j < bytes.length; ++j ) {
         final int v = bytes[j] & 0xFF;
         hexChars[j * 2] = HEX_CHARS[v >>> 4];
         hexChars[j * 2 + 1] = HEX_CHARS[v & 0x0F];
      }
      return new String( hexChars );
   }

}