code: protected byte[] fileToByteArray(File file) throws IOException
     {
        FileInputStream in = null;
  
        try
        {
           if (channel == null || !channel.isOpen())
           {
              in = PrivilegedFileHelper.fileInputStream(file);
              channel = in.getChannel();
           }
  
           ByteBuffer bb = ByteBuffer.allocate((int)channel.size());
           channel.read(bb);
           if (bb.hasArray())
           {
              return bb.array();
           }
           else
           {
              // impossible code in most cases, as we use heap backed buffer
              byte[] tmpb = new byte[bb.capacity()];
              bb.get(tmpb);
              return tmpb;
           }
        }
        finally
        {
           if (in != null)
           {
              in.close();
              if (channel != null)
              {
                 channel.close();
              }
           }
        }
     }
docs: Convert File to byte array. <br>
  WARNING: Potential lack of memory due to call getAsByteArray() on stream data.
  
  @return byte[] bytes array