private   byte [] getSubArray( byte [] array,  int  offset,  int  length) {
         byte [] subArray =  new   byte [length];
         for  ( int  i=offset; i<length; i++)  {
            subArray[i-offset] = array[i];
        }
         return  subArray;
    }

     private   byte [] getSubArray( byte [] array,  int  offset,  int  length) {
         return  ( new  String(array)).substring(offset, offset+length).getBytes();
    }

     private   byte [] getSubArray(StringBuffer sb,  int  offset,  int  length) {
         return  sb.substring(offset, offset+length).getBytes();
    }