public static String getFixedLenStr(String str, int len, char c, boolean fillleft) {        if (str == null)            str = "";        if (str.getBytes().length > len)            return str.substring(0, len);        else {            int len1 = len - str.getBytes().length;            if (len1 > 0) {                byte[] b = new byte[len1];                for (int i = 0; i < len1; i++)                    b[i] = (byte) c;                if (fillleft)                    str = new String(b) + str;                else                    str += new String(b);            }            return str;        }    }

 public static String convertByteToHexStr(byte src) {        byte[] ret = new byte[2];        ret[0] = (byte) (src >> 4 & 0x0F);        ret[0] = (byte) (ret[0] > 9 ? (ret[0] - 10 + ‘a‘) : (ret[0] + ‘0‘));        ret[1] = (byte) (src & 0x0F);        ret[1] = (byte) (ret[1] > 9 ? (ret[1] - 10 + ‘a‘) : (ret[1] + ‘0‘));        return new String(ret);    }

static public byte convertHexStrToByte(String src) {        byte b1 = ‘0‘, b2 = ‘0‘;        byte[] b = src.getBytes();        src = src.toLowerCase();        if (b.length > 1) {            b2 = b[1];            b1 = b[0];        } else if (b.length > 0)            b2 = b[0];        b1 = (byte) (b1 > ‘9‘ ? b1 - ‘a‘ + 10 : b1 - ‘0‘);        b2 = (byte) (b2 > ‘9‘ ? b2 - ‘a‘ + 10 : b2 - ‘0‘);        return (byte) (b1 << 4 | b2);    }