/**

     * @param str

     * @return

     */

    public static String stringToMD5(String str, String encode) {

        try {

            byte[] strTemp = str.getBytes(encode);

            MessageDigest mdTemp = MessageDigest.getInstance("MD5");

            mdTemp.update(strTemp);

            return toHexString(mdTemp.digest());

        } catch (Exception e) {

            logger.error(e.toString(), e);

        }

        return null;

    }

    /**

     * @param md

     * @return

     */

    private static String toHexString(byte[] md) {

        char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',

                'a', 'b', 'c', 'd', 'e', 'f' };

        int j = md.length;

        char str[] = new char[j * 2];

        for (int i = 0; i < j; i++) {

            byte byte0 = md[i];

            str[2 * i] = hexDigits[byte0 >>> 4 & 0xf];

            str[i * 2 + 1] = hexDigits[byte0 & 0xf];

        }

        return new String(str);

    }