//這裡對密碼進行加密，再存到資料庫

String password3=StringEncrypt.Encrypt(password);

//SHA256加密演算法
    public static class StringEncrypt {
        /**
         * 對字串加密,加密演算法使用MD5,SHA-1,SHA-256,預設使用SHA-256
         *
         * @param strSrc
         *            要加密的字串
         * @param encName
         *            加密型別
         * @return
         */
        public static String Encrypt(String strSrc) {
            MessageDigest md = null;
            String strDes = null;
            String encName="SHA-256";
            byte[] bt = strSrc.getBytes();
            try {
                md = MessageDigest.getInstance(encName);
                md.update(bt);
                strDes = bytes2Hex(md.digest()); // to HexString
            } catch (NoSuchAlgorithmException e) {
                return null;
            }
            return strDes;
        }

        public static String bytes2Hex(byte[] bts) {
            String des = "";
            String tmp = null;
            for (int i = 0; i < bts.length; i++) {
                tmp = (Integer.toHexString(bts[i] & 0xFF));
                if (tmp.length() == 1) {
                    des += "0";
                }
                des += tmp;
            }
            return des;
        }
    }