shiro中JdbcRealm使用salt的问题

public String register(User user) {
        RandomNumberGenerator gen = new SecureRandomNumberGenerator();
        ByteSource salt = gen.nextBytes();

        String hashedPasswordBase64 = new Sha256Hash(user.getPassword(), salt, 1024).toBase64();

        user.setPassword(hashedPasswordBase64);
        user.setSalt(salt.getBytes());

        try {
            userDAO.create(user);
        } catch (SQLException e) {
            e.printStackTrace();
            //TOOD:log error
        }
        return "redirect:login";
    }

protected AuthenticationInfo doGetAuthenticationInfo(AuthenticationToken token) throws AuthenticationException {

        UsernamePasswordToken upToken = (UsernamePasswordToken) token;
        String username = upToken.getUsername();

        // Null username is invalid
        if (username == null) {
            throw new AccountException("Null usernames are not allowed by this realm.");
        }

        Connection conn = null;
        SimpleAuthenticationInfo info = null;
        try {
            conn = dataSource.getConnection();

            String password = null;
            String salt = null;
            switch (saltStyle) {
            case NO_SALT:
                password = getPasswordForUser(conn, username)[0];
                break;
            case CRYPT:
                // TODO: separate password and hash from getPasswordForUser[0]
                throw new ConfigurationException("Not implemented yet");
                //break;
            case COLUMN:
                String[] queryResults = getPasswordForUser(conn, username);
                password = queryResults[0];
                salt = queryResults[1];
                break;
            case EXTERNAL:
                password = getPasswordForUser(conn, username)[0];
                salt = getSaltForUser(username);
            }

            if (password == null) {
                throw new UnknownAccountException("No account found for user [" + username + "]");
            }

            info = new SimpleAuthenticationInfo(username, password.toCharArray(), getName());
            
            if (salt != null) {
                info.setCredentialsSalt(ByteSource.Util.bytes(salt));
            }

        } catch (SQLException e) {
            final String message = "There was a SQL error while authenticating user [" + username + "]";
            if (log.isErrorEnabled()) {
                log.error(message, e);
            }

            // Rethrow any SQL errors as an authentication exception
            throw new AuthenticationException(message, e);
        } finally {
            JdbcUtils.closeConnection(conn);
        }

        return info;
    }