given a user submitted input String, filter out any invalid or restricted html. @param input text (i.e. submitted by a user) than may contain html @r

parse expression with map's key and value @param expression like abc${xxx}de${yyy}fg @param variableMap contains key like xxx and yyy @return

handle some param before call controller

print exception to front-end @param response @param code @return

validate reply code @param ftpClient