public static String GetStaticDir(IApp app) { if (app == null) { throw new ArgumentNullException("app"); } IStaticApp entity = app as IStaticApp; if (entity == null) { return(getDefaultStaticDir(app)); } String staticDir = entity.GetStaticDir(); if (strUtil.IsNullOrEmpty(staticDir)) { return(getDefaultStaticDir(app)); } return(staticDir); }