Servlet：处理许多可选参数

编写这样的实用程序

public class MapImageServlet extends HttpServlet {//... constructor and other methods ...protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {    // OPTIonAL PARAMETERS     boarderSize = ParamUtil.getDoublevalue(request,"boarderSize", defaultValue);     boarderThickness = ParamUtil.getDoublevalue(request, "boarderThickness", defaultValue);     boarderColor = ParamUtil.getDoublevalue(request,"boarderColor" , defaultValue);     //... do stuff with the parameters ...}}public class ParamUtil{public static double getDoublevalue(ServletRequest request, String paramName, double defaultValue){     if(request.getParameter(paramName) != null){        return Double.valueOf(request.getParameter(paramName));    } else{        return defaultValue;    }}}