To access request parameters in you JSP files, you could do this below
String value = request.getParameter("value_to_acces");
To access multiple values for the same parameter, you could do this below
String [] values = request.getParameterValues("value_to_access");
For JSP best practice, you should not use scriptlets. Scriplets increases the design pattern called spaghetti.
<c:set var="value" value="${param.value_to_access}"/>
<c:set var="values" value="${paramValues.value_to_access}"/>
Hope this helps!