The following example show you how to create a servlet filter using the @WebFilter annotation. By accessing this map we can check if a parameter was passed in servlet request. The request object is an instance of a javax.servlet.http.HttpServletRequest object. getParamaterNames() of the ServletRequest interface  to find all the JSP setProperty and jsp getProperty tag with examples of session tracking, implicit objects, el, jstl, mvc, custom tags, file upload, file download, interview questions etc. Check if parameter exists in servlet request.