How to encode HttpServletRequest parameters to given format?

Question

I have to encode the HttpServletRequest parameters to avoid XSS attack.

I am trying to use CharacterEncodingFilter provided by Spring.

I have below entry in web.xml,but it does't seem to work.

<filter>
        <filter-name>encodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>

    <filter-mapping>
        <filter-name>encodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

Already gone through other question asked in SO,but no luck so far.

If i pass string like "><img src=x onerror=prompt(1);> for a field from JSP page,it does not encode it,i can do it by getting individual parameter and then encoding it,but what i need is a single point encoding for whole application. Any clue,where i am wrong? or any better solution.

EDIT:-

XSSFilter code:-

Map params = httpRequest.getParameterMap();
        Iterator i = params.keySet().iterator();
        Map result = new HashMap<String, String>();
        boolean valid = true;
        while (i.hasNext()) {
            String key = (String) i.next();
            String value = ((String[]) params.get(key))[0];
            if (!isValidInput(value)) {
                valid = false;
                result.put(key, "Invalid Input");
                logger.error("Invalid input in url " + httpRequest.getServletPath() + " for key : " + key + " value :" + value);

            }
        }