在我们的jfinal配置类当中，配置自定义Handler

public void configHandler(Handlers handler) {
        //handler.add(我们自定义handler的实例)
        handler.add(new XssHandler());
    }

新建XssHandler类，继承com.jfinal.handler.Handler

public class XssHandler extends Handler{


    @Override
    public void handle(String target, HttpServletRequest request, HttpServletResponse response, boolean[] isHandled) {
    	// 这里我们也可以相关请求，通过target判断，因为有的时候不是所有请求都加防止XSS,比如一个富文本编辑器提交的html代码，则不要验证，加一个if即可，这里过滤所有
        request = new XssRequestWrapper(request);
         next.handle(target, request, response, isHandled);
    }

}

新建XssRequestWrapper类，继承javax.servlet.http.HttpServletRequestWrapper

public class XssRequestWrapper extends HttpServletRequestWrapper {

    private HttpServletRequest request;

    public XssRequestWrapper(HttpServletRequest request) {
        super(request);
        this.request = request;
    }

    /**
     * 重写getParameter方法
     */
    @Override
    public String getParameter(String name) {
        String value = super.getParameter(name);
        if (value == null) {
            return null;
        }
        value = format(value);
        return value;
    }

    /**
     * 重写getParameterMap
     */
    @Override
    @SuppressWarnings("unchecked")
    public Map<String, String[]> getParameterMap() {
        HashMap<String, String[]> paramMap = (HashMap<String, String[]>) super.getParameterMap();
        paramMap = (HashMap<String, String[]>) paramMap.clone();

        for (Iterator iterator = paramMap.entrySet().iterator(); iterator.hasNext(); ) {
            Map.Entry<String, String[]> entry = (Map.Entry<String, String[]>) iterator.next();
            String [] values = entry.getValue();
            for (int i = 0; i < values.length; i++) {
                if(values[i] instanceof String){
                    values[i] = format(values[i]);
                }
            }
            entry.setValue(values);
        }
        return paramMap;
    }


    /**
     * 重写getParameterValues
     */
    @Override
    public String[] getParameterValues(String name) {
         String[] values = super.getParameterValues(name);  
         int count = values.length;  
            String[] encodedValues = new String[count];  
            for (int i = 0; i < count; i++) {  
                encodedValues[i] = format(values[i]);  
            }  
        return encodedValues;  
    }

    /**
     * 重写getHeader
     */
    @Override
    public String getHeader(String name) {
        // TODO Auto-generated method stub
        return format(super.getHeader(name));
    }


    public String filter(String message) {
        if (message == null)
            return (null);
        message = format(message);
        return message;
    }


     /**
     *  @desc 统一处理特殊字符的方法，替换掉sql和js的特殊字符
     *  @param name 要替换的字符
     */
    private String format(String name) {
        return xssEncode(name);
    }

    /** 
     * 将容易引起xss & sql漏洞的半角字符直接替换成全角字符 
     *  
     * @param s 
     * @return 
     */  
    private static String xssEncode(String s) {  
        if (s == null || s.isEmpty()) {  
            return s;  
        }else{  
            s = stripXSSAndSql(s);  
        }  
        StringBuilder sb = new StringBuilder(s.length() + 16);  
        for (int i = 0; i < s.length(); i++) {  
            char c = s.charAt(i);  
            switch (c) {  
            case '>':  
                sb.append("＞");// 转义大于号  
                break;  
            case '<':  
                sb.append("＜");// 转义小于号  
                break;  
            case '\'':  
                sb.append("＇");// 转义单引号  
                break;  
            case '\"':  
                sb.append("＂");// 转义双引号  
                break;  
            case '&':  
                sb.append("＆");// 转义&  
                break;  
            case '#':  
                sb.append("＃");// 转义#  
                break;  
            default:  
                sb.append(c);  
                break;  
            }  
        }  
        return sb.toString();  
    }  



    /** 
     *  
     * 防止xss跨脚本攻击（替换，根据实际情况调整） 
     */  
    public static String stripXSSAndSql(String value) {  
        if (value != null) {  
            // NOTE: It's highly recommended to use the ESAPI library and  
            // uncomment the following line to  
            // avoid encoded attacks.  
//             value = ESAPI.encoder().canonicalize(value);  
            // Avoid null characters  
/**         value = value.replaceAll("", "");***/  
            // Avoid anything between script tags  
            Pattern scriptPattern = Pattern.compile("<[\r\n| | ]*script[\r\n| | ]*>(.*?)</[\r\n| | ]*script[\r\n| | ]*>", Pattern.CASE_INSENSITIVE);  
            value = scriptPattern.matcher(value).replaceAll("");  
            // Avoid anything in a src="http://www.yihaomen.com/article/java/..." type of e-xpression  
            scriptPattern = Pattern.compile("src[\r\n| | ]*=[\r\n| | ]*[\\\"|\\\'](.*?)[\\\"|\\\']", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);  
            value = scriptPattern.matcher(value).replaceAll("");  
            // Remove any lonesome </script> tag  
            scriptPattern = Pattern.compile("</[\r\n| | ]*script[\r\n| | ]*>", Pattern.CASE_INSENSITIVE);  
            value = scriptPattern.matcher(value).replaceAll("");  
            // Remove any lonesome <script ...> tag  
            scriptPattern = Pattern.compile("<[\r\n| | ]*script(.*?)>", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);  
            value = scriptPattern.matcher(value).replaceAll("");  
            // Avoid eval(...) expressions  
            scriptPattern = Pattern.compile("eval\\((.*?)\\)", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);  
            value = scriptPattern.matcher(value).replaceAll("");  
            // Avoid e-xpression(...) expressions  
            scriptPattern = Pattern.compile("e-xpression\\((.*?)\\)", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);  
            value = scriptPattern.matcher(value).replaceAll("");  
            // Avoid javascript:... expressions  
            scriptPattern = Pattern.compile("javascript[\r\n| | ]*:[\r\n| | ]*", Pattern.CASE_INSENSITIVE);  
            value = scriptPattern.matcher(value).replaceAll("");  
            // Avoid vbscript:... expressions  
            scriptPattern = Pattern.compile("vbscript[\r\n| | ]*:[\r\n| | ]*", Pattern.CASE_INSENSITIVE);  
            value = scriptPattern.matcher(value).replaceAll("");  
            // Avoid οnlοad= expressions  
            scriptPattern = Pattern.compile("onload(.*?)=", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);  
            value = scriptPattern.matcher(value).replaceAll("");  
        }  
        return value;  
    }  


}

网上也看到一个较简单的

private String cleanXSS(String value) {
        value = value.replaceAll("<", "& lt;").replaceAll(">", "& gt;");
        value = value.replaceAll("\\(", "& #40;").replaceAll("\\)", "& #41;");
        value = value.replaceAll("'", "& #39;");
        value = value.replaceAll("eval\\((.*)\\)", "");
        value = value.replaceAll("[\\\"\\\'][\\s]*javascript:(.*)[\\\"\\\']", "\"\"");
        value = value.replaceAll("script", "");
        return value;
    }