HttpServletRequestWrapper封装了厂商的Request实现类

public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {

    public XssHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
    }

    @Override
    public String getParameter(String name) {
        String value = super.getParameter(name);
        if (!StrUtil.hasEmpty(value)) {
            //转义，即去除html标签
            value = HtmlUtil.filter(value);
        }
        return value;
    }

    @Override
    public String[] getParameterValues(String name) {
        String[] values = super.getParameterValues(name);
        if (values != null) {
            for (int i = 0; i < values.length; i++) {
                String value = values[i];
                if (!StrUtil.hasEmpty(value)) {
                    value = HtmlUtil.filter(value);
                }
                values[i] = value;
            }
        }
        return values;
    }

    @Override
    public Map<String, String[]> getParameterMap() {
        Map<String, String[]> parameters = super.getParameterMap();
        LinkedHashMap<String, String[]> map = new LinkedHashMap<>();
        if (parameters != null) {
            for (String key : parameters.keySet()) {
                String[] values = parameters.get(key);
                for (int i = 0; i < values.length; i++) {
                    String value = values[i];
                    if (!StrUtil.hasEmpty(value)) {
                        value = HtmlUtil.filter(value);
                    }
                    values[i] = value;
                }
                map.put(key, values);
            }
        }
        return map;
    }

    @Override
    public String getHeader(String name) {
        String value = super.getHeader(name);
        if (!StrUtil.hasEmpty(value)) {
            value = HtmlUtil.filter(value);
        }
        return value;
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        InputStream in = super.getInputStream();
        InputStreamReader reader = new InputStreamReader(in, Charset.forName("UTF-8"));
        BufferedReader buffer = new BufferedReader(reader);
        StringBuffer body = new StringBuffer();
        String line = buffer.readLine();
        while (line != null) {
            body.append(line);
            line = buffer.readLine();
        }
        buffer.close();
        reader.close();
        in.close();
        //json转换为map对象
        Map<String, Object> map = JSONUtil.parseObj(body.toString());
        Map<String, Object> result = new LinkedHashMap<>();
        for (String key : map.keySet()) {
            Object val = map.get(key);
            if (val instanceof String) {
                if (!StrUtil.hasEmpty(val.toString())) {
                    result.put(key, HtmlUtil.filter(val.toString()));
                }
            } else {
                result.put(key, val);
            }
        }
        String json = JSONUtil.toJsonStr(result);
        ByteArrayInputStream bain = new ByteArrayInputStream(json.getBytes());
        return new ServletInputStream() {
            @Override
            public boolean isFinished() {
                return false;
            }

            @Override
            public boolean isReady() {
                return false;
            }

            @Override
            public void setReadListener(ReadListener readListener) {

            }

            @Override
            public int read() throws IOException {
                return bain.read();
            }
        };
    }
}

在filter里调用封装

@WebFilter(urlPatterns = "/*")
public class XssFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        XssHttpServletRequestWrapper wrapper = new XssHttpServletRequestWrapper((HttpServletRequest) servletRequest);
        filterChain.doFilter(wrapper, servletResponse);
    }

    @Override
    public void destroy() {

    }
}