XSS攻擊，即Cross Site Script，跨指令碼攻擊，往web頁面注入html程式碼或者script程式碼，造成頁面混亂。

HttpServletRequestWrapper 是HttpServletRequest的裝飾器。

大體流程：包裝request->建立過濾器->新增過濾器

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import org.apache.commons.lang.StringUtils;

public
 
 class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
   String method = null;

   public DMTRequest(HttpServletRequest servletRequest) {
      super(servletRequest);
   }

   public String[] getParameterValues(String parameter) {
      String[] values = super.getParameterValues(parameter);
      if
 
(values == null) {
         return null;
      } else {
         int count = values.length;
         String[] encodedValues = new String[count];

         for(int i = 0; i < count; ++i) {
            encodedValues[i] = this.cleanXSS(values[i]);
         }

         return encodedValues;
      }
   }

   public
 
 String getParameter(String parameter) {
      String value = super.getParameter(parameter);
      return value == null?null:this.cleanXSS(value);
   }

   public String getHeader(String name) {
      String value = super.getHeader(name);
      return value == null?null:this.cleanXSS(value);
   }

   private String cleanXSS(String value) {
      if(StringUtils.isEmpty(value)) {
         return "";
      } else {
         value = value.replaceAll("\"", "").replaceAll("\'", "").replaceAll("<", "").replaceAll(">", "");
         value = value.replaceAll("eval\\((.*)\\)", "");
         value = value.replaceAll("[\\\"\\\'][\\s]*javascript:(.*)[\\\"\\\']", "\"\"");
         value = value.replaceAll("script", "");
         return value;
      }
   }
}

public class XssFilter implements Filter {

    FilterConfig filterConfig = null;

    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
    }

    public void destroy() {
        this.filterConfig = null;
    }

    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException, ServletException {
        chain.doFilter(new XssHttpServletRequestWrapper (
                (HttpServletRequest) request), response);
    }
}

在web.xml檔案中將該過濾器放在最前面或者是字元編碼過濾器之後：

    filter>
        <filter-name>xssFilter</filter-name>
        <filter-class>xxx.xxx.filter.XssFilter</filter-class>
        <init-param>
            <param-name>exclude</param-name>
            <param-value>/;/scripts/*;/styles/*;/images/*</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>xssFilter</filter-name>
        <url-pattern>*.html</url-pattern>
        <!-- 直接從客戶端過來的請求以及通過forward過來的請求都要經過該過濾器 -->
        <dispatcher>REQUEST</dispatcher>
        <dispatcher>FORWARD</dispatcher>
    </filter-mapping>