Filter实现动态更换请求链接（css和swf），黑白功能实现
Filter代码

public void doFilter(ServletRequest req, ServletResponse res,
   FilterChain chain) throws IOException, ServletException {
  HttpServletRequest request = (HttpServletRequest) req;
  HttpServletResponse response = (HttpServletResponse) res;
  ServletContext application = request.getSession().getServletContext();
  Object b = application.getAttribute("whiteblackflag");
  if (b != null) {
   boolean flag = (Boolean) b;
   if (flag) { // 要黑白
    Timestamp startDate = (Timestamp) application
      .getAttribute("startDate");
    Timestamp endDate = (Timestamp) application
      .getAttribute("endDate");
    Timestamp now = new Timestamp(new Date().getTime());
    long startDateNum = startDate.getTime();
    long nowNum = now.getTime();
    // System.out.println("开始时间大小："+startDateNum);
    // System.out.println("现在时间大小："+nowNum);
    if (endDate != null) { // 有结束时间
     long endDateNum = endDate.getTime();
     // System.out.println("结束时间大小："+endDateNum);
     if (nowNum >= startDateNum && nowNum <= endDateNum) {
      String url = request.getServletPath();
      // System.out.println(url);
      if (url.indexOf("color.css") != -1) {
       url = url.replaceAll("color.css", "color_grey.css");
       RequestDispatcher go = request
         .getRequestDispatcher(url);
       go.forward(request, response);
      }
      if (url.indexOf(".swf") != -1) {
       // System.out.println("有swf的:"+url);
       url = url.replaceAll(".swf", "_grey.swf");
       // System.out.println("有swf的变化后:"+url);
       RequestDispatcher go = request
         .getRequestDispatcher(url);
       go.forward(request, response);
      }
     }
    } else { // 无结束时间
    // System.out.println("无结束时间。。");
     if (nowNum >= startDateNum) { // 无结束时间，且现在时间大于开始时间才执行
      String url = request.getServletPath();
      System.out.println(url);
      if (url.indexOf("color.css") != -1) {
       url = url.replaceAll("color.css", "color_grey.css");
       RequestDispatcher go = request
         .getRequestDispatcher(url);
       go.forward(request, response);
      }
      if (url.indexOf(".swf") != -1) {
       // System.out.println("有swf的:"+url);
       url = url.replaceAll(".swf", "_grey.swf");
       // System.out.println("有swf的变化后:"+url);
       RequestDispatcher go = request
         .getRequestDispatcher(url);
       go.forward(request, response);