jsp过滤器实现网站访问计数器

public class CountFilter implements Filter {
private int count;//访问数量

//初始化
@Override
public void init (FilterConfig config) throws ServletException{
//获取初始化数量
String  param = filterConfig.getInitParameter(“count”);
count = Integer.valueOf(param); 
}
@Override
 public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain) throws IOException ,ServletException{

  //访问数据自增
  count++；
  //将ServletRequest转换为HttpServletRequest
  HttpServletRequest req = (HttpServletRequest)request;
  //获取ServletContext   （Application）
   ServletContext context=req.getSession().getServletContext();
  //将来访数量值放入到ServletContext中
  context.setAttribute(“count”,count);
  //向下传递过滤器
  chain.doFilter(request, response);
}

@Override
 public void destory(){
}
}

<filter>
     <filter-name>countfilter</filter>
      <filter-class>com.filter.CountFilter</filter-class>
<!--设置初始化参数      -->
       <init-param>
        <param-name>count</param-name>
        <param-value>5000</param-value>
       </init-param>
<filter>
<filter-mapping>
    <filter-name>countfilter</filter>
    <url-pattern>/index.jsp</url-pattern>
<filter-mapping>