过滤器实现类FilterNum.java
public class FilterNum extends HttpServlet implements Filter {
private static int num=0;//定义全局变量
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
throws IOException, ServletException {
this.num++;
request.setAttribute("num", String.valueOf(num));
filterChain.doFilter(request, response);
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
}
index.jsp页面
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<table width="300" height="100" border="0" cellpadding="0" cellspacing="0">
<tr align="center" bgcolor="lightblue"><Td>目前在线访问流量是:</Td></tr>
<tr align="center">
<td><%=request.getAttribute("num") %>人访问过</td>
</tr>
</table>
</body>
</html>
web.xml文件配置
<filter>
<filter-name>filterNum</filter-name>
<filter-class>com.cn.zj.Filter.FilterNum</filter-class>
</filter>
<filter-mapping>
<filter-name>filterNum</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>