1、创建一个过滤器
public class AFilter implements Filter {
private FilterConfig filterconfig;
@Override
public void destroy() {
System.out.println("死翘翘了");
}
@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
/**
* 从application中得到map
* 从request中获取客户端ip
* 查看map中是否存在这个IP，进行计算
*/
//得到application
ServletContext app=filterconfig.getServletContext();
Map<String ,Integer> map=(Map<String ,Integer>)app.getAttribute("map");
//获取客户端的ip
String ip=request.getRemoteAddr();
//判断
if(map.containsKey(ip)){
int count=map.get(ip);
map.put(ip, count+1);
}else{
map.put(ip, 1);
}
app.setAttribute("map", map);
chain.doFilter(request, response); //至进行统计，放行
}
@Override
public void init(FilterConfig fconfig) throws ServletException {
System.out.println("过滤器畜生");
//创建之后马上执行，用作初始化，服务器启动就会执行，而且指执行一次
this.filterconfig=fconfig;
}
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2、新建一个监听
public class Alisten implements ServletContextListener {
public Alisten() {
}
/**
* 在服务器启动时创建Map,保存到ServletContext
*/
public void contextInitialized(ServletContextEvent sce) {
// 创建map
Map<String, Integer> map = new LinkedHashMap<String, Integer>();
// 得到ServletContext
ServletContext application = sce.getServletContext();
application.setAttribute("map", map);
}
public void contextDestroyed(ServletContextEvent arg0) {
}
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3、写一个jsp页面
<body>
<h1 align="center">显示结果</h1>
<table align="center" width="60%" border="1">
<tr>
<td>ip</td>
<td>访问次数</td>
</tr>
<c:forEach items="${applicationScope.map }" var="entry">
<tr>
<td>${entry.key }</td>
<td>${entry.value }</td>
</tr>
</c:forEach>
</table>
</body>