过滤器监听器实操----6.21
实验内容
1.用过滤器或监听器实现：记录用户的IP地址和该用户访问过本站点内哪些资源。
2.用监听器实现：在页面上动态显示当前在线人数。
3.用过滤器或监听器实现：记录某个JSP/Servlet（例如index.jsp）自站点启动以来被访问的次数。
提示：
request.getRequestURI() 该方法用于提取被请求的资源的地址
request.getRemoteAddr() 该方法用于提取请求来自于什么IP地址。
第一题
filter文件：
package ch07;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class IP_find implements Filter
{
private FilterConfig fc=null;
public void init(FilterConfig fc) throws ServletException
{
this.fc=fc;
}
public void doFilter (ServletRequest servletrequest,ServletResponse servletresponse,FilterChain chain) throws IOException,ServletException
{
if (fc==null)
{
return;
}
HttpServletRequest request=(HttpServletRequest)servletrequest;
HttpServletResponse response=(HttpServletResponse)servletresponse;
String fromip=request.getRemoteAddr();
//response.setContentType("text/html;charset=GBK"); IP_filter
PrintWriter out=response.getWriter();
out.print(fromip);
out.print("=============================");
String path = request.getContextPath();
String basePath = "==="+request.getRequestURL() ;
//request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+
out.print(basePath);
out.print("=============================");
//response.sendRedirect("../index.htm");
chain.doFilter(servletrequest,servletresponse);
}
public void destroy()
{
fc=null;
}
}
xml文件：
<filter>
<display-name>IP_find</display-name>
<filter-name>IP_find</filter-name>
<filter-class>ch07.IP_find</filter-class>
</filter>
<filter-mapping>
<filter-name>IP_find</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
jsp文件：
<% out.print("welcome~~~123"); %>
第二题和第三题：
xml文件：
<listener>
<listener-class>ch07.Count_renshu</listener-class>
</listener>
login.jsp文件1：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%= "hello"%>
<a href="Logout.jsp">tuichu</a>
</body>
</html>
Logout.jsp文件：
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<%
session.invalidate();
%>
</body>
</html>
listener文件：
package ch07;
import java.io.PrintWriter;
import javax.servlet.*;
import javax.servlet.http.*;
public class Count_renshu implements HttpSessionListener
{
int num=0;
int count=0;
public void sessionCreated(HttpSessionEvent hse)
{
num++;
count++;
System.out.println("当前在线人数："+num);
System.out.println("站点被访问了："+count+"次");
}
public void sessionDestroyed(HttpSessionEvent hse)
{
num--;
System.out.println("当前在线人数："+num);
}
}
