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在线IP统计

2004-11-23 23:24 591 查看

1、Fitter Servlet （过滤器）
请参考 http://www.donews.net/stevenjiang/archive/2004/05/12/18482.aspx
2、HttpSessionAttributeListener监听器
它是用来监听一个session对象的Attribut被Add(一个特定名称的Attribute每一次被设置),replace(已有名称的Attribute的值被重设)和remove（session过期或被强行删除）时的事件。这三个事件对应三个监听方法：
  public void attributeAdded(HttpSessionBindingEvent se)
public void attributeRemoved(HttpSessionBindingEvent se)
public void attributeReplaced(HttpSessionBindingEvent se)

//CounterFitter.java，将访问者的IP写入session
package edu.cust.web.counter;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;

public class CounterFitter extends HttpServlet implements Filter {
  private FilterConfig filterConfig;
  public void init(FilterConfig filterConfig) {
this.filterConfig = filterConfig;
  }
  // Process the request/response pair
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) {
HttpServletRequest hr = (HttpServletRequest) request;
HttpSession session = hr.getSession(true);
if (session.getAttribute("counter"

== null) {
   session.setAttribute("counter", hr.getRemoteAddr());
}
try {
   filterChain.doFilter(request, response);
}
catch(ServletException sx) {
   filterConfig.getServletContext().log(sx.getMessage());
}
catch(IOException iox) {
   filterConfig.getServletContext().log(iox.getMessage());
}
  }
  //Clean up resources
  public void destroy() {
  }
}

//OnLineVisitor.java，将IP从session读出来并写到缓存
package edu.cust.web.counter;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;

public class OnLineVisitor extends HttpServlet implements HttpSessionAttributeListener {
  private static HashSet ip = new HashSet ();

  public void attributeAdded(HttpSessionBindingEvent se) {
HttpSession session = se.getSession();
String onLineIp = (String)session.getAttribute("counter"

;
ip.add(onLineIp);
}

public void attributeRemoved(HttpSessionBindingEvent se) {
HttpSession session = se.getSession();
String onLineIp = (String)session.getAttribute("counter"

;
ip.remove(onLineIp);
  }

  public void attributeReplaced(HttpSessionBindingEvent se) {

  }
  public HashSet getIP (){
return this.ip;
  }
  public int getCount() {
return ip.size();
  }
}

//test.java，进行测试，也可以用jsp页面
package edu.cust.web.counter;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import edu.cust.web.counter.OnLineVisitor;

public class GetVisitors extends HttpServlet {
  private static final String CONTENT_TYPE = "text/html; charset=GBK";
  //Initialize global variables
  public void init() throws ServletException {
  }
  //Process the HTTP Get request
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
OnLineVisitor onLine = new OnLineVisitor();
HttpSession session = request.getSession(true);

response.setContentType(CONTENT_TYPE);
PrintWriter out = response.getWriter();
Date date = new Date ();
out.println("<html>"

;
out.println("<head><title>当前在线用户统计</title></head>"

;
out.println("<body bgcolor=/"#ffffff/">"

;
out.println("<table width=100% border=0 cellspacing=0 cellpadding=0>"

;

out.println("<tr>"

;
out.println("<td>当前在线人数："+onLine.getCount()+"</td>"

;
out.println("</tr>"

;

out.println("<tr>"

;
out.print("<td>在线IP：</td>"

;
out.println("</tr>"

;
out.println(""

;
Iterator i = onLine.getIP().iterator();
while (i.hasNext()){
out.print("<tr><td>"+(String)i.next()+"</td></tr>"

;
}
out.println("</tr>"

;
out.println("</table>"

;
out.println("</body></html>"

;
  }

  //Process the HTTP Post request
  public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
  }
  //Clean up resources
  public void destroy() {
  }
}
部署文件web.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
  <filter>
<filter-name>counterfitter</filter-name>
<filter-class>edu.cust.web.counter.CounterFitter</filter-class>
  </filter>
  <filter-mapping>
<filter-name>counterfitter</filter-name>
<url-pattern>/*</url-pattern>
  </filter-mapping>
  <listener>
<listener-class>edu.cust.web.counter.OnLineVisitor</listener-class>
  </listener>
  <servlet>
<servlet-name>test</servlet-name>
<servlet-class>edu.cust.web.counter.test</servlet-class>
  </servlet>
  <servlet-mapping>
<servlet-name>test</servlet-name>
<url-pattern>/test</url-pattern>
  </servlet-mapping>
</web-app>

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标签： import session string resources servlet variables

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