Online IP statistics

1, Fitter Servlet (Filter)

Please refer to

http://www.donews.net/stevenjiang/archive/2004/05/12/18482.aspx

2, httpsessionattributeListener listener

It is used to listen to Attributes for a session object being applied by add (Attribute of a specific name), and the REPLACE (the value of the named Attribute is reset) and transove (session expires or is forced to delete) . These three events correspond to three listening methods:

Public void attributeadded (httpsessionBindingEvent SE)

Public void attributemoved (httpsessionBindingEvent SE)

Public Void AttributeReplaced (httpsessionBindingEvent SE)

//Counterfitter.java, write the visitor's IP to session

Package edu.cust.Web.counter;

Import javax.servlet. *;

Import javax.servlet.http. *;

Import java.io. *;

Import java.util. *;

Public class counterfitter extends httpservlet imports 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;

IF (session.getattribute ("counter"

== NULL) {

Session.setttribute ("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, read the IP from the session and write to the cache

Package edu.cust.Web.counter;

Import javax.servlet. *;

Import javax.servlet.http. *;

Import java.io. *;

Import java.util. *;

Public class onlinevisitor extends httpservlet imports httpsessionattributeListener {

Private static hashset ip = new hashset ();

Public void attributeadd (httpsessionbindingevent se) {

HttpSession session = se.getations ();

String onlineIP = (string) session.getattribute ("counter"

;

IP.Add (OnlineIP);

}

Public void attributeMoved (httpsessionBindingEvent se) {

HttpSession session = se.getations ();

String onlineIP = (string) session.getattribute ("counter"

;

Ip.Remove (OnlineIP);

}

Public void attributeced (httpsessionBindingEvent se) {

}

Public hashset getip () {

Return THIS.IP;

}

Public int getCount () {

Return ip.size ();

}

}

//test.java, test, you can also use JSP pages

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.getations (TRUE);

Response.setContentType (Content_Type);

PrintWriter out = response.getwriter ();

Date Date = new date ();

Out.println (""

;

Out.println ("