Java Web Listener Listener Simple implementation of online statistics

Today, we re-learned the basic Java Web Listener Technology, with Sessionlistener Simple implementation of the Web page statistics online number (there is a bug that when the page is closed when the session does not close still exists, Unless you shut down the server), the code is as follows (the front-end page code is not displayed):

Loginservlet.java:

1 Importjavax.servlet.ServletException;2 ImportJavax.servlet.annotation.WebServlet;3 ImportJavax.servlet.http.HttpServlet;4 Importjavax.servlet.http.HttpServletRequest;5 ImportJavax.servlet.http.HttpServletResponse;6 Importjavax.servlet.http.HttpSession;7 Importjava.io.IOException;8 9@WebServlet (name = "Loginservlet", Urlpatterns = "/login")Ten  Public classLoginservletextendsHttpServlet { One @Override A     protected voidDoPost (HttpServletRequest request, httpservletresponse response)throwsservletexception, IOException { -String Username=request.getparameter ("username"); -HttpSession session=request.getsession (); theSession.setattribute ("username", username); -         //Redirect to index.jsp -Response.sendredirect ("index.jsp"); -     } +  - @Override +     protected voidDoget (HttpServletRequest request, httpservletresponse response)throwsservletexception, IOException { A  at     } -}

Exitservlet.java:

1  Packageservlet;2 3 Importjavax.servlet.ServletException;4 ImportJavax.servlet.annotation.WebServlet;5 ImportJavax.servlet.http.HttpServlet;6 Importjavax.servlet.http.HttpServletRequest;7 ImportJavax.servlet.http.HttpServletResponse;8 Importjavax.servlet.http.HttpSession;9 Importjava.io.IOException;Ten  One@WebServlet (name = "Exitservlet", Urlpatterns = "/exit") A  Public classExitservletextendsHttpServlet { - @Override -     protected voidDoPost (HttpServletRequest request, httpservletresponse response)throwsservletexception, IOException { the     //Remove the LoginName parameter from the session -Response.getwriter (). Write ("2222"); -HttpSession session=request.getsession (); -Session.removeattribute ("username"); +         //Redirect to login.jsp -Response.sendredirect ("login.jsp"); +     } A  at @Override -     protected voidDoget (HttpServletRequest request, httpservletresponse response)throwsservletexception, IOException { - DoPost (request, response); -     } -}

Onlinelistener.java:

1  PackageListener;2 3 ImportBean. User;4 5 Importjavax.servlet.ServletContextEvent;6 ImportJavax.servlet.ServletContextListener;7 ImportJavax.servlet.http.HttpSessionAttributeListener;8 Importjavax.servlet.http.HttpSessionEvent;9 ImportJavax.servlet.http.HttpSessionListener;Ten Importjavax.servlet.http.HttpSessionBindingEvent; One  A @javax. Servlet.annotation.WebListener () -  Public classOnlinelistenerImplementsServletcontextlistener, - Httpsessionlistener, Httpsessionattributelistener { the      PublicOnlinelistener () { -     } - @Override -      Public voidcontextinitialized (Servletcontextevent sce) { +       -     } + @Override A      Public voidcontextdestroyed (Servletcontextevent sce) { at      -     } - @Override -      Public voidsessioncreated (httpsessionevent se) { -System.out.println ("Session created"); -     } in @Override -      Public voidsessiondestroyed (httpsessionevent se) { toSYSTEM.OUT.PRINTLN ("Session destroyed"); +     } -      the @Override *      Public voidattributeadded (httpsessionbindingevent sbe) { $       //add a user to the session scopePanax Notoginseng User.adduser (string.valueof (Sbe.getvalue ())); -System.out.println ("Session increment attribute is" +sbe.getname () + "value:" +Sbe.getvalue ()); the     } + @Override A      Public voidattributeremoved (httpsessionbindingevent sbe) { the      //to remove a user from session sessions + User.removeuser (string.valueof (Sbe.getvalue ())); -System.out.println (Sbe.getvalue () + "property has been removed"); $     } $ @Override -      Public voidattributereplaced (httpsessionbindingevent sbe) { -       //get the old property value theString oldvalue=string.valueof (Sbe.getvalue ()); -         //gets the new property valueWuyiString newvalue=string.valueof (Sbe.getsession (). getattribute (Sbe.getname ())); the         //Remove old properties, add new properties - User.removeuser (oldValue); Wu User.adduser (newvalue); -     } About}

Run the results in two different browsers as shown in:

Project Engineering directory such as:

(Keep learning!) Try to refuel! Encourage yourself)

Java Web Listener Listener Simple implementation of online statistics