in the operation of the user is often to check whether to authenticate, then if you want to verify, there must be a large number of code to constantly determine whether the session exists. This kind of code can actually be written directly in the filter.
Login page: login.jsp
<script type= "Text/javascript" >//Check whether to enter a user name or not to submit function check () {var username = Document.getelement
Byid ("username"). Value; if (username==null| | ""
==username) {alert ("Please enter user name");
return false;
return true; } </script> <body> <center> <form action= "Loginservlet" method= "POST" onsubmit= "R
Eturn check () "> <table> <caption> User Login </caption> <tr>
<td> username </td><td><input type= "text" id= "username" name= "username"/></td> </tr> <tr> <td> Password </td><td><input type= "text" name= "Password"/></td> </tr> <tr> <td align= "right" Colspa N= "2" ><input type= "submit" value= "Login" ></td> </tr> </table> </ Form> </center> </body>
Click the login button to enter Loginservlet to save the information.
Loginservlet.java
Package com.org;
Import java.io.IOException;
Import Java.io.PrintWriter;
Import javax.servlet.ServletException;
Import Javax.servlet.http.HttpServlet;
Import Javax.servlet.http.HttpServletRequest;
Import Javax.servlet.http.HttpServletResponse;
Import javax.servlet.http.HttpSession; public class Loginservlet extends HttpServlet {public void doget (HttpServletRequest request, HttpServletResponse resp
Onse) throws Servletexception, IOException {response.setcontenttype ("TEXT/HTML;CHARSET=GBK");
Request.setcharacterencoding ("GBK");
PrintWriter out = Response.getwriter ();
String username = request.getparameter ("username");
HttpSession session = Request.getsession (); Session.setattribute ("username", username); User login to join in session response.sendredirect ("jsp/success.jsp");
Login successfully jumped into success.jsp//test System.out.println ("Username:" +username);
Out.flush ();
Out.close ();
public void DoPost (HttpServletRequest request, httpservletresponse response) Throws Servletexception, IOException {this.doget (request, response);
}
}
Package com.org;
Import java.io.IOException;
Import Java.io.PrintWriter;
Import java.io.UnsupportedEncodingException;
Import Javax.servlet.Filter;
Import Javax.servlet.FilterChain;
Import Javax.servlet.FilterConfig;
Import javax.servlet.ServletException;
Import Javax.servlet.ServletRequest;
Import Javax.servlet.ServletResponse;
Import Javax.servlet.http.HttpServletRequest;
Import Javax.servlet.http.HttpServletResponse;
Import javax.servlet.http.HttpSession; public class Myfilter implements Filter {public void Destroy () {} public void Dofilter (ServletRequest servletreques T, Servletresponse Servletresponse, Filterchain filterchain) throws IOException, servletexception {HttpServletRe
Quest req = (httpservletrequest) servletrequest;
HttpSession session = Req.getsession ();
String username = (string) session.getattribute ("username"); if (username!= null&&username!= "") {//If there is a session now, the request continues to pass Filterchain.dofilter (ServletRequest, SERVL EtresponSE);
else {//jump to the prompt landing page servletrequest.getrequestdispatcher ("/error.jsp"). Forward (ServletRequest, servletresponse);
} public void init (Filterconfig filterconfig) throws servletexception {}}
To test for a class that will fail its session
Invalidateservlet.java
package com.org;
Import java.io.IOException;
Import Java.io.PrintWriter;
Import javax.servlet.ServletException;
Import Javax.servlet.http.HttpServlet;
Import Javax.servlet.http.HttpServletRequest;
Import Javax.servlet.http.HttpServletResponse;
Import javax.servlet.http.HttpSession; public class Invalidateservlet extends HttpServlet {public void doget (HttpServletRequest request, HttpServletResponse
Response) throws Servletexception, IOException {response.setcontenttype ("TEXT/HTML;CHARSET=GBK");
Request.setcharacterencoding ("GBK");
PrintWriter out = Response.getwriter (); HttpSession session =request.getsession (); Get the Session object Session.invalidate ();
Log off session to invalidate//then jump to login page request.getrequestdispatcher ("/login.jsp"). Forward (request, response);
Out.flush ();
Out.close ();
public void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException { }
}
If you access a different page when you are not logged on, jump to the error.jsp page
<body> <center>
Login Success Page success.jsp
<body> <center> Welcome <%=session.getattribute ("username")%> visit <br> < A href= "Invalidateservlet" > Exit </a> </center> </body>
Also, it's a good idea to have several test pages
Test1.jsp test2.jsp inside a few display content can
Configuring Web.xml to implement interception
<filter> <filter-name>myfilter</filter-name> <filter-class>com.org.myfilter</ filter-class> </filter> <filter-mapping> <filter-name>myfilter</filter-name> < url-pattern>/jsp/*</url-pattern> </filter-mapping> <servlet> <servlet-name> Loginservlet</servlet-name> <servlet-class>com.org.LoginServlet</servlet-class> </servlet > <servlet> <servlet-name>InvalidateServlet</servlet-name> <SERVLET-CLASS>COM.ORG.INV alidateservlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>loginservlet </servlet-name> <url-pattern>/loginServlet</url-pattern> </servlet-mapping> < Servlet-mapping> <servlet-name>InvalidateServlet</servlet-name> <url-pattern>/ invalidateservlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcoMe-file>index.jsp</welcome-file> </welcome-file-list>
Except login.jsp in the Webroot directory the rest of the JSP pages under the JSP folder
You can test with the following methods
logon access without first entering login.jsp http://localhost:8080/filter/jsp/test1.jsp prompts you not to sign in.
Then login to enter a user name, and then access test1.jsp can enter or close the browser to reopen, or can enter
Until you log out of the success.jsp page.
Start building with 50+ products and up to 12 months usage for Elastic Compute Service
1 on 1 presale consultation
24/7 Technical Support 6 Free Tickets per Quarter Faster Response
Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.
A comprehensive suite of global cloud computing services to power your business
Payment Methods We Support
