Session management is introduced in servlet & JSP (7), but no specific instance is provided. As the saying goes, listening is real. Therefore, this article describes an instance of session management. First, create a web project, logintest. The creation process is the same as that of mydemo. I will not go into details ~ The main function of logintest is: at the beginning, this program uses cookie-based sessions more frequently. When the client disables cookies, the URL rewriting mechanism is used for session tracking.
First, compile an outputsessioninfo tool class. It has a static method that outputs session-related information in the form of tables, so that we can view the information at any time. The Code is as follows:
Package COM. shan. util; import Java. io. *; import javax. servlet. *; import javax. servlet. HTTP. *; import Java. util. *; public class outputsessioninfo {public static void printsessioninfo (printwriter out, httpsession session) {out. println ("<Table>"); out. println ("<tr>"); out. println ("<TD> session Status: </TD>"); If (Session. isnew () {out. println ("<TD> new session </TD>");} else {out. println ("<TD> old session </TD>");} Out. println ("</tr>"); out. println ("<tr>"); out. println ("<TD> session ID: </TD>"); out. println ("<TD>" + session. GETID () + "</TD>"); out. println ("</tr>"); out. println ("<tr>"); out. println ("<TD> session ID: </TD>"); out. println ("<TD>" + session. GETID () + "</TD>"); out. println ("</tr>"); out. println ("<tr>"); out. println ("<TD> Creation Time: </TD>"); out. println ("<TD>" + new date (Session. getcreationtime () + "</TD>"); out. println ("</tr>"); out. println ("<tr>"); out. println ("<TD> last access time: </TD>"); out. println ("<TD>" + new date (Session. getlastaccessedtime () + "</TD>"); out. println ("</tr>"); out. println ("<tr>"); out. println ("<TD> maximum inactivity interval (s): </TD>"); out. println ("<TD>" + session. getmaxinactiveinterval () + "</TD>"); out. println ("</tr>"); out. println ("</table> ");}}
Then, write the loginservlet class. The Code is as follows:
Package COM. shan. web; import Java. io. *; import javax. servlet. *; import javax. servlet. HTTP. *; import COM. shan. util. outputsessioninfo; public class loginservlet extends httpservlet {public void doget (httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {response. setcontenttype ("text/html; charset = UTF-8"); printwriter out = response. getwriter (); httpsession session = request. getsession (); string user = (string) session. getattribute ("user"); out. println ("<HTML>"); // tell the browser not to cache this page out. println ("<meta http-equiv = \" Pragma \ "content = \" no-Cache \ ">"); out. println ("
Compile the loginchkservlet class with the following code:
package com.shan.web;import java.io.*;import javax.servlet.*;import javax.servlet.http.*;public class LoginchkServlet extends HttpServlet{public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException,ServletException {request.setCharacterEncoding("UTF-8");response.setContentType("text/html; charset=UTF-8");String username = request.getParameter("user");String passwd = request.getParameter("passwd");if(username == null || passwd == null || username.equals("") || passwd.equals("")) {response.sendRedirect("login.do");} else {HttpSession session = request.getSession();session.setAttribute("user",username);response.sendRedirect("welcome.do");}}public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {doGet(request,response);}}
Compile the weclomeservlet class with the following code:
Package COM. shan. web; import Java. io. *; import javax. servlet. *; import javax. servlet. HTTP. *; import COM. shan. util. outputsessioninfo; public class welcomeservlet extends httpservlet {public void doget (httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {response. setcontenttype ("text/html; charset = UTF-8"); printwriter out = response. getwriter (); httpsession session = request. getsession (); string user = (string) session. getattribute ("user"); If (user = NULL) {response. sendredirect ("/login. do ");} else {string username = request. getparameter ("username"); string welcomeinfo = "hello," + username; out. println ("<HTML>
Compile the logoutservlet class with the following code:
Package COM. shan. web; import Java. io. *; import javax. servlet. *; import javax. servlet. HTTP. *; public class logoutservlet extends httpservlet {public void doget (httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {response. setcontenttype ("text/html; charset = UTF-8"); printwriter out = response. getwriter (); httpsession session = request. getsession (); Session. invalidate (); out. println ("<HTML>
Finally, configure the Web. xml file. As follows:
<?xml version='1.0' encoding='utf-8'?><web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0" metadata-complete="true"><servlet><servlet-name>LoginServlet</servlet-name><servlet-class>com.shan.web.LoginServlet</servlet-class></servlet><servlet><servlet-name>LoginchkServlet</servlet-name><servlet-class>com.shan.web.LoginchkServlet</servlet-class></servlet><servlet><servlet-name>WelcomeServlet</servlet-name><servlet-class>com.shan.web.WelcomeServlet</servlet-class></servlet><servlet><servlet-name>LogoutServlet</servlet-name><servlet-class>com.shan.web.LogoutServlet</servlet-class></servlet><servlet-mapping><servlet-name>LoginServlet</servlet-name><url-pattern>/login.do</url-pattern></servlet-mapping><servlet-mapping><servlet-name>LoginchkServlet</servlet-name><url-pattern>/loginchk.do</url-pattern></servlet-mapping><servlet-mapping><servlet-name>WelcomeServlet</servlet-name><url-pattern>/welcome.do</url-pattern></servlet-mapping><servlet-mapping><servlet-name>LogoutServlet</servlet-name><url-pattern>/logout.do</url-pattern></servlet-mapping><session-config><session-timeout>5</session-timeout></session-config></web-app>
After compilation, you also need to compile the Java file. Switch to the project directory in the DOS environment and execute the following statement:
javac -classpath D:\apache-tomcat-7.0.33\lib\servlet-api.jar;classes -d classes src\com\shan\util\OutputSessionInfo.java
javac -classpath D:\apache-tomcat-7.0.33\lib\servlet-api.jar;classes -d classes src\\com\shan\web\LoginServlet.java
javac -classpath D:\apache-tomcat-7.0.33\lib\servlet-api.jar;classes -d classes src\\com\shan\web\LoginchkServlet.java
javac -classpath D:\apache-tomcat-7.0.33\lib\servlet-api.jar;classes -d classes src\\com\shan\web\WelcomeServlet.java
javac -classpath D:\apache-tomcat-7.0.33\lib\servlet-api.jar;classes -d classes src\\com\shan\web\LogoutServlet.java
Finally, copy the compiled file to the D: \ apache-Tomcat-7.0.33 \ webapps \ logintest \ WEB-INF \ Classes folder, and put the web. copy XML to the D: \ apache-Tomcat-7.0.33 \ webapps \ logintest \ WEB-INF folder. Execute startup in the DOS environment to start Tomcat. Run result 1.
Figure 1 instance running result
You can disable cookies. in IE or chrome settings, select disable cookies. Then we can see that the cookie-based session tracing mechanism is invalid. In this case, you can use the methods described in servlet & JSP (7) to solve the above problems. I will not elaborate on it here. If you are interested, you can add it yourself to see the effect.
Reprinted please indicate the source: http://blog.csdn.net/iAm333
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