Login Logout and Cookies!

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Another example of using Cookies for session management in Servlet. Here let us see how to login, maintain user session and then logout.

Our application has the following main pages:
1. Login page
2. Logout page
3. My Profile
4. Index page

The only criteria : You should be not able to logout or view my profile when you have not logged in.

Let us see the code, you can take a look at the project structure from my previous post on Your own Cookie!.

index.html file : Simple html page which displays the login, logout and profile links with Welcome.


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<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>

Welcome!

<a href="login.html">Login</a>
<a href="logoutServlet">Logout</a>
<a href="profileServlet">Profile</a>

</body>
</html>


Next is the index_links.html file : It has html code for displaying the links. For code reusability.


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<a href="login.html">Login</a>
<a href="logoutServlet">Logout</a>
<a href="profileServlet">Profile</a>


login.html Displays the login page


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<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>


<form action="loginServlet" method="post">
Name: <input type="text" name="name">
Password : <input type="text" name="password">
<input type="submit" value="Submit">
</form>

</body>
</html>


LoginServlet.java


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package com.cookie.login.logout;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet{
 
 @Override
 public void doPost(HttpServletRequest request, HttpServletResponse response){
  try{
   
   response.setContentType("text/html");  
   String name = request.getParameter("name");
   String password = request.getParameter("password");
   
   PrintWriter pw = response.getWriter();
   request.getRequestDispatcher("index_links.html").include(request, response);
   
   pw.write("<br>");
   
   if(name.equals("abc") && password.equals("abc123")){
    pw.write("Welcome " + name);
    Cookie c = new Cookie("name", name);
    response.addCookie(c);
   }else{
    pw.write("Incorrect name/password");
    request.getRequestDispatcher("login.html").include(request, response);
   }
   
   pw.close();
   
  }catch (ServletException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }

 
}


LogoutServlet.java


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package com.cookie.login.logout;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LogoutServlet extends HttpServlet {

 @Override
 public void doGet(HttpServletRequest request, HttpServletResponse response) {
  try {
   PrintWriter pw = response.getWriter();
   request.getRequestDispatcher("index_links.html").include(request, response);;
   Cookie[] cs = request.getCookies();

   Cookie c;
   if (cs != null && (c = cs[0]) != null) {
    c.setMaxAge(0);
    response.addCookie(c);
    pw.write("You have successfully logged out");
   } else {
    pw.write("Please login to logout!");
   }
   pw.close();
  } catch (IOException e) {
   e.printStackTrace();
  } catch (ServletException e) {
   e.printStackTrace();
  }
 }

}


ProfileServlet.java


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package com.cookie.login.logout;

import java.io.PrintWriter;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ProfileServlet extends HttpServlet {

 @Override
 public void doGet(HttpServletRequest request, HttpServletResponse response) {

  try {

   PrintWriter pw = response.getWriter();

   request.getRequestDispatcher("index_links.html").include(request,
     response);

   Cookie cs[] = request.getCookies();
   pw.write("<h3>My Profile</h3>");
   Cookie c;
   if(cs != null && (c = cs[0]) != null){

   
   String name = c.getValue();
   if (name != null) {

    pw.write("<br>");
    pw.write("Name : " + name);
    pw.write("<p>");
    pw.write("More data which can be pulled from the DB");
   } 
   }else {
    pw.write("Please login to see your profile");
   }
   pw.close();
   
   StringBuffer sb;
   String s;
   s.to

  } catch (Exception e) {
   e.printStackTrace();
  }

 }

}


web.xml


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<web-app>

<servlet>
<servlet-name>loginServlet</servlet-name>
<servlet-class>com.cookie.login.logout.LoginServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>loginServlet</servlet-name>
<url-pattern>/loginServlet</url-pattern>
</servlet-mapping>


<servlet>
<servlet-name>logoutServlet</servlet-name>
<servlet-class>com.cookie.login.logout.LogoutServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>logoutServlet</servlet-name>
<url-pattern>/logoutServlet</url-pattern>
</servlet-mapping>


<servlet>
<servlet-name>profileServlet</servlet-name>
<servlet-class>com.cookie.login.logout.ProfileServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>profileServlet</servlet-name>
<url-pattern>/profileServlet</url-pattern>
</servlet-mapping>
</web-app>



Place the war file in tomcat's webapp directory.

Run tomcat. Visit http://localhost:8080/Cookies/


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