Servlet Login And Logout Example Using Cookies

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A cookie may be a kind of information that's stored at the client side.

In the previous page, we learned tons about cookies e.g. the way to create cookies, the way to delete cookies, the way to get cookies etc.

Here, we are going to make a login and logout example by making use of servlet cookies.

We are creating 3 links: login, logout and profile in this example. User can't attend the profile page until he/she is logged in. If the user is logged out, he has to login again to go to profile.

In this application, we've created the following files.

index.html
link.html
login.html
LoginServlet.java
LogoutServlet.java
ProfileServlet.java
web.xml

File:index.html

<!DOCTYPE html>  
<html>  
<head>  
<meta charset="ISO-8859-1">  
<title>Servlet Login Example</title>  
</head>  
<body>  

<h1>Welcome to Login App by Cookie</h1>  
<a href="login.html">Login</a>'  
<a href="LogoutServlet">Logout</a>'  
<a href="ProfileServlet">Profile</a>   

</body>  
</html>

File: link.html

<a href="login.html">Login</a> '  
<a href="LogoutServlet">Logout</a> '  
<a href="ProfileServlet">Profile</a>  
<hr>

File: login.html

<form action="LoginServlet" method="post">  
Name:<input type="text" name="name"><br>  
Password:<input type="password" name="password"><br>  
<input type="submit" value="login">  
</form>

File:LoginServlet.java

package com.javatpoint;  

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 {  
    protected void doPost(HttpServletRequest request, HttpServletResponse response)  
                           throws ServletException, IOException {  
        response.setContentType("text/html");  
        PrintWriter out=response.getWriter();           

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

        String name=request.getParameter("name");  
        String password=request.getParameter("password");          

        if(password.equals("admin123")){  
            out.print("You are successfully logged in!");  
            out.print("<br>Welcome, "+name);              

            Cookie ck=new Cookie("name",name);  
            response.addCookie(ck);  
        }else{  
            out.print("sorry, username or password error!");  
            request.getRequestDispatcher("login.html").include(request, response);  
        }  
          
        out.close();  
    }  

}

File:LogoutServlet.java

package com.javatpoint;    

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 {  
    protected void doGet(HttpServletRequest request, HttpServletResponse response)  
                        throws ServletException, IOException {  
        response.setContentType("text/html");  
        PrintWriter out=response.getWriter();  
                
        request.getRequestDispatcher("link.html").include(request, response);           

        Cookie ck=new Cookie("name","");  
        ck.setMaxAge(0);  
        response.addCookie(ck);           

        out.print("you are successfully logged out!");  
    }  
}

File:ProfileServlet.java

package com.javatpoint;  

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 ProfileServlet extends HttpServlet {  
    protected void doGet(HttpServletRequest request, HttpServletResponse response)  
                          throws ServletException, IOException {  
        response.setContentType("text/html");  
        PrintWriter out=response.getWriter();         

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

        Cookie ck[]=request.getCookies();  
        if(ck!=null){  
         String name=ck[0].getValue();  
        if(!name.equals("")''name!=null){  
            out.print("<b>Welcome to Profile</b>");  
            out.print("<br>Welcome, "+name);  
        }  
        }else{  
           out.print("Please login first");  
            request.getRequestDispatcher("login.html").include(request, response);  
        }  
        out.close();  
    }  
}

File:web.xml

<?xml version="1.0" encoding="UTF-8"?>  
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   
xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">    

  <servlet>  
    <description></description>  
    <display-name>LoginServlet</display-name>  
    <servlet-name>LoginServlet</servlet-name>  
    <servlet-class>com.javatpoint.LoginServlet</servlet-class>  
  </servlet>  

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

  <servlet>  
    <description></description>  
    <display-name>ProfileServlet</display-name>  
    <servlet-name>ProfileServlet</servlet-name>  
    <servlet-class>com.javatpoint.ProfileServlet</servlet-class>  
  </servlet>  

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

  <servlet>  
    <description></description>  
    <display-name>LogoutServlet</display-name>  
    <servlet-name>LogoutServlet</servlet-name>  
    <servlet-class>com.javatpoint.LogoutServlet</servlet-class>  
  </servlet>  

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

</web-app>

Output

If you click on the profile link again, you need to login first.

Cookies In Servlet Hidden Form Field

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Servlet Login And Logout Example Using Cookies

Contents

File:index.html