Servlet – Credential Cookies

Last Updated : 25 Feb, 2022

A cookie is a type of data that is kept on the client’s computer. In order to detect recurring users, you must go through three phases.

A collection of cookies is sent to the browser by the server script. Name, age, or identity number, for example.
This information is saved on the local system by the browser for future use.
When the browser submits a request to the webserver the following time, it transmits the cookies information to the server, which the server uses to identify the user.

We’ll use servlet cookies to develop a login and logout example here. The following files were developed for this application.

index.html
link.html
login.html
ServletLogin.java
ServletLogout.java
ServletProfile.java
web.xml

Example

The project structures will look like this.

index.html:

HTML

<!DOCTYPE html>   
<html>   
<head>   
<meta charset="ISO-8859-1">   
<title>GeeksForgeeks Credential Cookies Example</title>   
</head>   
<body>   
    
  <h1>Welcome to GeeksForGeeks</h1>   
  <a href="login.html">Login</a>|   
  <a href="ServletLogout">Logout</a>|   
  <a href="ServletProfile">Profile</a>   
    
</body>   

link.html:

HTML

<a href="login.html">Login</a>   
<a href="ServletLogout">Logout</a>    
<a href="ServletProfile">Profile</a>   
<hr>   

login.html:

HTML

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

ServletLogin.java:

Java

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 ServletLogin 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("geeksforgeeks")){   
            out.print("You are successfully logged in to GFG!");   
            out.print("<br>Welcome, "+name);   
                
            Cookie ck=new Cookie("name",name);   
            response.addCookie(ck);   
        }else{   
            out.print("sorry, username or password is wrong");   
            request.getRequestDispatcher("login.html").include(request, response);   
        }   
        out.close();   
    }     
}

ServletLogout.java:

Java

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 ServletLogout 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!");   
    }   
}

ServletProfile.java:

Java

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 ServletProfile 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 GfG Profile</b>");   
            out.print("<br>Welcome, "+name);   
        }   
        }else{   
            out.print("Login first");   
            request.getRequestDispatcher("login.html").include(request, response);   
        }   
        out.close();   
    }   
}

web.xml:

XML

<web-app>    
  <servlet>   
    <description></description>   
    <display-name>ServletLogin</display-name>   
    <servlet-name>ServletLogin</servlet-name>   
    <servlet-class>ServletLogin</servlet-class>   
  </servlet>   
  <servlet-mapping>   
    <servlet-name>ServletLogin</servlet-name>   
    <url-pattern>/ServletLogin</url-pattern>   
  </servlet-mapping>   
  <servlet>   
    <description></description>   
    <display-name>ServletProfile</display-name>   
    <servlet-name>ServletProfile</servlet-name>   
    <servlet-class>ServletProfile</servlet-class>   
  </servlet>   
  <servlet-mapping>   
    <servlet-name>ServletProfile</servlet-name>   
    <url-pattern>/ServletProfile</url-pattern>   
  </servlet-mapping>   
  <servlet>   
    <description></description>   
    <display-name>ServletLogout</display-name>   
    <servlet-name>ServletLogout</servlet-name>   
    <servlet-class>ServletLogout</servlet-class>   
  </servlet>   
  <servlet-mapping>   
    <servlet-name>ServletLogout</servlet-name>   
    <url-pattern>/ServletLogout</url-pattern>   
  </servlet-mapping>   
</web-app>

Servlet – Credential Cookies

Example

HTML

HTML

HTML

Java

Java

Java

XML

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