Servlet Login and Logout Example using Cookies

A cookie is a kind of information that is stored at client side.

In the previous page, we learned a lot about cookie e.g. how to create cookie, how to delete cookie, how to get cookie etc.

Here, we are going to create a login and logout example using servlet cookies.

In this example, we are creating 3 links: login, logout and profile. User can't go to profile page until he/she is logged in. If user is logged out, he need to login again to visit profile.

In this application, we have created 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.trainingtrains;

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.trainingtrains;

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.trainingtrains;

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.trainingtrains.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.trainingtrains.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.trainingtrains.LogoutServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>LogoutServlet</servlet-name>
    <url-pattern>/LogoutServlet</url-pattern>
  </servlet-mapping>
</web-app>

download this example (developed using Eclipse IDE)

Output

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

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Servlet Login and Logout Example using Cookies

Output