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.

1. index.html
2. link.html
3. login.html
4. LoginServlet.java
5. LogoutServlet.java
6. ProfileServlet.java
7. web.xml

File: index.html

  
  
  
  
Servlet Login Example

Welcome to Login App by Cookie

Login|
Logout|
Profile

File: link.html

Login |  
Logout |  
Profile

File: login.html

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("
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("Welcome to Profile");  
            out.print("
Welcome, "+name);  
        }  
        }else{  
            out.print("Please login first");  
            request.getRequestDispatcher("login.html").include(request, response);  
        }  
        out.close();  
    }  
}

File: web.xml

  
  
    
    
      
    LoginServlet  
    LoginServlet  
    com.codebridge.LoginServlet  
    
    
    LoginServlet  
    /LoginServlet  
    
    
      
    ProfileServlet  
    ProfileServlet  
    com.codebridge.ProfileServlet  
    
    
    ProfileServlet  
    /ProfileServlet  
    
    
      
    LogoutServlet  
    LogoutServlet  
    com.codebridge.LogoutServlet  
    
    
    LogoutServlet  
    /LogoutServlet  
    

Output

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